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KSH(1)                           User commands                          KSH(1)

       ksh - Public domain Korn shell

       ksh [+-abCefhikmnprsuvxX] [+-o option] [ [ -c command-string [command-
       name] | -s | file ] [argument ...] ]

       ksh is a command interpreter that is intended for both interactive  and
       shell  script  use.   Its  command  language is a superset of the sh(1)
       shell language.

   Shell Startup
       The following options can be specified only on the command line:

       -c command-string
              the shell executes the command(s) contained in command-string

       -i     interactive mode -- see below

       -l     login shell -- see below interactive mode -- see below

       -s     the shell reads commands from  standard  input;  all  non-option
              arguments are positional parameters

       -r     restricted mode -- see below

       In  addition  to  the  above, the options described in the set built-in
       command can also be used on the command line.

       If neither the -c nor the -s options  are  specified,  the  first  non-
       option  argument  specifies the name of a file the shell reads commands
       from; if there are no non-option arguments, the  shell  reads  commands
       from  standard input.  The name of the shell (i.e., the contents of the
       $0) parameter is determined as follows: if the -c option  is  used  and
       there is a non-option argument, it is used as the name; if commands are
       being read from a file, the file is used as  the  name;  otherwise  the
       name the shell was called with (i.e., argv[0]) is used.

       A  shell  is  interactive  if the -i option is used or if both standard
       input and standard error are attached to a tty.  An  interactive  shell
       has  job control enabled (if available), ignores the INT, QUIT and TERM
       signals, and prints prompts before  reading  input  (see  PS1  and  PS2
       parameters).   For non-interactive shells, the trackall option is on by
       default (see set command below).

       A shell is restricted if the  -r  option  is  used  or  if  either  the
       basename  of  the name the shell is invoked with or the SHELL parameter
       match the pattern *r*sh (e.g., rsh, rksh, rpdksh, etc.).  The following
       restrictions come into effect after the shell processes any profile and
       $ENV files:
         o    the cd command is disabled
         o    the SHELL, ENV and PATH parameters can't be changed
         o    command names can't be specified with absolute or relative paths
         o    the -p option of the command built-in can't be used
         o    redirections that create files can't be used (i.e., >,  >|,  >>,

       A  shell  is privileged if the -p option is used or if the real user-id
       or group-id does not match  the  effective  user-id  or  group-id  (see
       getuid(2),   getgid(2)).    A   privileged   shell   does  not  process
       $HOME/.profile nor the ENV parameter  (see  below),  instead  the  file
       /etc/suid_profile  is processed.  Clearing the privileged option causes
       the shell to set its effective user-id (group-id) to its  real  user-id

       If  the  basename  of the name the shell is called with (i.e., argv[0])
       starts with - or if the -l option is used, the shell is assumed to be a
       login   shell  and  the  shell  reads  and  executes  the  contents  of
       /etc/profile, $HOME/.profile and $ENV if they exist and are readable.

       If the ENV parameter is set when the shell starts (or, in the  case  of
       login shells, after any profiles are processed), its value is subjected
       to parameter,  command,  arithmetic  and  tilde  substitution  and  the
       resulting  file (if any) is read and executed.  If the ENV parameter is
       not set (and not null) the file $HOME/.kshrc  is  included  (after  the
       above mentioned substitutions have been performed).

       The  exit  status  of the shell is 127 if the command file specified on
       the command line could not be opened, or non-zero  if  a  fatal  syntax
       error  occurred  during  the  execution of a script.  In the absence of
       fatal errors, the exit status is that of the last command executed,  or
       zero, if no command is executed.

   Command Syntax
       The  shell  begins parsing its input by breaking it into words.  Words,
       which are sequences of characters, are  delimited  by  unquoted  white-
       space  characters (space, tab and newline) or meta-characters (<, >, |,
       ;, &, ( and )).  Aside from  delimiting  words,  spaces  and  tabs  are
       ignored,  while newlines usually delimit commands.  The meta-characters
       are used in building the following tokens: <, <&, <<, >, >&,  >>,  etc.
       are  used to specify redirections (see Input/Output Redirection below);
       | is used to create pipelines; |& is used to create  co-processes  (see
       Co-Processes  below);  ;  is  used  to  separate commands; & is used to
       create  asynchronous  pipelines;  &&  and  ||  are  used   to   specify
       conditional execution; ;; is used in case statements; (( .. )) are used
       in arithmetic expressions; and lastly,  (  ..  )  are  used  to  create

       White-space  and  meta-characters  can  be  quoted  individually  using
       backslash (\), or in groups using double  (")  or  single  (')  quotes.
       Note  that  the  following characters are also treated specially by the
       shell and must be quoted if they are to represent themselves: \, ",  ',
       #,  $,  `, ~, {, }, *, ? and [.  The first three of these are the above
       mentioned quoting characters (see Quoting below); #,  if  used  at  the
       beginning  of a word, introduces a comment -- everything after the # up
       to the nearest newline is ignored; $ is used  to  introduce  parameter,
       command  and  arithmetic  substitutions  (see  Substitution  below);  `
       introduces an old-style command substitution (see Substitution  below);
       ~  begins  a  directory  expansion (see Tilde Expansion below); { and }
       delimit csh(1) style alternations (see  Brace  Expansion  below);  and,
       finally,  *,  ?  and  [ are used in file name generation (see File Name
       Patterns below).

       As words and tokens are parsed, the shell  builds  commands,  of  which
       there are two basic types: simple-commands, typically programs that are
       executed,  and  compound-commands,  such  as  for  and  if  statements,
       grouping constructs and function definitions.

       A  simple-command consists of some combination of parameter assignments
       (see Parameters below),  input/output  redirections  (see  Input/Output
       Redirections  below),  and  command words; the only restriction is that
       parameter assignments come  before  any  command  words.   The  command
       words,  if  any,  define  the  command  that  is to be executed and its
       arguments.  The command may be a shell built-in command, a function  or
       an  external  command, i.e., a separate executable file that is located
       using the PATH parameter (see Command Execution below).  Note that  all
       command  constructs have an exit status: for external commands, this is
       related to the status returned by wait(2) (if the command could not  be
       found,  the  exit  status is 127, if it could not be executed, the exit
       status is 126); the exit status of other command  constructs  (built-in
       commands, functions, compound-commands, pipelines, lists, etc.) are all
       well defined and are described where the construct is  described.   The
       exit  status  of  a command consisting only of parameter assignments is
       that of the last command substitution performed  during  the  parameter
       assignment or zero if there were no command substitutions.

       Commands  can  be chained together using the | token to form pipelines,
       in which the standard output of each command but the last is piped (see
       pipe(2))  to  the  standard  input  of the following command.  The exit
       status of a pipeline is that of its last command.  A  pipeline  may  be
       prefixed  by  the  !  reserved word which causes the exit status of the
       pipeline to be logically complemented: if the original status was 0 the
       complemented  status  will  be 1, and if the original status was not 0,
       then the complemented status will be 0.

       Lists of commands can be created by separating pipelines by any of  the
       following  tokens:  &&,  ||,  &,  |&  and  ;.   The  first  two are for
       conditional execution: cmd1 && cmd2 executes  cmd2  only  if  the  exit
       status  of cmd1 is zero; || is the opposite -- cmd2 is executed only if
       the exit status of cmd1 is non-zero.  && and || have  equal  precedence
       which  is  higher  than  that  of  &,  |&  and ;, which also have equal
       precedence.  The & token causes the preceding command  to  be  executed
       asynchronously,  that  is,  the  shell starts the command, but does not
       wait for it to complete (the shell does keep track  of  the  status  of
       asynchronous  commands -- see Job Control below).  When an asynchronous
       command is  started  when  job  control  is  disabled  (i.e.,  in  most
       scripts),  the command is started with signals INT and QUIT ignored and
       with input redirected from /dev/null (however,  redirections  specified
       in the asynchronous command have precedence).  The |& operator starts a
       co-process which is special  kind  of  asynchronous  process  (see  Co-
       Processes  below).   Note  that  a  command  must  follow the && and ||
       operators, while a command need not follow  &,  |&  and  ;.   The  exit
       status  of  a  list  is  that  of  the  last command executed, with the
       exception of asynchronous lists, for which the exit status is 0.

       Compound commands are created using the  following  reserved  words  --
       these  words  are  only recognized if they are unquoted and if they are
       used as the first word of a command (i.e., they can't  be  preceded  by
       parameter assignments or redirections):

                         case   else   function   then    !
                         do     esac   if         time    [[
                         done   fi     in         until   {
                         elif   for    select     while   }
       Note: Some shells (but not this one) execute control structure commands
       in  a  subshell  when  one  or  more  of  their  file  descriptors  are
       redirected,  so  any  environment  changes inside them may fail.  To be
       portable, the exec statement should be used instead  to  redirect  file
       descriptors before the control structure.

       In  the following compound command descriptions, command lists (denoted
       as list) that are followed by reserved words  must  end  with  a  semi-
       colon,  a  newline  or  a  (syntactically  correct) reserved word.  For
              { echo foo; echo bar; }
              { echo foo; echo bar<newline>}
              { { echo foo; echo bar; } }
       are all valid, but
              { echo foo; echo bar }
       is not.

       ( list )
              Execute list in a subshell.  There is no implicit  way  to  pass
              environment changes from a subshell back to its parent.

       { list }
              Compound  construct;  list  is  executed, but not in a subshell.
              Note that { and } are reserved words, not meta-characters.

       case word in [ [(] pattern [| pattern] ... ) list ;; ] ... esac
              The case statement attempts to match word against the  specified
              patterns;  the  list  associated  with  the  first  successfully
              matched pattern is executed.  Patterns used in  case  statements
              are  the  same  as those used for file name patterns except that
              the restrictions regarding . and / are dropped.  Note  that  any
              unquoted space before and after a pattern is stripped; any space
              with a pattern must be quoted.  Both the word and  the  patterns
              are  subject  to parameter, command, and arithmetic substitution
              as well as tilde substitution.  For historical reasons, open and
              close braces may be used instead of in and esac (e.g., case $foo
              { *) echo bar; }).  The exit status of a case statement is  that
              of the executed list; if no list is executed, the exit status is

       for name [ in word ... term ] do list done
              where term is either a newline or a ;.  For  each  word  in  the
              specified  word  list, the parameter name is set to the word and
              list is executed.  If in is not used to specify a word list, the
              positional  parameters ("$1", "$2", etc.) are used instead.  For
              historical reasons, open and close braces may be used instead of
              do  and  done (e.g., for i; { echo $i; }).  The exit status of a
              for statement is the last exit status of list; if list is  never
              executed, the exit status is zero.

       if list then list [elif list then list] ... [else list] fi
              If the exit status of the first list is zero, the second list is
              executed; otherwise the list following  the  elif,  if  any,  is
              executed  with similar consequences.  If all the lists following
              the if and elifs fail (i.e., exit  with  non-zero  status),  the
              list  following  the else is executed.  The exit status of an if
              statement is that of non-conditional list that is  executed;  if
              no non-conditional list is executed, the exit status is zero.

       select name [ in word ... term ] do list done
              where  term  is  either  a newline or a ;.  The select statement
              provides an automatic method of presenting the user with a  menu
              and  selecting  from  it.   An  enumerated list of the specified
              words is printed on standard error, followed by a  prompt  (PS3,
              normally   `#?  ').   A  number  corresponding  to  one  of  the
              enumerated words is then read from standard input, name  is  set
              to  the  selected  word  (or  is  unset  if the selection is not
              valid), REPLY is set to what was read (leading/trailing space is
              stripped), and list is executed.  If a blank line (i.e., zero or
              more IFS characters) is entered, the menu is re-printed  without
              executing  list.   When  list  completes, the enumerated list is
              printed if REPLY is null, the prompt is printed and so on.  This
              process  is continues until an end-of-file is read, an interrupt
              is received or a break statement is executed  inside  the  loop.
              If  in  word  ... is omitted, the positional parameters are used
              (i.e., "$1", "$2", etc.).   For  historical  reasons,  open  and
              close braces may be used instead of do and done (e.g., select i;
              { echo $i; }).  The exit status of a select statement is zero if
              a break statement is used to exit the loop, non-zero otherwise.

       until list do list done
              This  works  like  while,  except that the body is executed only
              while the exit status of the first list is non-zero.

       while list do list done
              A while is a prechecked loop.  Its body is executed as often  as
              the exit status of the first list is zero.  The exit status of a
              while statement is the last exit status of the list in the  body
              of  the  loop;  if  the body is not executed, the exit status is

       function name { list }
              Defines the function name.   See  Functions  below.   Note  that
              redirections specified after a function definition are performed
              whenever  the  function  is  executed,  not  when  the  function
              definition is executed.

       name () command
              Mostly the same as function.  See Functions below.

       time [ -p ] [ pipeline ]
              The  time  reserved  word  is described in the Command Execution

       (( expression ))
              The arithmetic expression expression is evaluated; equivalent to
              let  "expression".   See  Arithmetic  Expressions  and  the  let
              command below.

       [[ expression ]]
              Similar to the test and [ ... ] commands (described later), with
              the following exceptions:
                o    Field   splitting   and  file  name  generation  are  not
                     performed on arguments.
                o    The -a (and) and -o (or) operators are replaced  with  &&
                     and ||, respectively.
                o    Operators (e.g., -f, =, !, etc.) must be unquoted.
                o    The  second  operand of != and = expressions are patterns
                     (e.g., the comparison in
                                        [[ foobar = f*r ]]
                o    There are two additional binary operators: < and >  which
                     return  true  if their first string operand is less than,
                     or   greater   than,   their   second   string   operand,
                o    The  single  argument  form  of  test, which tests if the
                     argument has non-zero length, is  not  valid  -  explicit
                     operators must always be used, e.g., instead of
                                              [ str ]
                                           [[ -n str ]]
                o    Parameter,   command  and  arithmetic  substitutions  are
                     performed  as  expressions   are   evaluated   and   lazy
                     expression   evaluation   is  used  for  the  &&  and  ||
                     operators.  This means that in the statement
                                  [[ -r foo && $(< foo) = b*r ]]
                     the $(< foo) is evaluated if and only  if  the  file  foo
                     exists and is readable.

       Quoting  is used to prevent the shell from treating characters or words
       specially.  There are three methods of quoting:  First,  \  quotes  the
       following  character,  unless it is at the end of a line, in which case
       both the \ and the newline are stripped.  Second, a  single  quote  (')
       quotes  everything  up  to the next single quote (this may span lines).
       Third, a double quote (") quotes all characters, except $, ` and \,  up
       to  the  next unquoted double quote.  $ and ` inside double quotes have
       their  usual  meaning   (i.e.,   parameter,   command   or   arithmetic
       substitution)  except  no field splitting is carried out on the results
       of double-quoted substitutions.  If a \ inside a  double-quoted  string
       is followed by \, $, ` or ", it is replaced by the second character; if
       it is followed by a newline, both the \ and the newline  are  stripped;
       otherwise, both the \ and the character following are unchanged.

       Note:  An  earlier  version  of  ksh(1)  changed  the interpretation of
       sequences of the form "...`...\"...`.."  according to  whether  or  not
       POSIX mode was in effect.  In the current implementation, the backslash
       in \" is seen and removed by the outer "...", so the backslash  is  not
       seen by the inner `...`.

       There  are  two  types  of  aliases: normal command aliases and tracked
       aliases.  Command aliases are normally used as a short hand for a  long
       or  often  used  command.   The  shell  expands  command aliases (i.e.,
       substitutes the alias name for its value) when it reads the first  word
       of  a  command.   An  expanded  alias is re-processed to check for more
       aliases.  If a command alias ends in a space or tab, the following word
       is also checked for alias expansion.  The alias expansion process stops
       when a word that is not an alias is found, when a quoted word is  found
       or when an alias word that is currently being expanded is found.

       The following command aliases are defined automatically by the shell:
              autoload='typeset -fu'
              functions='typeset -f'
              hash='alias -t'
              history='fc -l'
              integer='typeset -i'
              login='exec login'
              nohup='nohup '
              r='fc -e -'
              stop='kill -STOP'
              suspend='kill -STOP $$'
              type='whence -v'

       Tracked aliases allow the shell to remember where it found a particular
       command.  The first time the shell does a path  search  for  a  command
       that  is  marked  as  a  tracked  alias,  it saves the full path of the
       command.  The next time the command is executed, the shell  checks  the
       saved  path  to see that it is still valid, and if so, avoids repeating
       the path search.  Tracked aliases can be listed and created using alias
       -t.   Note  that changing the PATH parameter clears the saved paths for
       all tracked aliases.  If the trackall  option  is  set  (i.e.,  set  -o
       trackall or set -h), the shell tracks all commands.  This option is set
       automatically for non-interactive shells.  For interactive shells, only
       the  following  commands are automatically tracked: cat, cc, chmod, cp,
       date, ed, emacs, grep, ls, mail, make, mv, pr, rm, sed, sh, vi and who.

       The first step the shell takes in  executing  a  simple-command  is  to
       perform  substitutions  on  the  words of the command.  There are three
       kinds of substitution: parameter, command  and  arithmetic.   Parameter
       substitutions,  which are described in detail in the next section, take
       the  form  $name  or  ${...};  command  substitutions  take  the   form
       $(command)  or  `command`;  and  arithmetic substitutions take the form

       If a substitution appears outside of double quotes, the results of  the
       substitution are generally subject to word or field splitting according
       to the current value of the IFS parameter.  The IFS parameter specifies
       a  list  of characters which are used to break a string up into several
       words; any characters from the set space, tab and newline  that  appear
       in  the IFS characters are called IFS white space.  Sequences of one or
       more IFS white space characters, in combination with zero or  one  non-
       IFS white space characters delimit a field.  As a special case, leading
       and trailing IFS white space is stripped (i.e., no leading or  trailing
       empty  field is created by it); leading or trailing non-IFS white space
       does create an empty field.  Example: if IFS is set to `<space>:',  the
       sequence  of  characters  `<space>A<space>:<space><space>B::D' contains
       four fields: `A', `B', `' and `D'.  Note that if the IFS  parameter  is
       set to the null string, no field splitting is done; if the parameter is
       unset, the default value of space, tab and newline is used.

       The results of  substitution  are,  unless  otherwise  specified,  also
       subject  to  brace  expansion and file name expansion (see the relevant
       sections below).

       A command substitution is replaced  by  the  output  generated  by  the
       specified  command,  which  is  run  in  a  subshell.   For  $(command)
       substitutions, normal quoting rules are used when  command  is  parsed,
       however,  for  the  `command` form, a \ followed by any of $, ` or \ is
       stripped (a \ followed by any other  character  is  unchanged).   As  a
       special  case in command substitutions, a command of the form < file is
       interpreted to mean substitute the contents of file ($(< foo)  has  the
       same  effect  as  $(cat  foo),  but  it is carried out more efficiently
       because no process is started).
       NOTE: $(command)  expressions  are  currently  parsed  by  finding  the
       matching  parenthesis,  regardless  of quoting.  This will hopefully be
       fixed soon.

       Arithmetic substitutions are replaced by the  value  of  the  specified
       expression.   For  example, the command echo $((2+3*4)) prints 14.  See
       Arithmetic Expressions for a description of an expression.

       Parameters are shell variables; they can be assigned values  and  their
       values  can  be  accessed  using a parameter substitution.  A parameter
       name is either one of the special single punctuation or digit character
       parameters  described  below,  or  a  letter  followed  by zero or more
       letters or digits (`_' counts as a letter).   The  later  form  can  be
       treated as arrays by appending an array index of the form: [expr] where
       expr is an arithmetic expression.  Array indices are currently  limited
       to  the  range 0 through 1023, inclusive.  Parameter substitutions take
       the form $name, ${name} or ${name[expr]}, where  name  is  a  parameter
       name.   If  substitution  is  performed  on  a  parameter  (or an array
       parameter element) that is not set, a null string is substituted unless
       the  nounset option (set -o nounset or set -u) is set, in which case an
       error occurs.

       Parameters can be assigned values in a  number  of  ways.   First,  the
       shell  implicitly  sets  some parameters like #, PWD, etc.; this is the
       only way the special single  character  parameters  are  set.   Second,
       parameters  are  imported  from  the  shell's  environment  at startup.
       Third, parameters can be assigned  values  on  the  command  line,  for
       example,  `FOO=bar'  sets  the parameter FOO to bar; multiple parameter
       assignments can be given on a single  command  line  and  they  can  be
       followed  by  a  simple-command,  in  which case the assignments are in
       effect only for the duration of the command (such assignments are  also
       exported,  see  below  for  implications  of this).  Note that both the
       parameter name and the = must be unquoted for the shell to recognize  a
       parameter  assignment.   The  fourth way of setting a parameter is with
       the export, readonly and typeset commands; see  their  descriptions  in
       the  Command  Execution  section.   Fifth,  for  and  select  loops set
       parameters as well as the getopts, read and set -A  commands.   Lastly,
       parameters  can  be  assigned  values using assignment operators inside
       arithmetic expressions (see Arithmetic Expressions below) or using  the
       ${name=value} form of parameter substitution (see below).

       Parameters  with  the export attribute (set using the export or typeset
       -x commands, or by parameter assignments followed by  simple  commands)
       are  put  in  the  environment  (see environ(7)) of commands run by the
       shell as name=value pairs.  The order in which parameters appear in the
       environment  of a command is unspecified.  When the shell starts up, it
       extracts  parameters  and  their  values  from  its   environment   and
       automatically sets the export attribute for those parameters.

       Modifiers can be applied to the ${name} form of parameter substitution:

              if  name  is set and not null, it is substituted, otherwise word
              is substituted.

              if name is set and not  null,  word  is  substituted,  otherwise
              nothing is substituted.

              if  name is set and not null, it is substituted, otherwise it is
              assigned word and the resulting value of name is substituted.

              if name is set and not null, it is substituted,  otherwise  word
              is  printed  on  standard error (preceded by name:) and an error
              occurs (normally causing termination of a shell script, function
              or  .-script).  If word is omitted the string `parameter null or
              not set' is used instead.

       In the above modifiers, the  :  can  be  omitted,  in  which  case  the
       conditions  only  depend  on  name being set (as opposed to set and not
       null).  If word is needed, parameter,  command,  arithmetic  and  tilde
       substitution  are  performed  on  it;  if word is not needed, it is not

       The following forms of parameter substitution can also be used:

              The number of positional parameters if name is *, @  or  is  not
              specified, or the length of the string value of parameter name.

       ${#name[*]}, ${#name[@]}
              The number of elements in the array name.

       ${name#pattern}, ${name##pattern}
              If pattern matches the beginning of the value of parameter name,
              the matched text is deleted from the result of substitution.   A
              single  #  results in the shortest match, two #'s results in the
              longest match.

       ${name%pattern}, ${name%%pattern}
              Like ${..#..} substitution, but it deletes from the end  of  the

       The  following  special  parameters are implicitly set by the shell and
       cannot be set directly using assignments:

       !      Process id of  the  last  background  process  started.   If  no
              background  processes  have  been  started, the parameter is not

       #      The number of positional parameters (i.e., $1, $2, etc.).

       $      The process ID of the shell, or the PID of the original shell if
              it is a subshell.

       -      The  concatenation of the current single letter options (see set
              command below for list of options).

       ?      The exit status of the last non-asynchronous  command  executed.
              If  the  last  command  was killed by a signal, $? is set to 128
              plus the signal number.

       0      The name the shell was invoked  with  (i.e.,  argv[0]),  or  the
              command-name  if  it  was  invoked  with  the  -c option and the
              command-name was supplied, or  the  file  argument,  if  it  was
              supplied.  If the posix option is not set, $0 is the name of the
              current function or script.

       1 ... 9
              The first nine positional parameters that were supplied  to  the
              shell,  function or .-script.  Further positional parameters may
              be accessed using ${number}.

       *      All positional parameters (except  parameter  0),  i.e.,  $1  $2
              $3....   If  used  outside  of  double  quotes,  parameters  are
              separate words (which are subjected to word splitting); if  used
              within  double  quotes,  parameters  are  separated by the first
              character of the IFS parameter (or the empty string  if  IFS  is

       @      Same  as  $*,  unless  it is used inside double quotes, in which
              case a separate word is generated for each positional  parameter
              -  if  there  are no positional parameters, no word is generated
              ("$@" can be used to access arguments, verbatim, without  losing
              null arguments or splitting arguments with spaces).

       The following parameters are set and/or used by the shell:

       _ (underscore)
              When  an  external  command  is  executed  by  the  shell,  this
              parameter is set in the environment of the new  process  to  the
              path   of  the  executed  command.   In  interactive  use,  this
              parameter is also set in the parent shell to the  last  word  of
              the  previous  command.   When  MAILPATH messages are evaluated,
              this parameter contains the name of the file that  changed  (see
              MAILPATH parameter below).

       CDPATH Search  path for the cd built-in command.  Works the same way as
              PATH for those directories not beginning with / in cd  commands.
              Note  that  if CDPATH is set and does not contain . nor an empty
              path, the current directory is not searched.

              Set to  the  number  of  columns  on  the  terminal  or  window.
              Currently  set  to the cols value as reported by stty(1) if that
              value is non-zero.  This parameter is used  by  the  interactive
              line  editing  modes, and by select, set -o and kill -l commands
              to format information in columns.

       EDITOR If the VISUAL parameter is not set, this parameter controls  the
              command  line  editing  mode for interactive shells.  See VISUAL
              parameter below for how this works.

       ENV    If this parameter is found to be set after any profile files are
              executed,  the  expanded value is used as a shell start-up file.
              It typically contains function and alias definitions.

       ERRNO  Integer value of the shell's errno  variable  --  indicates  the
              reason the last system call failed.

              Not implemented yet.

              If  set,  this parameter is assumed to contain the shell that is
              to be used to execute commands that execve(2) fails  to  execute
              and which do not start with a `#! shell' sequence.

       FCEDIT The editor used by the fc command (see below).

       FPATH  Like  PATH,  but  used when an undefined function is executed to
              locate the file defining the function.  It is also searched when
              a  command  can't  be found using PATH.  See Functions below for
              more information.

              The name of the file used to store history.  When  assigned  to,
              history  is  loaded  from  the  specified  file.   Also, several
              invocations of the shell running on the same machine will  share
              history if their HISTFILE parameters all point at the same file.
              NOTE:  if  HISTFILE isn't set, no history file is used.  This is
              different   from   the   original   Korn   shell,   which   uses
              $HOME/.sh_history;  in  future,  pdksh  may  also  use a default
              history file.

              The number of commands normally stored for history, default 128.

       HOME   The  default  directory  for  the  cd  command  and  the   value
              substituted for an unqualified ~ (see Tilde Expansion below).

       IFS    Internal  field  separator,  used during substitution and by the
              read command, to split values into distinct arguments;  normally
              set  to  space,  tab  and  newline.   See Substitution above for
              Note: this parameter is not imported from the  environment  when
              the shell is started.

              The  version  of  shell  and  the  date  the version was created
              (readonly).  See also the version commands in Emacs Editing Mode
              and Vi Editing Mode sections, below.

       LINENO The  line  number  of  the  function  or  shell  script  that is
              currently being executed.

       LINES  Set to the number of lines on the terminal or window.

              Not implemented yet.

       MAIL   If set, the user will be informed of the arrival of mail in  the
              named file.  This parameter is ignored if the MAILPATH parameter
              is set.

              How often, in seconds, the shell will  check  for  mail  in  the
              file(s)  specified  by MAIL or MAILPATH.  If 0, the shell checks
              before each prompt.  The default is 600 (10 minutes).

              A list of files to be checked  for  mail.   The  list  is  colon
              separated, and each file may be followed by a ? and a message to
              be printed if new mail  has  arrived.   Command,  parameter  and
              arithmetic substitution is performed on the message, and, during
              substitution, the parameter $_ contains the name  of  the  file.
              The default message is you have mail in $_.

       OLDPWD The   previous   working   directory.    Unset  if  cd  has  not
              successfully changed directories since the shell started, or  if
              the shell doesn't know where it is.

       OPTARG When  using  getopts,  it  contains  the  argument  for a parsed
              option, if it requires one.

       OPTIND The index of the last argument  processed  when  using  getopts.
              Assigning   1  to  this  parameter  causes  getopts  to  process
              arguments from the beginning the next time it is invoked.

       PATH   A colon separated list of directories  that  are  searched  when
              looking  for  commands and .'d files.  An empty string resulting
              from a leading or trailing colon,  or  two  adjacent  colons  is
              treated as a `.', the current directory.

              If  set,  this  parameter causes the posix option to be enabled.
              See POSIX Mode below.

       PPID   The process ID of the shell's parent (readonly).

       PS1    PS1 is the primary prompt for  interactive  shells.   Parameter,
              command  and  arithmetic  substitutions  are performed, and ! is
              replaced with the current command number (see fc command below).
              A literal ! can be put in the prompt by placing !! in PS1.  Note
              that since the command line editors try to figure out  how  long
              the  prompt  is  (so  they  know  how  far  it is to edge of the
              screen), escape codes in the prompt tend to mess things up.  You
              can  tell  the  shell  not  to  count certain sequences (such as
              escape codes) by  prefixing  your  prompt  with  a  non-printing
              character  (such as control-A) followed by a carriage return and
              then  delimiting  the  escape  codes  with   this   non-printing
              character.   If  you  don't  have  any  non-printing characters,
              you're out of luck...  BTW, don't blame me for this  hack;  it's
              in  the  original ksh.  Default is `$ ' for non-root users, `# '
              for root.

       PS2    Secondary prompt string, by default `> ', used when  more  input
              is needed to complete a command.

       PS3    Prompt  used  by select statement when reading a menu selection.
              Default is `#? '.

       PS4    Used to  prefix  commands  that  are  printed  during  execution
              tracing  (see  set  -x  command  below).  Parameter, command and
              arithmetic substitutions are performed  before  it  is  printed.
              Default is `+ '.

       PWD    The  current  working  directory.   Maybe unset or null if shell
              doesn't know where it is.

       RANDOM A  simple  random  number  generator.   Every  time  RANDOM   is
              referenced,  it  is  assigned the next number in a random number
              series.  The point in the series  can  be  set  by  assigning  a
              number to RANDOM (see rand(3)).

       REPLY  Default  parameter  for  the read command if no names are given.
              Also used in select loops to store the value that is  read  from
              standard input.

              The  number  of  seconds  since  the  shell  started  or, if the
              parameter has been assigned an  integer  value,  the  number  of
              seconds since the assignment plus the value that was assigned.

       TMOUT  If  set  to  a  positive  integer  in  an  interactive shell, it
              specifies the maximum number of seconds the shell will wait  for
              input  after  printing the primary prompt (PS1).  If the time is
              exceeded, the shell exits.

       TMPDIR The directory shell temporary files are  created  in.   If  this
              parameter is not set, or does not contain the absolute path of a
              writable directory, temporary files are created in /tmp.

       VISUAL If set, this parameter controls the command  line  editing  mode
              for  interactive  shells.   If  the  last  component of the path
              specified in this parameter contains the  string  vi,  emacs  or
              gmacs,  the  vi,  emacs or gmacs (Gosling emacs) editing mode is
              enabled, respectively.

   Tilde Expansion
       Tilde expansion, which is done in parallel with parameter substitution,
       is done on words starting with an unquoted ~.  The characters following
       the tilde, up to the first /, if any, are assumed to be a  login  name.
       If  the  login  name  is  empty, + or -, the value of the HOME, PWD, or
       OLDPWD parameter is substituted, respectively.  Otherwise, the password
       file  is  searched  for  the  login  name,  and the tilde expression is
       substituted with the user's home directory.  If the login name  is  not
       found  in the password file or if any quoting or parameter substitution
       occurs in the login name, no substitution is performed.

       In parameter assignments (those preceding  a  simple-command  or  those
       occurring  in  the  arguments of alias, export, readonly, and typeset),
       tilde expansion is done after any unquoted colon (:), and  login  names
       are also delimited by colons.

       The  home  directory  of previously expanded login names are cached and
       re-used.  The alias -d command may be used to list, change and  add  to
       this cache (e.g., `alias -d fac=/usr/local/facilities; cd ~fac/bin').

   Brace Expansion (alternation)
       Brace expressions, which take the form
       are  expanded to N words, each of which is the concatenation of prefix,
       stri and suffix (e.g., `a{c,b{X,Y},d}e'  expands  to  four  word:  ace,
       abXe,  abYe,  and ade).  As noted in the example, brace expressions can
       be nested and the resulting words are not  sorted.   Brace  expressions
       must contain an unquoted comma (,) for expansion to occur (i.e., {} and
       {foo}  are  not  expanded).   Brace  expansion  is  carried  out  after
       parameter substitution and before file name generation.

   File Name Patterns
       A  file  name  pattern is a word containing one or more unquoted ? or *
       characters or [..] sequences.  Once brace expansion has been performed,
       the  shell replaces file name patterns with the sorted names of all the
       files that match the pattern (if no  files  match,  the  word  is  left
       unchanged).  The pattern elements have the following meaning:

       ?      matches any single character.

       *      matches any sequence of characters.

       [..]   matches  any  of  the characters inside the brackets.  Ranges of
              characters can be specified by separating two characters by a -,
              e.g.,  [a0-9]  matches  the  letter a or any digit.  In order to
              represent itself, a - must either be quoted or the first or last
              character  in the character list.  Similarly, a ] must be quoted
              or the first character in the list if  it  is  represent  itself
              instead  of  the  end  of the list.  Also, a !  appearing at the
              start of the  list  has  special  meaning  (see  below),  so  to
              represent itself it must be quoted or appear later in the list.

       [!..]  like  [..],  except  it  matches  any  character  not inside the

       *(pattern| ... |pattern)
              matches any string of  characters  that  matches  zero  or  more
              occurrences  of  the  specified  patterns.  Example: the pattern
              *(foo|bar) matches the strings `',  `foo',  `bar',  `foobarfoo',

       +(pattern| ... |pattern)
              matches  any  string  of  characters  that  matches  one or more
              occurrences of the specified  patterns.   Example:  the  pattern
              +(foo|bar) matches the strings `foo', `bar', `foobarfoo', etc..

       ?(pattern| ... |pattern)
              matches  the  empty  string  or a string that matches one of the
              specified  patterns.   Example:  the  pattern  ?(foo|bar)   only
              matches the strings `', `foo' and `bar'.

       @(pattern| ... |pattern)
              matches  a  string  that  matches one of the specified patterns.
              Example: the pattern @(foo|bar) only matches the  strings  `foo'
              and `bar'.

       !(pattern| ... |pattern)
              matches  any  string  that  does  not match one of the specified
              patterns.  Examples: the pattern !(foo|bar) matches all  strings
              except `foo' and `bar'; the pattern !(*) matches no strings; the
              pattern !(?)* matches all strings (think about it).

       Note that pdksh currently never matches . and .., but the original ksh,
       Bourne sh and bash do, so this may have to change (too bad).

       Note  that none of the above pattern elements match either a period (.)
       at the start of a file name or a slash (/), even if they are explicitly
       used  in  a [..] sequence; also, the names . and ..  are never matched,
       even by the pattern .*.

       If the markdirs option is set, any directories that  result  from  file
       name generation are marked with a trailing /.

       The  POSIX  character  classes  (i.e.,  [:class-name:]  inside  a  [..]
       expression) are not yet implemented.

   Input/Output Redirection
       When a command is executed, its standard  input,  standard  output  and
       standard error (file descriptors 0, 1 and 2, respectively) are normally
       inherited from the shell.  Three exceptions to  this  are  commands  in
       pipelines,  for  which  standard input and/or standard output are those
       set up by the pipeline, asynchronous commands created when job  control
       is  disabled,  for  which  standard  input  is initially set to be from
       /dev/null, and commands for which any  of  the  following  redirections
       have been specified:

       > file standard  output is redirected to file.  If file does not exist,
              it is created; if it does exist,  is  a  regular  file  and  the
              noclobber  option is set, an error occurs, otherwise the file is
              truncated.  Note that this means the command cmd  _  foo  _  foo
              will  open foo for reading and then truncate it when it opens it
              for writing, before cmd gets a chance to actually read foo.

       >| file
              same as >, except the file is truncated, even if  the  noclobber
              option is set.

       >> file
              same  as  >,  except  the  file  an existing file is appended to
              instead of being truncated.  Also, the file is opened in  append
              mode, so writes always go to the end of the file (see open(2)).

       < file standard  input  is  redirected  from  file, which is opened for

       <> file
              same as <, except the file is opened for reading and writing.

       << marker
              after  reading  the  command  line  containing  this   kind   of
              redirection  (called  a  here  document), the shell copies lines
              from the command source into  a  temporary  file  until  a  line
              matching marker is read.  When the command is executed, standard
              input is redirected from the temporary file.  If marker contains
              no  quoted  characters,  the  contents of the temporary file are
              processed as if enclosed in double quotes each time the  command
              is  executed, so parameter, command and arithmetic substitutions
              are performed, along with backslash (\) escapes for $, `, \  and
              \newline.   If  multiple  here  documents  are  used on the same
              command line, they are saved in order.

       <<- marker
              same as <<, except leading tabs are stripped from lines  in  the
              here document.

       <& fd  standard input is duplicated from file descriptor fd.  fd can be
              a single digit,  indicating  the  number  of  an  existing  file
              descriptor,   the  letter  p,  indicating  the  file  descriptor
              associated with the output of the  current  co-process,  or  the
              character -, indicating standard input is to be closed.

       >& fd  same as <&, except the operation is done on standard output.

       In  any  of  the  above  redirections,  the  file  descriptor  that  is
       redirected (i.e., standard input or standard output) can be  explicitly
       given  by  preceding  the  redirection with a single digit.  Parameter,
       command and arithmetic substitutions, tilde substitutions and  (if  the
       shell  is  interactive)  file  name generation are all performed on the
       file, marker and fd arguments of redirections.  Note however, that  the
       results  of  any file name generation are only used if a single file is
       matched; if multiple files match, the word  with  the  unexpanded  file
       name  generation  characters  is used.  Note that in restricted shells,
       redirections which can create files cannot be used.

       For simple-commands, redirections may appear anywhere in  the  command,
       for  compound-commands  (if  statements,  etc.),  any redirections must
       appear at the end.  Redirections  are  processed  after  pipelines  are
       created and in the order they are given, so
              cat /foo/bar 2>&1 > /dev/null | cat -n
       will print an error with a line number prepended to it.

   Arithmetic Expressions
       Integer arithmetic expressions can be used with the let command, inside
       $((..)) expressions, inside array  references  (e.g.,  name[expr]),  as
       numeric  arguments  to  the  test  command,  and  as  the  value  of an
       assignment to an integer parameter.

       Expression  may  contain  alpha-numeric  parameter  identifiers,  array
       references,  and  integer  constants  and  may  be  combined  with  the
       following C operators  (listed  and  grouped  in  increasing  order  of

       Unary operators:
              + - ! ~ ++ --

       Binary operators:
              = *= /= %= += -= <<= >>= &= ^= |=
              == !=
              < <= >= >
              << >>
              + -
              * / %

       Ternary operator:
              ?: (precedence is immediately higher than assignment)

       Grouping operators:
              ( )

       Integer  constants  may  be  specified  with  arbitrary bases using the
       notation base#number, where base is a decimal  integer  specifying  the
       base, and number is a number in the specified base.

       The operators are evaluated as follows:

              unary +
                     result is the argument (included for completeness).

              unary -

              !      logical  not;  the  result is 1 if argument is zero, 0 if

              ~      arithmetic (bit-wise) not.

              ++     increment; must be applied to a parameter (not a  literal
                     or other expression) - the parameter is incremented by 1.
                     When used  as  a  prefix  operator,  the  result  is  the
                     incremented  value  of  the  parameter,  when  used  as a
                     postfix operator, the result is the original value of the

              --     similar to ++, except the parameter is decremented by 1.

              ,      separates  two arithmetic expressions; the left hand side
                     is evaluated first, then the right.  The result is  value
                     of the expression on the right hand side.

              =      assignment;  variable  on the left is set to the value on
                     the right.

              *= /= %= += -= <<= >>= &= ^= |=
                     assignment operators; _var_ _op_= _expr_ is the  same  as
                     _var_ = _var_ _op_ ( _expr_ ).

              ||     logical  or;  the  result is 1 if either argument is non-
                     zero, 0 if not.  The right argument is evaluated only  if
                     the left argument is zero.

              &&     logical  and;  the result is 1 if both arguments are non-
                     zero, 0 if not.  The right argument is evaluated only  if
                     the left argument is non-zero.

              |      arithmetic (bit-wise) or.

              ^      arithmetic (bit-wise) exclusive-or.

              &      arithmetic (bit-wise) and.

              ==     equal;  the result is 1 if both arguments are equal, 0 if

              !=     not equal; the result is 0 if both arguments are equal, 1
                     if not.

              <      less  than;  the result is 1 if the left argument is less
                     than the right, 0 if not.

              <= >= >
                     less than or equal, greater than or equal, greater  than.
                     See <.

              << >>  shift  left (right); the result is the left argument with
                     its bits shifted left (right) by the amount given in  the
                     right argument.

              + - * /
                     addition, subtraction, multiplication, and division.

              %      remainder; the result is the remainder of the division of
                     the left argument by the right.  The sign of  the  result
                     is unspecified if either argument is negative.

              _arg1_ ? _arg2_ : _arg3_
                     if  _arg1_  is  non-zero, the result is _arg2_, otherwise

       A co-process, which is a pipeline created with the |& operator,  is  an
       asynchronous  process that the shell can both write to (using print -p)
       and read from (using read -p).  The input and output of the  co-process
       can  also  be manipulated using >&p and <&p redirections, respectively.
       Once a co-process has been started, another can't be started until  the
       co-process  exits,  or  until  the co-process input has been redirected
       using an exec n>&p redirection.  If a co-process's input is  redirected
       in  this  way,  the next co-process to be started will share the output
       with the first co-process, unless the output of the initial  co-process
       has been redirected using an exec n<&p redirection.

       Some notes concerning co-processes:
         o    the  only  way  to close the co-process input (so the co-process
              reads an end-of-file) is to redirect the  input  to  a  numbered
              file  descriptor and then close that file descriptor (e.g., exec
              3>&p;exec 3>&-).
         o    in order for co-processes to share a common  output,  the  shell
              must keep the write portion of the output pipe open.  This means
              that end of file will not be  detected  until  all  co-processes
              sharing  the  co-process output have exited (when they all exit,
              the shell closes its copy of the pipe).  This can be avoided  by
              redirecting  the  output  to a numbered file descriptor (as this
              also causes the shell  to  close  its  copy).   Note  that  this
              behaviour  is  slightly  different  from the original Korn shell
              which closes its copy of the write portion of the  co-processes'
              output  when  the  most  recently started co-process (instead of
              when all sharing co-processes) exits.
         o    print -p will ignore SIGPIPE signals during writes if the signal
              is not being trapped or ignored; the same is not true if the co-
              process input has been duplicated to another file descriptor and
              print -un is used.

       Functions  are  defined using either Korn shell function name syntax or
       the Bourne/POSIX shell name() syntax  (see  below  for  the  difference
       between  the two forms).  Functions are like .-scripts in that they are
       executed in the current environment, however, unlike  .-scripts,  shell
       arguments  (i.e.,  positional  parameters,  $1, etc.) are never visible
       inside them.  When the shell is determining the location of a  command,
       functions  are  searched  after  special  built-in commands, and before
       regular and non-regular built-ins, and before the PATH is searched.

       An existing function may be deleted using unset  -f  function-name.   A
       list  of  functions  can  be obtained using typeset +f and the function
       definitions can be listed using typeset  -f.   autoload  (which  is  an
       alias  for typeset -fu) may be used to create undefined functions; when
       an  undefined  function  is  executed,  the  shell  searches  the  path
       specified  in  the FPATH parameter for a file with the same name as the
       function, which, if found is read and executed.  If after executing the
       file,  the  named  function  is  found  to  be defined, the function is
       executed, otherwise, the normal command search is continued (i.e.,  the
       shell searches the regular built-in command table and PATH).  Note that
       if a command is not found using PATH, an attempt is made to autoload  a
       function  using  FPATH (this is an undocumented feature of the original
       Korn shell).

       Functions can have two attributes, trace and export, which can  be  set
       with typeset -ft and typeset -fx, respectively.  When a traced function
       is executed, the shell's xtrace option is turned on for  the  functions
       duration,  otherwise  the  xtrace  option  is  turned  off.  The export
       attribute of functions is currently not used.   In  the  original  Korn
       shell,  exported  functions  are  visible  to  shell  scripts  that are

       Since  functions  are  executed  in  the  current  shell   environment,
       parameter  assignments  made  inside  functions  are  visible after the
       function completes.  If this is not the  desired  effect,  the  typeset
       command  can  be  used  inside  a function to create a local parameter.
       Note that special parameters (e.g., $$, $!) can't  be  scoped  in  this

       The  exit  status of a function is that of the last command executed in
       the function.  A function can be made to finish immediately  using  the
       return  command;  this  may also be used to explicitly specify the exit

       Functions  defined  with  the  function  reserved  word   are   treated
       differently  in  the  following ways from functions defined with the ()
         o    the $0 parameter is set to the name  of  the  function  (Bourne-
              style functions leave $0 untouched).
         o    parameter  assignments  preceding function calls are not kept in
              the shell environment  (executing  Bourne-style  functions  will
              keep assignments).
         o    OPTIND  is  saved/reset  and restored on entry and exit from the
              function so getopts can be used properly both inside and outside
              the  function (Bourne-style functions leave OPTIND untouched, so
              using getopts inside a function interferes  with  using  getopts
              outside the function).  In the future, the following differences
              will also be added:
         o    A separate trap/signal  environment  will  be  used  during  the
              execution  of functions.  This will mean that traps set inside a
              function will not affect the shell's traps and signals that  are
              not  ignored  in  the shell (but may be trapped) will have their
              default effect in a function.
         o    The EXIT trap, if set in a function, will be executed after  the
              function returns.

   POSIX Mode
       The  shell  is  intended to be POSIX compliant, however, in some cases,
       POSIX behaviour is contrary either to the original Korn shell behaviour
       or  to  user  convenience.   How  the  shell  behaves in these cases is
       determined by the state of the posix option (set -o posix) -- if it  is
       on,  the  POSIX  behaviour is followed, otherwise it is not.  The posix
       option is set automatically when the shell starts up if the environment
       contains  the  POSIXLY_CORRECT  parameter.   (The  shell  can  also  be
       compiled so that it is in  POSIX  mode  by  default,  however  this  is
       usually not desirable).

       The following is a list of things that are affected by the state of the
       posix option:
         o    kill -l output: in posix mode, signal names  are  listed  one  a
              single  line;  in  non-posix  mode,  signal  numbers,  names and
              descriptions are printed in columns.  In future,  a  new  option
              (-v perhaps) will be added to distinguish the two behaviours.
         o    fg exit status: in posix mode, the exit status is 0 if no errors
              occur; in non-posix mode, the exit status is that  of  the  last
              foregrounded job.
         o    eval  exit  status:  if eval gets to see an empty command (e.g.,
              eval "`false`"), its exit status in posix mode will  be  0.   In
              non-posix  mode,  it will be the exit status of the last command
              substitution that was done in the processing of the arguments to
              eval (or 0 if there were no command substitutions).
         o    getopts:  in  posix  mode,  options must start with a -; in non-
              posix mode, options can start with either - or +.
         o    brace expansion (also known  as  alternation):  in  posix  mode,
              brace  expansion is disabled; in non-posix mode, brace expansion
              enabled.  Note that set -o posix (or setting the POSIXLY_CORRECT
              parameter)  automatically  turns  the  braceexpand  option  off,
              however it can be explicitly turned on later.
         o    set -: in posix mode, this does not clear the verbose or  xtrace
              options; in non-posix mode, it does.
         o    set  exit  status: in posix mode, the exit status of set is 0 if
              there are no errors; in non-posix mode, the exit status is  that
              of  any  command  substitutions  performed in generating the set
              command.  For example, `set -- `false`; echo  $?'  prints  0  in
              posix mode, 1 in non-posix mode.  This construct is used in most
              shell scripts that use the old getopt(1) command.
         o    argument expansion  of  alias,  export,  readonly,  and  typeset
              commands: in posix mode, normal argument expansion done; in non-
              posix mode, field splitting, file globing, brace  expansion  and
              (normal)  tilde  expansion  are turned off, and assignment tilde
              expansion is turned on.
         o    signal specification: in posix mode, signals can be specified as
              digits  only  if signal numbers match POSIX values (i.e., HUP=1,
              INT=2, QUIT=3, ABRT=6, KILL=9, ALRM=14, and  TERM=15);  in  non-
              posix mode, signals can be always digits.
         o    alias  expansion: in posix mode, alias expansion is only carried
              out  when  reading  command  words;  in  non-posix  mode,  alias
              expansion  is  carried  out  on any word following an alias that
              ended in a space.  For example, the following for loop
              alias a='for ' i='j'
              a i in 1 2; do echo i=$i j=$j; done
       uses parameter i in posix mode, j in non-posix mode.
         o    test: in posix mode,  the  expression  "-t"  (preceded  by  some
              number  of  "!"  arguments)  is  always true as it is a non-zero
              length string; in non-posix mode, it tests if file descriptor  1
              is  a  tty (i.e., the fd argument to the -t test may be left out
              and defaults to 1).

   Command Execution
       After evaluation of command line arguments, redirections and  parameter
       assignments,  the  type of command is determined: a special built-in, a
       function, a regular built-in or the name of a  file  to  execute  found
       using  the  PATH  parameter.   The  checks are made in the above order.
       Special built-in commands differ from other commands in that  the  PATH
       parameter is not used to find them, an error during their execution can
       cause a non-interactive shell to exit and  parameter  assignments  that
       are  specified before the command are kept after the command completes.
       Just to confuse things, if the posix option  is  turned  off  (see  set
       command  below) some special commands are very special in that no field
       splitting,  file  globing,  brace  expansion  nor  tilde  expansion  is
       performed  on  arguments  that look like assignments.  Regular built-in
       commands are different only in that the PATH parameter is not  used  to
       find them.

       The  original  ksh  and  POSIX  differ  somewhat  in which commands are
       considered special or regular:

       POSIX special commands

              .          continue   exit       return     trap
              :          eval       export     set        unset
              break      exec       readonly   shift

       Additional ksh special commands

              builtin    times      typeset

       Very special commands (non-posix mode)

              alias      readonly   set        typeset

       POSIX regular commands

              alias      command    fg         kill       umask
              bg         false      getopts    read       unalias

              cd         fc         jobs       true       wait

       Additional ksh regular commands

              [          let        pwd        ulimit
              echo       print      test       whence

       In the future, the additional ksh special and regular commands  may  be
       treated differently from the POSIX special and regular commands.

       Once  the  type  of  the  command has been determined, any command line
       parameter assignments are performed and exported for  the  duration  of
       the command.

       The following describes the special and regular built-in commands:

       . file [arg1 ...]
              Execute  the  commands  in file in the current environment.  The
              file is searched for in the directories of PATH.   If  arguments
              are  given, the positional parameters may be used to access them
              while file is being executed.  If no arguments  are  given,  the
              positional  parameters  are those of the environment the command
              is used in.

       : [ ... ]
              The null command.  Exit status is set to zero.

       alias [ -d | +-t [-r] ] [+-px] [+-] [name1[=value1] ...]
              Without arguments,  alias  lists  all  aliases.   For  any  name
              without  a value, the existing alias is listed.  Any name with a
              value defines an alias (see Aliases above).

              When listing aliases, one of  two  formats  is  used:  normally,
              aliases  are  listed  as  name=value,  where value is quoted; if
              options were preceded with + or a lone + is given on the command
              line,  only  name  is printed.  In addition, if the -p option is
              used, each alias is prefixed with the string "alias ".

              The -x option sets (+x clears) the export attribute of an alias,
              or,  if  no  names  are given, lists the aliases with the export
              attribute (exporting an alias has no affect).

              The  -t  option  indicates  that  tracked  aliases  are  to   be
              listed/set (values specified on the command line are ignored for
              tracked aliases).  The -r  option  indicates  that  all  tracked
              aliases are to be reset.

              The  -d  causes  directory  aliases,  which  are  used  in tilde
              expansion, to be listed or set (see Tilde Expansion above).

       bg [job ...]
              Resume the specified stopped job(s) in the  background.   If  no
              jobs  are  specified,  %+  is  assumed.   This  command  is only
              available on systems which support job control.  See Job Control
              below for more information.

       bind [-l] [-m] [key[=editing-command] ...]
              Set   or   view   the   current   emacs   command   editing  key
              bindings/macros.  See Emacs Editing Mode below  for  a  complete

       break [level]
              break  exits the levelth inner most for, select, until, or while
              loop.  level defaults to 1.

       builtin command [arg1 ...]
              Execute the built-in command command.

       cd [-LP] [dir]
              Set the working directory to dir.  If the  parameter  CDPATH  is
              set,  it lists directories to search in for dir.  An empty entry
              in the CDPATH entry means the current directory.  If a non-empty
              directory  from  CDPATH  is  used,  the  resulting  full path is
              printed to  standard  output.   If  dir  is  missing,  the  home
              directory  $HOME  is  used.   If  dir is -, the previous working
              directory is used (see OLDPWD parameter).  If -L option (logical
              path)  is used or if the physical option (see set command below)
              isn't set, references to .. in dir are relative to the path used
              get  to  the directory.  If -P option (physical path) is used or
              if the physical option is set, .. is relative to the  filesystem
              directory  tree.   The  PWD and OLDPWD parameters are updated to
              reflect the current and old wording directory, respectively.

       cd [-LP] old new
              The string new is substituted for old in the current  directory,
              and the shell attempts to change to the new directory.

       command [-pvV] cmd [arg1 ...]
              If  neither  the  -v  nor  -V options are given, cmd is executed
              exactly as if the command  had  not  been  specified,  with  two
              exceptions:  first,  cmd cannot be a shell function, and second,
              special  built-in  commands  lose   their   specialness   (i.e.,
              redirection  and  utility errors do not cause the shell to exit,
              and command assignments are not permanent).  If the -p option is
              given,  a  default  search  path  is used instead of the current
              value of PATH (the actual value of the default  path  is  system
              dependent: on POSIXish systems, it is the value returned by
                                      getconf CS_PATH

              If the -v option is given, instead of executing cmd, information
              about what would be executed is given (and the same is done  for
              arg1  ...):  for  special  and  regular  built-in  commands  and
              functions, their  names  are  simply  printed,  for  aliases,  a
              command  that defines them is printed, and for commands found by
              searching the PATH parameter, the full path of  the  command  is
              printed.  If no command is found, (i.e., the path search fails),
              nothing is printed and command exits  with  a  non-zero  status.
              The -V option is like the -v option, except it is more verbose.

       continue [levels]
              continue  jumps  to the beginning of the levelth inner most for,
              select, until, or while loop.  level defaults to 1.

       echo [-neE] [arg ...]
              Prints  its  arguments  (separated  by  spaces)  followed  by  a
              newline,  to  standard out.  The newline is suppressed if any of
              the arguments contain the  backslash  sequence  \c.   See  print
              command  below  for a list of other backslash sequences that are

              The options  are  provided  for  compatibility  with  BSD  shell
              scripts:   -n   suppresses  the  trailing  newline,  -e  enables
              backslash interpretation (a no-op, since this is normally done),
              and -E suppresses backslash interpretation.

       eval command ...
              The  arguments  are  concatenated  (with spaces between them) to
              form a single string which the shell then parses and executes in
              the current environment.

       exec [command [arg ...]]
              The  command  is  executed  without forking, replacing the shell

              If no arguments are given, any IO redirection is  permanent  and
              the  shell is not replaced.  Any file descriptors greater than 2
              which are opened or dup(2)-ed in this way are not made available
              to other executed commands (i.e., commands that are not built-in
              to the shell).  Note that the Bourne shell differs here: it does
              pass these file descriptors on.

       exit [status]
              The  shell  exits  with the specified exit status.  If status is
              not specified, the exit status is the current  value  of  the  ?

       export [-p] [parameter[=value]] ...
              Sets  the  export  attribute  of the named parameters.  Exported
              parameters are passed in the environment to  executed  commands.
              If values are specified, the named parameters also assigned.

              If no parameters are specified, the names of all parameters with
              the export attribute are printed one per  line,  unless  the  -p
              option  is  used,  in  which  case  export commands defining all
              exported parameters, including their values, are printed.

       false  A command that exits with a non-zero status.

       fc [-e editor | -l [-n]] [-r] [first [last]]
              first and last select commands from the history.   Commands  can
              be  selected  by history number, or a string specifying the most
              recent command starting with that string.  The -l  option  lists
              the  command  on  stdout,  and  -n  inhibits the default command
              numbers.  The -r option reverses the order of the list.  Without
              -l,  the  selected  commands  are edited by the editor specified
              with the -e option,  or  if  no  -e  is  specified,  the  editor
              specified by the FCEDIT parameter (if this parameter is not set,
              /bin/ed is used), and then executed by the shell.

       fc [-e - | -s] [-g] [old=new] [prefix]
              Re-execute  the  selected  command  (the  previous  command   by
              default)  after performing the optional substitution of old with
              new.  If -g is specified, all occurrences of  old  are  replaced
              with  new.  This command is usually accessed with the predefined
              alias r='fc -e -'.

       fg [job ...]
              Resume the specified job(s) in the foreground.  If no  jobs  are
              specified,  %+  is  assumed.   This command is only available on
              systems which support job control.  See Job  Control  below  for
              more information.

       getopts optstring name [arg ...]
              getopts  is  used  by  shell  procedures  to parse the specified
              arguments (or positional parameters, if no arguments are  given)
              and  to  check for legal options.  optstring contains the option
              letters that getopts is to recognize.  If a letter  is  followed
              by a colon, the option is expected to have an argument.  Options
              that do not take arguments may be grouped in a single  argument.
              If  an  option takes an argument and the option character is not
              the last character of the argument it is found in, the remainder
              of the argument is taken to be the option's argument, otherwise,
              the next argument is the option's argument.

              Each time getopts is invoked, it places the next option  in  the
              shell  parameter  name  and the index of the next argument to be
              processed in the shell parameter  OPTIND.   If  the  option  was
              introduced  with a +, the option placed in name is prefixed with
              a +.  When an option requires an argument, getopts places it  in
              the shell parameter OPTARG.  When an illegal option or a missing
              option argument is encountered a question mark  or  a  colon  is
              placed   in  name  (indicating  an  illegal  option  or  missing
              argument,  respectively)  and  OPTARG  is  set  to  the   option
              character  that  caused  the  problem.  An error message is also
              printed to standard error if optstring does  not  begin  with  a

              When the end of the options is encountered, getopts exits with a
              non-zero exit status.  Options end  at  the  first  (non-option)
              argument  that does not start with a -, or when a -- argument is

              Option parsing can be reset by setting OPTIND to 1 (this is done
              automatically  whenever  the  shell  or  a  shell  procedure  is

              Warning: Changing the value of the shell parameter OPTIND  to  a
              value  other  than  1,  or  parsing  different sets of arguments
              without resetting OPTIND may lead to unexpected results.

       hash [-r] [name ...]
              Without arguments, any hashed executable command  pathnames  are
              listed.   The -r option causes all hashed commands to be removed
              from the hash table.  Each name is searched as  if  it  where  a
              command  name and added to the hash table if it is an executable

       jobs [-lpn] [job ...]
              Display information about the specified jobs;  if  no  jobs  are
              specified,  all  jobs  are  displayed.   The  -n  option  causes
              information to be displayed only  for  jobs  that  have  changed
              state  since  the  last notification.  If the -l option is used,
              the process-id of each process in a job is also listed.  The  -p
              option  causes only the process group of each job to be printed.
              See Job Control below for the format of job  and  the  displayed

       kill [-s signame | -signum | -signame ] { job | pid | -pgrp } ...
              Send the specified signal to the specified jobs, process ids, or
              process groups.  If no signal is specified, the signal  TERM  is
              sent.   If  a  job is specified, the signal is sent to the job's
              process group.  See Job Control below for the format of job.

       kill -l [exit-status ...]
              Print the name of the signal that killed a process which  exited
              with   the   specified   exit-statuses.   If  no  arguments  are
              specified, a list of all the signals, their numbers and a  short
              description of them are printed.

       let [expression ...]
              Each  expression is evaluated, see Arithmetic Expressions above.
              If all expressions are successfully evaluated, the  exit  status
              is  0  (1)  if the last expression evaluated to non-zero (zero).
              If an error occurs  during  the  parsing  or  evaluation  of  an
              expression,   the   exit   status  is  greater  than  1.   Since
              expressions may need to be quoted, (( expr )) is syntactic sugar
              for let "expr".

       print [-nprsun | -R [-en]] [argument ...]
              Print  prints its arguments on the standard output, separated by
              spaces, and terminated with a newline.  The -n option suppresses
              the  newline.   By  default,  certain  C escapes are translated.
              These include \b, \f, \n, \r, \t, \v, and \0### (# is  an  octal
              digit, of which there may be 0 to 3).  \c is equivalent to using
              the -n option.  \ expansion may be inhibited with the -r option.
              The  -s  option  prints  to the history file instead of standard
              output, the -u option prints to file descriptor n (n defaults to
              1  if  omitted), and the -p option prints to the co-process (see
              Co-Processes above).

              The -R option is used to emulate, to some degree, the  BSD  echo
              command, which does not process \ sequences unless the -e option
              is given.  As above,  the  -n  option  suppresses  the  trailing

       pwd [-LP]
              Print the present working directory.  If -L option is used or if
              the physical option (see  set  command  below)  isn't  set,  the
              logical  path  is  printed  (i.e.,  the  path  used to cd to the
              current directory).  If -P option (physical path) is used or  if
              the  physical  option  is  set,  the  path  determined  from the
              filesystem (by following ..  directories to the root  directory)
              is printed.

       read [-prsun] [parameter ...]
              Reads  a  line  of  input from standard input, separate the line
              into fields using the IFS parameter  (see  Substitution  above),
              and assign each field to the specified parameters.  If there are
              more parameters than fields, the extra  parameters  are  set  to
              null,   or   alternatively,   if  there  are  more  fields  than
              parameters, the last parameter is assigned the remaining  fields
              (inclusive  of  any  separating  spaces).   If no parameters are
              specified, the REPLY parameter is used.  If the input line  ends
              in a backslash and the -r option was not used, the backslash and
              newline are stripped and more input is read.   If  no  input  is
              read, read exits with a non-zero status.

              The  first  parameter  may  have  a  question  mark and a string
              appended to it, in which case the string is  used  as  a  prompt
              (printed  to  standard  error  before  any input is read) if the
              input is a tty (e.g., read nfoo?'number of foos: ').

              The -un and  -p  options  cause  input  to  be  read  from  file
              descriptor  n  or the current co-process (see Co-Processes above
              for comments on this), respectively.  If the -s option is  used,
              input is saved to the history file.

       readonly [-p] [parameter[=value]] ...
              Sets  the readonly attribute of the named parameters.  If values
              are given,  parameters  are  set  to  them  before  setting  the
              attribute.   Once  a  parameter  is  made readonly, it cannot be
              unset and its value cannot be changed.

              If no parameters are specified, the names of all parameters with
              the  readonly  attribute are printed one per line, unless the -p
              option is used, in which case  readonly  commands  defining  all
              readonly parameters, including their values, are printed.

       return [status]
              Returns  from  a  function or . script, with exit status status.
              If no status is given, the exit  status  of  the  last  executed
              command  is used.  If used outside of a function or . script, it
              has the same effect  as  exit.   Note  that  pdksh  treats  both
              profile  and  $ENV  files  as . scripts, while the original Korn
              shell only treats profiles as . scripts.

       set [+-abCefhkmnpsuvxX] [+-o [option]] [+-A name] [--] [arg ...]
              The set command can be used  to  set  (-)  or  clear  (+)  shell
              options,   set  the  positional  parameters,  or  set  an  array
              parameter.  Options can be changed using the +-o option  syntax,
              where  option  is  the  long  name  of  an  option, or using the
              +-letter syntax, where letter is the option's single letter name
              (not  all  options  have  a  single letter name).  The following
              table lists both option letters (if they exist) and  long  names
              along with a description of what the option does.

               -A                               Sets the elements of the array
                                                parameter name to arg ...;  If
                                                -A is used, the array is reset
                                                (i.e., emptied) first;  if  +A
                                                is  used, the first N elements
                                                are set (where N is the number
                                                of  args),  the  rest are left
               -a         allexport             all new parameters are created
                                                with the export attribute
               -b         notify                Print     job     notification
                                                messages       asynchronously,
                                                instead  of  just  before  the
                                                prompt.   Only  used  if   job
                                                control is enabled (-m).

               -C         noclobber             Prevent   >  redirection  from
                                                overwriting existing files (>|
                                                must   be  used  to  force  an
               -e         errexit               Exit (after executing the  ERR
                                                trap)  as  soon  as  an  error
                                                occurs  or  a  command   fails
                                                (i.e.,  exits  with a non-zero
                                                status).  This does not  apply
                                                to  commands whose exit status
                                                is  explicitly  tested  by   a
                                                shell  construct  such  as if,
                                                until,   while,   &&   or   ||
               -f         noglob                Do   not   expand   file  name
               -h         trackall              Create tracked aliases for all
                                                executed commands (see Aliases
                                                above).   On  by  default  for
                                                non-interactive shells.
               -i         interactive           Enable interactive mode - this
                                                can only be set/unset when the
                                                shell is invoked.
               -k         keyword               Parameter    assignments   are
                                                recognized   anywhere   in   a
               -l         login                 The  shell  is a login shell -
                                                this  can  only  be  set/unset
                                                when the shell is invoked (see
                                                Shell Startup above).
               -m         monitor               Enable  job  control  (default
                                                for interactive shells).
               -n         noexec                Do  not execute any commands -
                                                useful for checking the syntax
                                                of    scripts    (ignored   if
               -p         privileged            Set automatically if, when the
                                                shell  starts, the real uid or
                                                gid   does   not   match   the
                                                effective    uid    or    gid,
                                                respectively.     See    Shell
                                                Startup     above     for    a
                                                description   of   what   this
               -r         restricted            Enable restricted mode -- this
                                                option can only be  used  when
                                                the  shell  is  invoked.   See
                                                Shell  Startup  above  for   a
                                                description   of   what   this
               -s         stdin                 If  used  when  the  shell  is
                                                invoked,   commands  are  read
                                                from  standard   input.    Set
                                                automatically  if the shell is
                                                invoked with no arguments.

                                                When -s is  used  in  the  set
                                                command,    it    causes   the
                                                specified  arguments   to   be
                                                sorted  before  assigning them
                                                to the  positional  parameters
                                                (or  to  array  name, if -A is
               -u         nounset               Referencing   of   an    unset
                                                parameter  is  treated  as  an
                                                error, unless one of the -,  +
                                                or = modifiers is used.
               -v         verbose               Write  shell input to standard
                                                error as it is read.

               -x         xtrace                Print commands  and  parameter
                                                assignments   when   they  are
                                                executed,  preceded   by   the
                                                value of PS4.
               -X         markdirs              Mark    directories   with   a
                                                trailing /  during  file  name
                          bgnice                Background  jobs  are run with
                                                lower priority.
                          braceexpand           Enable brace  expansion  (aka,
                          emacs                 Enable  BRL emacs-like command
                                                line   editing    (interactive
                                                shells    only);   see   Emacs
                                                Editing Mode.
                          emacs-usemeta         In emacs command-line editing,
                                                use  the  8th bit as meta (^[)
                                                prefix.  This is  the  default
                                                if  LC_CTYPE is unset or POSIX
                                                respectively C.  8
                          gmacs                 Enable   gmacs-like   (Gosling
                                                emacs)  command  line  editing
                                                (interactive   shells   only);
                                                currently  identical  to emacs
                                                editing except that  transpose
                                                (^T)       acts       slightly
                          ignoreeof             The shell  will  not  (easily)
                                                exit  on  when  end-of-file is
                                                read, exit must be  used.   To
                                                avoid   infinite   loops,  the
                                                shell will exit if eof is read
                                                13 times in a row.
                          nohup                 Do  not kill running jobs with
                                                a  HUP  signal  when  a  login
                                                shell  exists.   Currently set
                                                by  default,  but  this   will
                                                change  in  the  future  to be
                                                compatible with  the  original
                                                Korn shell (which doesn't have
                                                this option, but does send the
                                                HUP signal).
                          nolog                 No  effect  -  in the original
                                                Korn  shell,   this   prevents
                                                function    definitions   from
                                                being stored  in  the  history
                          physical              Causes the cd and pwd commands
                                                to use `physical'  (i.e.,  the
                                                filesystem's)  ..  directories
                                                instead      of      `logical'
                                                directories  (i.e.,  the shell
                                                handles .., which  allows  the
                                                user   to   be   oblivious  of
                                                symlink links to directories).
                                                Clear  by  default.  Note that
                                                setting this option  does  not
                                                effect  the  current  value of
                                                the PWD parameter; only the cd
                                                command  changes PWD.  See the
                                                cd and pwd commands above  for
                                                more details.
                          posix                 Enable  posix mode.  See POSIX
                                                Mode above.
                          vi                    Enable  vi-like  command  line
                                                editing   (interactive  shells

                          viraw                 No effect -  in  the  original
                                                Korn  shell,  unless viraw was
                                                set, the vi command line  mode
                                                would  let  the  tty driver do
                                                the work until  ESC  (^[)  was
                                                entered.   pdksh  is always in
                                                viraw mode.
                          vi-esccomplete        In vi command line editing, do
                                                command / file name completion
                                                when escape (^[) is entered in
                                                command mode.
                          vi-show8              Prefix   characters  with  the
                                                eighth bit set with `M-'.   If
                                                this   option   is   not  set,
                                                characters   in   the    range
                                                128-160  are  printed  as  is,
                                                which may cause problems.
                          vi-tabcomplete        In vi command line editing, do
                                                command / file name completion
                                                when tab (^I)  is  entered  in
                                                insert   mode.   This  is  the

              These options can also be used upon  invocation  of  the  shell.
              The  current  set  of  options (with single letter names) can be
              found in the parameter -.  set -o with no option name will  list
              all the options and whether each is on or off; set +o will print
              the long names of all options that are currently on.

              Remaining arguments, if any, are positional parameters  and  are
              assigned,  in  order,  to the positional parameters (i.e., 1, 2,
              etc.).  If options are ended with -- and there are no  remaining
              arguments, all positional parameters are cleared.  If no options
              or arguments are  given,  then  the  values  of  all  names  are
              printed.   For  unknown  historical  reasons, a lone - option is
              treated specially: it clears both the -x and -v options.

       shift [number]
              The positional parameters number+1, number+2 etc. are renamed to
              1, 2, etc.  number defaults to 1.

       test expression

       [ expression ]
              test evaluates the expression and returns zero status if true, 1
              if false, and greater than 1 if  there  was  an  error.   It  is
              normally   used  as  the  condition  command  of  if  and  while
              statements.  The following basic expressions are available:

               str                  str has non-zero  length.   Note
                                    that  there is the potential for
                                    problems if str turns out to  be
                                    an  operator  (e.g., -r) - it is
                                    generally better to use  a  test
                                            [ X"str" != X ]
                                    instead  (double quotes are used
                                    in case str contains  spaces  or
                                    file globing characters).
               -r file              file exists and is readable.
               -w file              file exists and is writable.
               -x file              file exists and is executable.
               -a file              file exists.
               -e file              file exists.
               -f file              file is a regular file.
               -d file              file is a directory.
               -c file              file   is  a  character  special
               -b file              file is a block special device.

               -p file              file is a named pipe.
               -u file              file's mode has setuid bit set.
               -g file              file's mode has setgid bit set.
               -k file              file's mode has sticky bit set.
               -s file              file is not empty.
               -O file              file's  owner  is  the   shell's
                                    effective user-ID.
               -G file              file's   group  is  the  shell's
                                    effective group-ID.
               -h file              file is a symbolic link.
               -H file              file  is  a  context   dependent
                                    directory  (only  useful  on HP-
               -L file              file is a symbolic link.
               -S file              file is a socket.
               -o option            shell option  is  set  (see  set
                                    command   above   for   list  of
                                    options).   As  a   non-standard
                                    extension,  if the option starts
                                    with a !, the test  is  negated;
                                    the  test always fails if option
                                    doesn't exist (thus
                                         [ -o foo -o -o !foo ]
                                    returns  true  if  and  only  if
                                    option foo exists).
               file -nt file        first  file is newer than second
                                    file or first  file  exists  and
                                    the second file does not.
               file -ot file        first  file is older than second
                                    file or second file  exists  and
                                    the first file does not.
               file -ef file        first  file  is the same file as
                                    second file.
               -t [fd]              file descriptor is a tty device.
                                    If  the  posix  option  (set  -o
                                    posix, see POSIX Mode above)  is
                                    not  set, fd may be left out, in
                                    which case it is taken to  be  1
                                    (the  behaviour  differs  due to
                                    the    special    POSIX    rules
                                    described below).
               string               string is not empty.
               -z string            string is empty.
               -n string            string is not empty.
               string = string      strings are equal.
               string == string     strings are equal.
               string != string     strings are not equal.
               number -eq number    numbers compare equal.
               number -ne number    numbers compare not equal.
               number -ge number    numbers  compare greater than or
               number -gt number    numbers compare greater than.
               number -le number    numbers  compare  less  than  or
               number -lt number    numbers compare less than.

              The  above  basic  expressions,  in  which  unary operators have
              precedence over binary  operators,  may  be  combined  with  the
              following operators (listed in increasing order of precedence):

               expr -o expr    logical or
               expr -a expr    logical and
               ! expr          logical not
               ( expr )        grouping

              On  operating  systems not supporting /dev/fd/n devices (where n
              is a file descriptor number), the test command will  attempt  to
              fake  it  for  all  tests  that  operate on files (except the -e
              test).  I.e., [ -w /dev/fd/2 ] tests if  file  descriptor  2  is

              Note  that some special rules are applied (courtesy of POSIX) if
              the number of arguments to test or [ ... ] is less than five: if
              leading  ! arguments can be stripped such that only one argument
              remains then a string length test is performed (again,  even  if
              the argument is a unary operator); if leading ! arguments can be
              stripped  such  that  three  arguments  remain  and  the  second
              argument  is  a  binary  operator,  then the binary operation is
              performed (even if first argument is a unary operator, including
              an unstripped !).

              Note:  A  common mistake is to use if [ $foo = bar ] which fails
              if parameter foo is null or unset, if  it  has  embedded  spaces
              (i.e.,  IFS  characters), or if it is a unary operator like ! or
              -n.  Use tests like if [ "X$foo" = Xbar ] instead.

       time [-p] [ pipeline ]
              If a pipeline is given, the times used to execute  the  pipeline
              are reported.  If no pipeline is given, then the user and system
              time used by the shell itself, and all the commands it  has  run
              since  it was started, are reported.  The times reported are the
              real time (elapsed time from start to finish), the user CPU time
              (time  spent running in user mode) and the system CPU time (time
              spent running in kernel mode).  Times are reported  to  standard
              error; the format of the output is:
                  0.00s real     0.00s user     0.00s system
              unless  the  -p  option is given (only possible if pipeline is a
              simple command), in which case the output is slightly longer:
                  real   0.00
                  user   0.00
                  sys    0.00
              (the number of digits after the decimal may vary from system  to
              system).  Note that simple redirections of standard error do not
              effect the output of the time command:
                                   time sleep 1 2> afile
                                 { time sleep 1; } 2> afile
              times for the first command do not go to afile, but those of the
              second command do.

       times  Print  the  accumulated  user and system times used by the shell
              and by processes which have exited that the shell started.

       trap [handler signal ...]
              Sets trap handler that  is  to  be  executed  when  any  of  the
              specified  signals  are  received.   Handler  is  either  a null
              string, indicating the signals are to be ignored, a  minus  (-),
              indicating  that  the  default  action  is  to  be taken for the
              signals (see signal(3)), or a string containing  shell  commands
              to  be  evaluated  and  executed at the first opportunity (i.e.,
              when the current command completes, or before printing the  next
              PS1  prompt) after receipt of one of the signals.  Signal is the
              name of a signal (e.g., PIPE or  ALRM)  or  the  number  of  the
              signal  (see  kill  -l  command  above).   There are two special
              signals: EXIT (also known as 0),  which  is  executed  when  the
              shell is about to exit, and ERR which is executed after an error
              occurs (an error is something that would cause the shell to exit
              if  the -e or errexit option were set -- see set command above).
              EXIT handlers are  executed  in  the  environment  of  the  last
              executed  command.   Note  that  for non-interactive shells, the
              trap handler cannot be changed for  signals  that  were  ignored
              when the shell started.

              With no arguments, trap lists, as a series of trap commands, the
              current state of the traps that have been set  since  the  shell
              started.  Note that the output of trap can not be usefully piped
              to another process (an artifact  of  the  fact  that  traps  are
              cleared when subprocesses are created).

              The original Korn shell's DEBUG trap and the handling of ERR and
              EXIT traps in functions are not yet implemented.

       true   A command that exits with a zero value.

       typeset [[+-Ulprtux] [-L[n]]  [-R[n]]  [-Z[n]]  [-i[n]]  |  -f  [-tux]]
       [name[=value] ...]
              Display  or  set  parameter attributes.  With no name arguments,
              parameter attributes are displayed: if no options arg used,  the
              current  attributes  of  all  parameters  are printed as typeset
              commands; if an option is given (or - with no option letter) all
              parameters  and  their  values with the specified attributes are
              printed; if options are introduced with +, parameter values  are
              not printed.

              If  name  arguments  are  given,  the  attributes  of  the named
              parameters are set (-) or cleared (+).   Values  for  parameters
              may  optionally  be  specified.   If  typeset  is  used inside a
              function,  any  newly  created  parameters  are  local  to   the

              When   -f  is  used,  typeset  operates  on  the  attributes  of
              functions.  As with parameters, if no names are given, functions
              are  listed with their values (i.e., definitions) unless options
              are introduced with +, in which case only the function names are

               -Ln               Left justify attribute: n specifies the field
                                 width.  If n is not  specified,  the  current
                                 width  of  a  parameter  (or the width of its
                                 first assigned value) is used.  Leading white
                                 space (and zeros, if used with the -Z option)
                                 is stripped.  If necessary, values are either
                                 truncated  or  space  padded to fit the field
               -Rn               Right  justify  attribute:  n  specifies  the
                                 field  width.   If  n  is  not specified, the
                                 current width of a parameter (or the width of
                                 its  first assigned value) is used.  Trailing
                                 white  space  are  stripped.   If  necessary,
                                 values   are   either   stripped  of  leading
                                 characters or space padded to make  them  fit
                                 the field width.
               -Zn               Zero fill attribute: if not combined with -L,
                                 this is the same as -R, except  zero  padding
                                 is used instead of space padding.
               -in               integer  attribute:  n  specifies the base to
                                 use  when  displaying  the  integer  (if  not
                                 specified,   the  base  given  in  the  first
                                 assignment is used).   Parameters  with  this
                                 attribute  may  be assigned values containing
                                 arithmetic expressions.
               -U                unsigned  integer  attribute:  integers   are
                                 printed  as unsigned values (only useful when
                                 combined with the -i option).  This option is
                                 not in the original Korn shell.
               -f                Function  mode:  display or set functions and
                                 their attributes, instead of parameters.
               -l                Lower  case  attribute:   all    upper   case
                                 characters  in  values are converted to lower
                                 case.  (In  the  original  Korn  shell,  this
                                 parameter meant `long integer' when used with
                                 the -i option).
               -p                Print complete typeset commands that  can  be
                                 used to re-create the attributes (but not the
                                 values) of parameters.  This is  the  default
                                 action     (option     exists    for    ksh93
               -r                Readonly attribute: parameters with the  this
                                 attribute  may  not  be assigned to or unset.
                                 Once this attribute is set,  it  can  not  be
                                 turned off.

               -t                Tag  attribute:  has no meaning to the shell;
                                 provided for application use.

                                 For functions, -t  is  the  trace  attribute.
                                 When  functions  with the trace attribute are
                                 executed, the xtrace  (-x)  shell  option  is
                                 temporarily turned on.
               -u                Upper   case   attribute:   all   lower  case
                                 characters in values are converted  to  upper
                                 case.   (In  the  original  Korn  shell, this
                                 parameter meant `unsigned integer' when  used
                                 with  the  -i  option, which meant upper case
                                 letters would never be used for bases greater
                                 than 10.  See the -U option).

                                 For functions, -u is the undefined attribute.
                                 See Functions above for the  implications  of
               -x                Export  attribute:  parameters (or functions)
                                 are placed in the environment of any executed
                                 commands.    Exported   functions   are   not
                                 implemented yet.

       ulimit [-abcdfHlmnpsStvw] [value]
              Display or set process limits.  If no options are used, the file
              size  limit (-f) is assumed.  value, if specified, may be either
              be an arithmetic expression or the word unlimited.   The  limits
              affect  the shell and any processes created by the shell after a
              limit is imposed.  Note that some systems may not  allow  limits
              to  be increased once they are set.  Also note that the types of
              limits available are system dependent - some systems  have  only
              the -f limit.

              -a     Displays  all  limits; unless -H is used, soft limits are

              -H     Set the hard limit only (default is to set both hard  and
                     soft limits).

              -S     Set  the soft limit only (default is to set both hard and
                     soft limits).

              -b     Impose a size limit of n bytes  on  the  size  of  socket

              -c     Impose  a  size  limit  of  n  blocks on the size of core

              -d     Impose a size limit of n kbytes on the size of  the  data

              -f     Impose  a  size limit of n blocks on files written by the
                     shell and its child processes (files of any size  may  be

              -l     Impose  a  limit  of  n  kbytes  on  the amount of locked
                     (wired) physical memory.

              -m     Impose a limit of n kbytes  on  the  amount  of  physical
                     memory used.

              -n     Impose  a limit of n file descriptors that can be open at

              -p     Impose a limit of n processes that can be run by the user
                     at any one time.

              -s     Impose  a size limit of n kbytes on the size of the stack

              -t     Impose a time limit of n CPU seconds to be used  by  each

              -v     Impose  a  limit  of  n  kbytes  on the amount of virtual
                     memory  used;  on  some  systems  this  is  the   maximum
                     allowable virtual address (in bytes, not kbytes).

              -w     Impose  a  limit  of n kbytes on the amount of swap space

              As far as ulimit is concerned, a block is 512 bytes.

       umask [-S] [mask]
              Display or set the file permission creation mask, or umask  (see
              umask(2)).   If the -S option is used, the mask displayed or set
              is symbolic, otherwise it is an octal number.

              Symbolic masks are like those used by chmod(1):
              in which the first group of characters  is  the  who  part,  the
              second  group  is  the  op  part, and the last group is the perm
              part.  The who part specifies which part of the umask is  to  be
              modified.  The letters mean:

                     u      the user permissions

                     g      the group permissions

                     o      the other permissions (non-user, non-group)

                     a      all permissions (user, group and other)

              The  op  part  indicates  how  the  who  permissions  are  to be

                     =      set

                     +      added to

                     -      removed from

              The perm part specifies which permissions are to be  set,  added
              or removed:

                     r      read permission

                     w      write permission

                     x      execute permission

              When symbolic masks are used, they describe what permissions may
              be made available (as opposed to octal masks in which a set  bit
              means  the  corresponding  bit  is  to  be  cleared).   Example:
              `ug=rwx,o=' sets  the  mask  so  files  will  not  be  readable,
              writable  or  executable by `others', and is equivalent (on most
              systems) to the octal mask `07'.

       unalias [-adt] [name1 ...]
              The aliases for the given names are removed.  If the  -a  option
              is  used,  all aliases are removed.  If the -t or -d options are
              used, the indicated operations are carried  out  on  tracked  or
              directory aliases, respectively.

       unset [-fv] parameter ...
              Unset  the named parameters (-v, the default) or functions (-f).
              The exit status is  non-zero  if  any  of  the  parameters  were
              already unset, zero otherwise.

       wait [job]
              Wait  for  the  specified  job(s) to finish.  The exit status of
              wait is that of the last specified  job:  if  the  last  job  is
              killed  by  a signal, the exit status is 128 + the number of the
              signal (see kill -l exit-status above); if  the  last  specified
              job  can't  be  found  (because it never existed, or had already
              finished), the exit status of wait  is  127.   See  Job  Control
              below  for  the format of job.  Wait will return if a signal for
              which a trap has been set is received, or if a HUP, INT or  QUIT
              signal is received.

              If  no  jobs are specified, wait waits for all currently running
              jobs (if any) to finish and exits with a zero  status.   If  job
              monitoring  is enabled, the completion status of jobs is printed
              (this is not the case when jobs are explicitly specified).

       whence [-pv] [name ...]
              For each name, the type of command  is  listed  (reserved  word,
              built-in, alias, function, tracked alias or executable).  If the
              -p option is used, a path search done even if name is a reserved
              word,  alias,  etc.  Without the -v option, whence is similar to
              command -v except that whence will find reserved words and won't
              print  aliases  as alias commands; with the -v option, whence is
              the same as command -V.  Note that for  whence,  the  -p  option
              does  not  affect  the search path used, as it does for command.
              If the type of one or more of the names could not be determined,
              the exit status is non-zero.

   Job Control
       Job  control refers to the shell's ability to monitor and control jobs,
       which are processes or groups of  processes  created  for  commands  or
       pipelines.   At  a  minimum, the shell keeps track of the status of the
       background  (i.e.,  asynchronous)  jobs  that  currently  exist;   this
       information can be displayed using the jobs command.  If job control is
       fully enabled  (using  set  -m  or  set  -o  monitor),  as  it  is  for
       interactive  shells,  the  processes  of  a job are placed in their own
       process group, foreground jobs can be stopped  by  typing  the  suspend
       character  from  the  terminal  (normally ^Z), jobs can be restarted in
       either the foreground or background, using  the  fg  and  bg  commands,
       respectively, and the state of the terminal is saved or restored when a
       foreground job is stopped or restarted, respectively.

       Note that only  commands  that  create  processes  (e.g.,  asynchronous
       commands,  subshell  commands, and non-built-in, non-function commands)
       can be stopped; commands like read cannot be.

       When a job is created, it is assigned a  job-number.   For  interactive
       shells, this number is printed inside [..], followed by the process-ids
       of the processes in the job when an asynchronous command is run.  A job
       may  be  referred  to in bg, fg, jobs, kill and wait commands either by
       the process id of the last process in the command pipeline  (as  stored
       in the $! parameter) or by prefixing the job-number with a percent sign
       (%).  Other percent sequences can also be used to refer to jobs:

        %+                       The most recently stopped job, or,  if  there
                                 are no stopped jobs, the oldest running job.
        %%, %                    Same as %+.
        %-                       The  job  that  would  be  the %+ job, if the
                                 later did not exist.
        %n                       The job with job-number n.
        %?string                 The job  containing  the  string  string  (an
                                 error occurs if multiple jobs are matched).
        %string                  The job starting with string string (an error
                                 occurs if multiple jobs are matched).

       When a job changes state (e.g., a background job finishes or foreground
       job is stopped), the shell prints the following status information:
              [number] flag status command

              is the job-number of the job.

        flag  is + or - if the job is the %+ or %- job, respectively, or space
              if it is neither.

              indicates the current state of the job and can be

                     the job has neither stopped or exited (note that  running
                     does  not  necessarily  mean  consuming  CPU  time -- the
                     process could be blocked waiting for some event).

              Done [(number)]
                     the job exited.  number is the exit status  of  the  job,
                     which is omitted if the status is zero.

              Stopped [(signal)]
                     the job was stopped by the indicated signal (if no signal
                     is given, the job was stopped by SIGTSTP).

              signal-description [(core dumped)]
                     the job was  killed  by  a  signal  (e.g.,  Memory fault,
                     Hangup,  etc.  --  use  kill  -l  for  a  list  of signal
                     descriptions).  The (core dumped) message  indicates  the
                     process created a core file.

              is  the command that created the process.  If there are multiple
              processes in the job, then each process will have a line showing
              its command and possibly its status, if it is different from the
              status of the previous process.

       When an attempt is made to exit the shell while there are jobs  in  the
       stopped state, the shell warns the user that there are stopped jobs and
       does not exit.  If another attempt is  immediately  made  to  exit  the
       shell,  the  stopped  jobs  are  sent a HUP signal and the shell exits.
       Similarly, if the nohup option is not set and there  are  running  jobs
       when an attempt is made to exit a login shell, the shell warns the user
       and does not exit.  If another attempt is immediately made to exit  the
       shell, the running jobs are sent a HUP signal and the shell exits.

   Interactive Input Line Editing
       The  shell  supports three modes of reading command lines from a tty in
       an interactive session.  Which is used  is  controlled  by  the  emacs,
       gmacs and vi set options (at most one of these can be set at once).  If
       none of these options is enabled, the shell simply  reads  lines  using
       the  normal tty driver.  If the emacs or gmacs option is set, the shell
       allows emacs like editing of the command; similarly, if the  vi  option
       is  set,  the shell allows vi like editing of the command.  These modes
       are described in detail in the following sections.

       In these editing modes, if a line is longer that the screen width  (see
       COLUMNS  parameter),  a  >,  +  or < character is displayed in the last
       column indicating that there are  more  characters  after,  before  and
       after,  or  before  the  current  position,  respectively.  The line is
       scrolled horizontally as necessary.

   Emacs Editing Mode
       When the emacs  option  is  set,  interactive  input  line  editing  is
       enabled.   Warning: This mode is slightly different from the emacs mode
       in the original Korn shell and the 8th bit is stripped in  emacs  mode.
       In  this  mode various editing commands (typically bound to one or more
       control characters) cause immediate actions without waiting for a  new-
       line.   Several  editing  commands  are  bound  to  particular  control
       characters when the shell is invoked; these  bindings  can  be  changed
       using the following commands:

       bind   The current bindings are listed.

       bind string=[editing-command]
              The  specified  editing  command  is  bound to the given string,
              which should consist  of  a  control  character  (which  may  be
              written  using caret notation ^X), optionally preceded by one of
              the two prefix characters.  Future  input  of  the  string  will
              cause  the editing command to be immediately invoked.  Note that
              although only two prefix characters (usually  ESC  and  ^X)  are
              supported, some multi-character sequences can be supported.  The
              following binds the arrow keys on an  ANSI  terminal,  or  xterm
              (these  are  in  the  default  bindings).  Of course some escape
              sequences won't work out quite this nicely:

              bind '^[['=prefix-2
              bind '^XA'=up-history
              bind '^XB'=down-history
              bind '^XC'=forward-char
              bind '^XD'=backward-char

       bind -l
              Lists the names of the functions to which keys may be bound.

       bind -m string=[substitute]
              The  specified  input  string  will  afterwards  be  immediately
              replaced  by  the  given  substitute  string,  which may contain
              editing commands.

       The  following  is  a  list  of  editing  commands   available.    Each
       description  starts  with  the name of the command, a n, if the command
       can be prefixed with a count, and any keys the command is bound  to  by
       default  (written  using  caret  notation, e.g., ASCII ESC character is
       written as ^[).  A count prefix for a  command  is  entered  using  the
       sequence  ^[n,  where  n  is  a  sequence  of  1 or more digits; unless
       otherwise specified, if a count is omitted, it  defaults  to  1.   Note
       that  editing  command  names  are  used  only  with  the bind command.
       Furthermore, many editing commands are useful only on terminals with  a
       visible   cursor.    The  default  bindings  were  chosen  to  resemble
       corresponding EMACS key bindings.   The  users  tty  characters  (e.g.,
       ERASE)  are  bound  to  reasonable substitutes and override the default

       abort ^G
              Useful as a response to a request for a  search-history  pattern
              in order to abort the search.

       auto-insert n
              Simply  causes  the  character to appear as literal input.  Most
              ordinary characters are bound to this.

       backward-char  n ^B
              Moves the cursor backward n characters.

       backward-word  n ^[B
              Moves the cursor backward to the  beginning  of  a  word;  words
              consist of alphanumerics, underscore (_) and dollar ($).

       beginning-of-history ^[<
              Moves to the beginning of the history.

       beginning-of-line ^A
              Moves the cursor to the beginning of the edited input line.

       capitalize-word n ^[c, ^[C
              Uppercase  the  first character in the next n words, leaving the
              cursor past the end of the last word.  If the current line  does
              not  begin  with  a  comment  character,  one  is  added  at the
              beginning of the line and the line is entered (as if return  had
              been  pressed),  otherwise  the  existing comment characters are
              removed and the cursor is placed at the beginning of the line.

       complete ^[^[

       complete ^I
              Automatically completes as much as is unique of the command name
              or the file name containing the cursor.  If the entire remaining
              command or file name is unique a  space  is  printed  after  its
              completion,  unless  it  is  a directory name in which case / is
              appended.  If there is no command or file name with the  current
              partial  word as its prefix, a bell character is output (usually
              causing a audio beep).

       complete-command ^X^[
              Automatically completes as much as is unique of the command name
              having  the  partial  word up to the cursor as its prefix, as in
              the complete command described above.

       complete-file ^[^X
              Automatically completes as much as is unique of  the  file  name
              having  the  partial  word up to the cursor as its prefix, as in
              the complete command described above.

       complete-list ^[=
              List the possible completions for the current word.

       delete-char-backward n ERASE, ^?, ^H
              Deletes n characters before the cursor.

       delete-char-forward n
              Deletes n characters after the cursor.

       delete-word-backward n ^[ERASE, ^[^?, ^[^H, ^[h
              Deletes n words before the cursor.

       delete-word-forward n ^[d
              Deletes characters after the cursor up to the end of n words.

       down-history n ^N
              Scrolls the history buffer forward n lines (later).  Each  input
              line  originally starts just after the last entry in the history
              buffer, so down-history  is  not  useful  until  either  search-
              history or up-history has been performed.

       downcase-word n ^[L, ^[l
              Lowercases the next n words.

       end-of-history ^[>
              Moves to the end of the history.

       end-of-line ^E
              Moves the cursor to the end of the input line.

       eot ^_ Acts  as  an end-of-file; this is useful because edit-mode input
              disables normal terminal input canonicalization.

       eot-or-delete n ^D
              Acts as eot if alone on a line; otherwise acts  as  delete-char-

       error  Error (ring the bell).

       exchange-point-and-mark ^X^X
              Places  the cursor where the mark is, and sets the mark to where
              the cursor was.

       expand-file ^[*
              Appends a * to the current word and replaces the word  with  the
              result  of  performing  file  globbing on the word.  If no files
              match the pattern, the bell is rung.

       forward-char n ^F
              Moves the cursor forward n characters.

       forward-word n ^[f
              Moves the cursor forward to the end of the nth word.

       goto-history n ^[g
              Goes to history number n.

       kill-line KILL
              Deletes the entire input line.

       kill-region ^W
              Deletes the input between the cursor and the mark.

       kill-to-eol n ^K
              Deletes the input from the cursor to the end of the line if n is
              not  specified,  otherwise deletes characters between the cursor
              and column n.

       list ^[?
              Prints a sorted, columnated list of command names or file  names
              (if  any)  that  can  complete  the  partial word containing the
              cursor.  Directory names have / appended to them.

       list-command ^X?
              Prints a sorted, columnated list of command names (if any)  that
              can complete the partial word containing the cursor.

       list-file ^X^Y
              Prints a sorted, columnated list of file names (if any) that can
              complete the partial word  containing  the  cursor.   File  type
              indicators are appended as described under list above.

       newline ^J, ^M
              Causes the current input line to be processed by the shell.  The
              current cursor position may be anywhere on the line.

       newline-and-next ^O
              Causes the current input line to be processed by the shell,  and
              the  next  line  from history becomes the current line.  This is
              only useful after an up-history or search-history.

       no-op QUIT
              This does nothing.

       prefix-1 ^[
              Introduces a 2-character command sequence.

       prefix-2 ^X

       prefix-2 ^[[
              Introduces a 2-character command sequence.

       prev-hist-word n ^[., ^[_
              The last (nth) word of the previous command is inserted  at  the

       quote ^^
              The  following  character  is  taken literally rather than as an
              editing command.

       redraw ^L
              Reprints the prompt string and the current input line.

       search-character-backward n ^[^]
              Search backward in the current line for the  nth  occurrence  of
              the next character typed.

       search-character-forward n ^]
              Search forward in the current line for the nth occurrence of the
              next character typed.

       search-history ^R
              Enter incremental search mode.  The  internal  history  list  is
              searched  backwards for commands matching the input.  An initial
              ^ in the search string anchors the search.  The abort  key  will
              leave  search  mode.   Other  commands  will  be  executed after
              leaving  search  mode.    Successive   search-history   commands
              continue  searching  backward to the next previous occurrence of
              the pattern.  The history buffer retains only a finite number of
              lines; the oldest are discarded as necessary.

       set-mark-command ^[<space>
              Set the mark at the cursor position.

       stuff  On  systems  supporting it, pushes the bound character back onto
              the terminal input where it may receive  special  processing  by
              the terminal handler.  This is useful for the BRL ^T mini-systat
              feature, for example.

              Acts like stuff, then aborts input the same as an interrupt.

       transpose-chars ^T
              If at the end of line, or if  the  gmacs  option  is  set,  this
              exchanges  the  two previous characters; otherwise, it exchanges
              the previous and current characters and  moves  the  cursor  one
              character to the right.

       up-history n ^P
              Scrolls the history buffer backward n lines (earlier).

       upcase-word n ^[U, ^[u
              Uppercases the next n words.

       version ^V
              Display the version of ksh.  The current edit buffer is restored
              as soon as any key is pressed (the key is then processed, unless
              it is a space).

       yank ^Y
              Inserts  the  most  recently  killed  text string at the current
              cursor position.

       yank-pop ^[y
              Immediately after a yank, replaces the inserted text string with
              the next previous killed text string.

   Vi Editing Mode
       The  vi  command  line editor in ksh has basically the same commands as
       the vi editor (see vi(1)), with the following exceptions:

         o    you start out in insert mode,

         o    there are file name and command completion commands  (=,  \,  *,
              ^X, ^E, ^F and, optionally, <tab>),

         o    the  _  command  is  different  (in  ksh it is the last argument
              command, in vi it goes to the start of the current line),

         o    the / and G commands move in the opposite  direction  as  the  j

         o    and  commands which don't make sense in a single line editor are
              not available (e.g., screen movement commands,  ex  :  commands,

       Note  that  the  ^X stands for control-X; also <esc>, <space> and <tab>
       are used for escape, space and tab, respectively (no kidding).

       Like vi, there are two modes: insert mode and command mode.  In  insert
       mode,  most  characters  are  simply  put  in the buffer at the current
       cursor position as they are typed, however, some characters are treated
       specially.   In  particular,  the  following  characters are taken from
       current tty settings (see stty(1)) and have their usual meaning (normal
       values  are  in  parentheses):  kill (^U), erase (^?), werase (^W), eof
       (^D), intr (^C) and quit (^\).  In addition to the above, the following
       characters are also treated specially in insert mode:

        ^H                       erases previous character
        ^V                       literal next: the next character typed is not
                                 treated specially (can be used to insert  the
                                 characters being described here)
        ^J ^M                    end of line: the current line is read, parsed
                                 and executed by the shell
        <esc>                    puts the editor in command mode (see below)
        ^E                       command and file name enumeration (see below)
        ^F                       command and file name completion (see below).
                                 If  used twice in a row, the list of possible
                                 completions is displayed;  if  used  a  third
                                 time, the completion is undone.
        ^X                       command and file name expansion (see below)
        <tab>                    optional  file  name  and  command completion
                                 (see ^F  above),  enabled  with  set  -o  vi-

       In   command   mode,  each  character  is  interpreted  as  a  command.
       Characters that don't correspond to commands, are illegal  combinations
       of  commands or are commands that can't be carried out all cause beeps.
       In the following command descriptions, a n indicates the command may be
       prefixed  by  a  number  (e.g.,  10l  moves right 10 characters); if no
       number prefix is used, n is assumed to be 1 unless otherwise specified.
       The  term  `current position' refers to the position between the cursor
       and the character preceding the cursor.  A  `word'  is  a  sequence  of
       letters,  digits and underscore characters or a sequence of non-letter,
       non-digit, non-underscore,  non-white-space  characters  (e.g.,  ab2*&^
       contains  two  words) and a `big-word' is a sequence of non-white-space

       Special ksh vi commands
              The following commands are not in, or are  different  from,  the
              normal vi file editor:

              n_     insert a space followed by the nth big-word from the last
                     command in the history at the current position and  enter
                     insert  mode;  if  n  is  not specified, the last word is

              #      insert the comment character (#)  at  the  start  of  the
                     current line and return the line to the shell (equivalent
                     to I#^J).

              ng     like G, except if n is not specified, it goes to the most
                     recent remembered line.

              nv     edit  line  n using the vi editor; if n is not specified,
                     the current line is edited.  The actual command  executed
                     is `fc -e ${VISUAL:-${EDITOR:-vi}} n'.

              * and ^X
                     command  or file name expansion is applied to the current
                     big-word (with an appended *, if  the  word  contains  no
                     file  globing characters) - the big-word is replaced with
                     the resulting words.  If  the  current  big-word  is  the
                     first  on  the  line  (or  follows  one  of the following
                     characters: ;, |, &, (, )) and does not contain  a  slash
                     (/)  then  command expansion is done, otherwise file name
                     expansion is done.  Command expansion will match the big-
                     word against all aliases, functions and built-in commands
                     as well as any executable files found  by  searching  the
                     directories  in  the PATH parameter.  File name expansion
                     matches the big-word against the  files  in  the  current
                     directory.   After  expansion,  the cursor is placed just
                     past the last word and the editor is in insert mode.

              n\, n^F, n<tab> and n<esc>
                     command/file name completion: replace  the  current  big-
                     word   with  the  longest  unique  match  obtained  after
                     performing command/file name expansion.   <tab>  is  only
                     recognized  if  the  vi-tabcomplete  option is set, while
                     <esc> is only recognized if the vi-esccomplete option  is
                     set  (see  set  -o).  If n is specified, the nth possible
                     completion is selected (as reported by  the  command/file
                     name enumeration command).

              = and ^E
                     command/file  name  enumeration: list all the commands or
                     files that match the current big-word.

              ^V     display the version  of  pdksh;  it  is  displayed  until
                     another key is pressed (this key is ignored).

              @c     macro  expansion: execute the commands found in the alias

       Intra-line movement commands

              nh and n^H
                     move left n characters.

              nl and n<space>
                     move right n characters.

              0      move to column 0.

              ^      move to the first non white-space character.

              n|     move to column n.

              $      move to the last character.

              nb     move back n words.

              nB     move back n big-words.

              ne     move forward to the end the word, n times.

              nE     move forward to the end the big-word, n times.

              nw     move forward n words.

              nW     move forward n big-words.

              %      find match: the editor  looks  forward  for  the  nearest
                     parenthesis,  bracket  or brace and then moves the to the
                     matching parenthesis, bracket or brace.

              nfc    move forward to the nth occurrence of the character c.

              nFc    move backward to the nth occurrence of the character c.

              ntc    move forward to just before the  nth  occurrence  of  the
                     character c.

              nTc    move  backward  to  just before the nth occurrence of the
                     character c.

              n;     repeats the last f, F, t or T command.

              n,     repeats the last f, F, t or T command, but moves  in  the
                     opposite direction.

       Inter-line movement commands

              nj and n+ and n^N
                     move to the nth next line in the history.

              nk and n- and n^P
                     move to the nth previous line in the history.

              nG     move to line n in the history; if n is not specified, the
                     number first remembered line is used.

              ng     like G, except if n is not specified, it goes to the most
                     recent remembered line.

                     search  backward  through  the  history  for the nth line
                     containing string; if string starts with ^, the remainder
                     of  the  string  must  appear at the start of the history
                     line for it to match.

                     same  as  /,  except  it  searches  forward  through  the

              nn     search  for the nth occurrence of the last search string;
                     the direction of the search  is  the  same  as  the  last

              nN     search  for the nth occurrence of the last search string;
                     the direction of the search is the opposite of  the  last

       Edit commands

              na     append text n times: goes into insert mode just after the
                     current position.   The  append  is  only  replicated  if
                     command mode is re-entered (i.e., <esc> is used).

              nA     same as a, except it appends at the end of the line.

              ni     insert text n times: goes into insert mode at the current
                     position.  The insertion is only  replicated  if  command
                     mode is re-entered (i.e., <esc> is used).

              nI     same  as  i, except the insertion is done just before the
                     first non-blank character.

              ns     substitute  the  next  n  characters  (i.e.,  delete  the
                     characters and go into insert mode).

              S      substitute whole line: all characters from the first non-
                     blank character to the end of line are deleted and insert
                     mode is entered.

                     change   from   the  current  position  to  the  position
                     resulting from n move-cmds (i.e.,  delete  the  indicated
                     region  and  go  into insert mode); if move-cmd is c, the
                     line starting  from  the  first  non-blank  character  is

              C      change  from  the current position to the end of the line
                     (i.e., delete to the end of the line and go  into  insert

              nx     delete the next n characters.

              nX     delete the previous n characters.

              D      delete to the end of the line.

                     delete   from   the  current  position  to  the  position
                     resulting  from  n  move-cmds;  move-cmd  is  a  movement
                     command  (see above) or d, in which case the current line
                     is deleted.

              nrc    replace the next n characters with the character c.

              nR     replace:  enter  insert  mode  but   overwrite   existing
                     characters   instead   of   inserting   before   existing
                     characters.  The replacement is repeated n times.

              n~     change the case of the next n characters.

                     yank from the current position to the position  resulting
                     from  n move-cmds into the yank buffer; if move-cmd is y,
                     the whole line is yanked.

              Y      yank from the current position to the end of the line.

              np     paste the contents of the  yank  buffer  just  after  the
                     current position, n times.

              nP     same  as  p,  except  the buffer is pasted at the current

       Miscellaneous vi commands

              ^J and ^M
                     the current line is read,  parsed  and  executed  by  the

              ^L and ^R
                     redraw the current line.

              n.     redo the last edit command n times.

              u      undo the last edit command.

              U      undo all changes that have been made to the current line.

              intr and quit
                     the  interrupt  and  quit  terminal  characters cause the
                     current line to  be  deleted  and  a  new  prompt  to  be


       Any  bugs  in  pdksh  should  be  reported  to  Please
       include the version of pdksh (echo $KSH_VERSION shows it), the machine,
       operating system and compiler you are using and a description of how to
       repeat the bug (a small shell  script  that  demonstrates  the  bug  is
       best).  The following, if relevant (if you are not sure, include them),
       can also helpful: options you are using (both options.h options and set
       -o  options)  and  a  copy  of your config.h (the file generated by the
       configure  script).   New  versions  of  pdksh  can  be  obtained  from

       BTW, the most frequently reported bug is
               echo hi | read a; echo $a   # Does not print hi
       I'm aware of this and there is no need to report it.

       This page documents version
                            @(#)PD KSH v5.2.14 99/07/13.2
       of the public domain korn shell.

       This shell is based on the public domain 7th edition Bourne shell clone
       by Charles Forsyth and parts of the BRL shell by  Doug  A.  Gwyn,  Doug
       Kingston,  Ron  Natalie,  Arnold  Robbins, Lou Salkind and others.  The
       first  release  of  pdksh  was  created  by  Eric  Gisin,  and  it  was
       subsequently  maintained  by John R. MacMillan (chance!,
       and Simon J. Gerraty (  The current  maintainer  is
       Michael  Rendell  (   The  CONTRIBUTORS  file in the
       source distribution contains a more complete list of people  and  their
       part in the shell's development.

       awk(1),  sh(1),  csh(1), ed(1), getconf(1), getopt(1), sed(1), stty(1),
       vi(1),  dup(2),  execve(2),  getgid(2),  getuid(2),  open(2),  pipe(2),
       wait(2), getopt(3), rand(3), signal(3), system(3), environ(7)

       The KornShell Command and Programming Language, Morris Bolsky and David
       Korn, 1989, ISBN 0-13-516972-0.

       UNIX Shell Programming, Stephen G. Kochan, Patrick H. Wood, Hayden.

       IEEE Standard for information Technology -  Portable  Operating  System
       Interface  (POSIX)  - Part 2: Shell and Utilities, IEEE Inc, 1993, ISBN

                                August 19, 1996                         KSH(1)