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FTW(3)                   BSD Library Functions Manual                   FTW(3)

     ftw, nftw -- traverse (walk) a file tree

     #include <ftw.h>

     ftw(const char *path, int (*fn)(const char *, const struct stat *, int),
         int maxfds);

     nftw(const char *path,
         int (*fn)(const char *, const struct stat *, int, struct FTW *),
         int maxfds, int flags);

     These functions are provided for compatibility with legacy code.  New
     code should use the fts(3) functions.

     The ftw() and nftw() functions traverse (walk) the directory hierarchy
     rooted in path.  For each object in the hierarchy, these functions call
     the function pointed to by fn.  The ftw() function passes this function a
     pointer to a NUL-terminated string containing the name of the object, a
     pointer to a stat structure corresponding to the object, and an integer
     flag.  The nftw() function passes the aforementioned arguments plus a
     pointer to a FTW structure as defined by <ftw.h> (shown below):

     struct FTW {
         int base;   /* offset of basename into pathname */
         int level;  /* directory depth relative to starting point */

     Possible values for the flag passed to fn are:

     FTW_F    A regular file.

     FTW_D    A directory being visited in pre-order.

     FTW_DNR  A directory which cannot be read.  The directory will not be
              descended into.

     FTW_DP   A directory being visited in post-order (nftw() only).

     FTW_NS   A file for which no stat(2) information was available.  The
              contents of the stat structure are undefined.

     FTW_SL   A symbolic link.

     FTW_SLN  A symbolic link with a non-existent target (nftw() only).

     The ftw() function traverses the tree in pre-order.  That is, it
     processes the directory before the directory's contents.

     The maxfds argument specifies the maximum number of file descriptors to
     keep open while traversing the tree.  It has no effect in this

     The nftw() function has an additional flags argument with the following
     possible values:

     FTW_PHYS   Physical walk, don't follow symbolic links.

     FTW_MOUNT  The walk will not cross a mount point.

     FTW_DEPTH  Process directories in post-order.  Contents of a directory
                are visited before the directory itself.  By default, nftw()
                traverses the tree in pre-order.

     FTW_CHDIR  Change to a directory before reading it.  By default, nftw()
                will change its starting directory.  The current working
                directory will be restored to its original value before nftw()

     If the tree was traversed successfully, the ftw() and nftw() functions
     return 0.  If the function pointed to by fn returns a non-zero value,
     ftw() and nftw() will stop processing the tree and return the value from
     fn.  Both functions return -1 if an error is detected.

     The ftw() and nftw() functions may fail and set errno for any of the
     errors specified for the library functions close(2), open(2), stat(2),
     malloc(3), opendir(3), and readdir(3).  If the FGTW_CHDIR flag is set,
     the nftw() function may fail and set errno for any of the errors
     specified for chdir(2).  In addition, either function may fail and set
     errno as follows:

     [EINVAL]           The maxfds argument is less than 1 or greater than

     chdir(2), close(2), open(2), stat(2), fts(3), malloc(3), opendir(3),

     The ftw() and nftw() functions conform to IEEE Std 1003.1-2001
     ("POSIX.1").  The IEEE Std 1003.1-2008 ("POSIX.1") revision marked the
     function ftw() as obsolete.

     The maxfds argument is currently ignored.

BSD                             April 30, 2010                             BSD