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FILEFUNCS(3am)                      GNU Awk Extension Modules                      FILEFUNCS(3am)

NAME
       filefuncs - provide some file related functionality to gawk

SYNOPSIS
       @load "filefuncs"

       result = chdir("/some/directory")

       result = stat("/some/path", statdata [, follow])

       flags = or(FTS_PHYSICAL, ...)
       result = fts(pathlist, flags, filedata)

DESCRIPTION
       The filefuncs extension adds several functions that provide access to file-related facili‐
       ties.

   chdir()
       The chdir() function is a direct hook to the chdir(2) system call to  change  the  current
       directory.  It returns zero upon success or less than zero upon error.  In the latter case
       it updates ERRNO.

   stat()
       The stat() function provides a hook into the stat(2) system call.  It  returns  zero  upon
       success  or  less than zero upon error.  In the latter case it updates ERRNO.  By default,
       it uses lstat(2).  However, if passed a third argument, it uses stat(2), instead.

       In all cases, it clears the statdata array.  When the call is successful, stat() fills the
       statdata array with information retrieved from the filesystem, as follows:

       statdata["name"]
              The name of the file.

       statdata["dev"]
              Corresponds to the st_dev field in the struct stat.

       statdata["ino"]
              Corresponds to the st_ino field in the struct stat.

       statdata["mode"]
              Corresponds to the st_mode field in the struct stat.

       statdata["nlink"]
              Corresponds to the st_nlink field in the struct stat.

       statdata["uid"]
              Corresponds to the st_uid field in the struct stat.

       statdata["gid"]
              Corresponds to the st_gid field in the struct stat.

       statdata["size"]
              Corresponds to the st_size field in the struct stat.

       statdata["atime"]
              Corresponds to the st_atime field in the struct stat.

       statdata["mtime"]
              Corresponds to the st_mtime field in the struct stat.

       statdata["ctime"]
              Corresponds to the st_ctime field in the struct stat.

       statdata["rdev"]
              Corresponds  to the st_rdev field in the struct stat.  This element is only present
              for device files.

       statdata["major"]
              Corresponds to the st_major field in the struct stat.  This element is only present
              for device files.

       statdata["minor"]
              Corresponds to the st_minor field in the struct stat.  This element is only present
              for device files.

       statdata["blksize"]
              Corresponds to the st_blksize field in the struct stat, if this field is present on
              your system.  (It is present on all modern systems that we know of.)

       statdata["pmode"]
              A human-readable version of the mode value, such as printed by ls(1).  For example,
              "-rwxr-xr-x".

       statdata["linkval"]
              If the named file is a symbolic link, this element will exist and its value is  the
              value of the symbolic link (where the symbolic link points to).

       statdata["type"]
              The  type  of  the  file as a string. One of "file", "blockdev", "chardev", "direc‐
              tory", "socket", "fifo", "symlink", "door", or "unknown".  Not all systems  support
              all file types.

   fts()
       The  fts()  function  provides  a  hook  to the fts(3) set of routines for traversing file
       heirarchies.  Instead of returning data about one file at a time in a stream, it fills  in
       a  multi-dimensional  array  with  data  about  each file and directory encountered in the
       requested heirarchies.

       The arguments are as follows:

       pathlist
              An array of filenames.  The element values are used; the index values are ignored.

       flags  This should be the bitwise OR of one or more of the following predefined flag  val‐
              ues.  At least one of FTS_LOGICAL or FTS_PHYSICAL must be provided; otherwise fts()
              returns an error value and sets ERRNO.

              FTS_LOGICAL
                     Do a ``logical'' file traversal, where the information returned for  a  sym‐
                     bolic  link  refers  to  the  linked-to  file,  and not to the symbolic link
                     itself.  This flag is mutually exclusive with FTS_PHYSICAL.

              FTS_PHYSICAL
                     Do a ``physical'' file traversal, where the information returned for a  sym‐
                     bolic link refers to the symbolic link itself.  This flag is mutually exclu‐
                     sive with FTS_LOGICAL.

              FTS_NOCHDIR
                     As a performance optimization, the fts(3) routines change directory as  they
                     traverse a file heirarchy.  This flag disables that optimization.

              FTS_COMFOLLOW
                     Immediatly follow a symbolic link named in pathlist, whether or not FTS_LOG‐
                     ICAL is set.

              FTS_SEEDOT
                     By default, the fts(3) routines do not return entries for ``.'' and  ``..''.
                     This  option causes entries for ``..'' to also be included.  (The AWK exten‐
                     sion always includes an entry for ``.'', see below.)

              FTS_XDEV
                     During a traversal, do not cross onto a different mounted filesystem.

       filedata
              The filedata array is first cleared.  Then, fts() creates an  element  in  filedata
              for  every  element  in  pathlist.   The index is the name of the directory or file
              given in pathlist.  The element for this index is itself an array.  There  are  two
              cases.

              The path is a file.
                     In this case, the array contains two or three elements:

                     "path" The full path to this file, starting from the ``root'' that was given
                            in the pathlist array.

                     "stat" This element is itself an array, containing the same  information  as
                            provided  by  the  stat() function described earlier for its statdata
                            argument.  The element may not be present if  stat(2)  for  the  file
                            failed.

                     "error"
                            If some kind of error was encountered, the array will also contain an
                            element named "error", which is a string describing the error.

              The path is a directory.
                     In this case, the array contains one element for each entry  in  the  direc‐
                     tory.   If an entry is a file, that element is as for files, just described.
                     If the entry is  a  directory,  that  element  is  (recursively),  an  array
                     describing  the subdirectory.  If FTS_SEEDOT was provided in the flags, then
                     there will also be an element named "..".  This element  will  be  an  array
                     containing the data as provided by stat().

                     In  addition,  there will be an element whose index is ".".  This element is
                     an array containing the same two or three elements as for  a  file:  "path",
                     "stat", and "error".

       The fts() function returns 0 if there were no errors. Otherwise it returns -1.

NOTES
       The  AWK  fts()  extension  does  not  exactly mimic the interface of the fts(3) routines,
       choosing instead to provide an interface that is based on associative arrays, which should
       be  more  comfortable  to use from an AWK program.  This includes the lack of a comparison
       function, since gawk  already  provides  powerful  array  sorting  facilities.   While  an
       fts_read()-like  interface  could  have  been provided, this felt less natural than simply
       creating a multi-dimensional array to represent the file heirarchy and its information.

       Nothing prevents AWK code from changing the predefined FTS_xx values, but doing so is  may
       cause strange results when the changed values are passed to fts().

BUGS
       There are many more file-related functions for which AWK interfaces would be desirable.

EXAMPLE
       See test/fts.awk in the gawk distribution for an example.

SEE ALSO
       GAWK: Effective AWK Programming, fnmatch(3am), fork(3am), inplace(3am), ordchr(3am), read‐
       dir(3am), readfile(3am), revoutput(3am), rwarray(3am), time(3am).

       chdir(2), fts(3), stat(2).

AUTHOR
       Arnold Robbins, arnold@skeeve.com.

COPYING PERMISSIONS
       Copyright © 2012, 2013, Free Software Foundation, Inc.

       Permission is granted to make and distribute verbatim copies of this manual page  provided
       the copyright notice and this permission notice are preserved on all copies.

       Permission  is  granted to copy and distribute modified versions of this manual page under
       the conditions for verbatim copying, provided that the entire resulting  derived  work  is
       distributed under the terms of a permission notice identical to this one.

       Permission is granted to copy and distribute translations of this manual page into another
       language, under the above conditions for modified versions, except  that  this  permission
       notice may be stated in a translation approved by the Foundation.

Free Software Foundation                   Jan 15 2013                             FILEFUNCS(3am)

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