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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 facilities.

   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 success-
       ful, 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 ele-
              ment is only present for device files.

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

       statdata["minor"]
              Corresponds to the st_minor field in the struct stat.  This ele-
              ment 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  sym-
              bolic link points to).

       statdata["type"]
              The  type  of  the  file as a string. One of "file", "blockdev",
              "chardev", "directory", "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 hierarchies.  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 hierarchies.

       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  values.   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 symbolic  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 symbolic link refers to the symbolic link
                     itself.  This flag is mutually exclusive  with  FTS_LOGI-
                     CAL.

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

              FTS_COMFOLLOW
                     Immediately  follow  a  symbolic  link named in pathlist,
                     whether or not FTS_LOGICAL 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 extension always  includes
                     an entry for ``.'', see below.)

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

              FTS_SKIP
                     When  set,  causes  top  level  directories  to  not   be
                     descended into.

       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 ele-
              ment 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()  func-
                            tion  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 directory.  If an entry is a file, that ele-
                     ment  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 nat-
       ural  than  simply  creating a multi-dimensional array to represent the
       file hierarchy and its information.

       Nothing prevents AWK code from changing the predefined  FTS_xx  values,
       but  doing  so  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.

       It's not clear why I thought adding FTS_SKIP was a good idea.


EXAMPLE

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


SEE ALSO

       GAWK: Effective AWK Programming, fnmatch(3), fork(3), inplace(3),
       ordchr(3), readdir(3), readfile(3), revoutput(3), rwarray(3),
       time(3).

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


AUTHOR

       Arnold Robbins, arnold@skeeve.com.


COPYING PERMISSIONS

       Copyright (C) 2012, 2013, 2018, 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  man-
       ual page into another language, under the above conditions for modified
       versions, except that this permission notice may be stated in a  trans-
       lation approved by the Foundation.



Free Software Foundation          Feb 21 2018                   FILEFUNCS(3am)

gawk 5.0.0 - Generated Fri Apr 12 12:19:37 CDT 2019
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