filefuncs

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 de-
                     scended into.

       filedata
              The filedata array is first cleared.  Then, fts() creates an el-
              ement  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 en-
                     try  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 de-
                     scribing 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 pro-
                     vided 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 re-
       turns -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(3am), fork(3am), inplace(3am),
       ordchr(3am), readdir(3am), readfile(3am), revoutput(3am), rwarray(3am),
       time(3am).

       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
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       lation approved by the Foundation.

Free Software Foundation          Feb 21 2018                   FILEFUNCS(3am)