# phpman > man > File::Spec::Unix

## NAME
    [File::Spec::Unix](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec%3A%3AUnix/markdown) - [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown) for Unix, base for other [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown) modules

## SYNOPSIS
     require [File::Spec::Unix](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec%3A%3AUnix/markdown); # Done automatically by [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)

## DESCRIPTION
    Methods for manipulating file specifications. Other [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown) modules, such as [File::Spec::Mac](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec%3A%3AMac/markdown),
    inherit from [File::Spec::Unix](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec%3A%3AUnix/markdown) and override specific methods.

## METHODS
### canonpath
      No physical check on the filesystem, but a logical cleanup of a path. On UNIX eliminates
      successive slashes and successive "/.".

          $cpath = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->canonpath( $path ) ;

      Note that this does *not* collapse x/../y sections into y. This is by design. If /foo on your
      system is a symlink to /bar/baz, then /foo/../quux is actually /bar/quux, not /quux as a naive
      ../-removal would give you. If you want to do this kind of processing, you probably want
      "Cwd"'s "realpath()" function to actually traverse the filesystem cleaning up paths like this.

### catdir
      Concatenate two or more directory names to form a complete path ending with a directory. But
      remove the trailing slash from the resulting string, because it doesn't look good, isn't
      necessary and confuses OS2. Of course, if this is the root directory, don't cut off the
      trailing slash :-)

    catfile
      Concatenate one or more directory names and a filename to form a complete path ending with a
      filename

    curdir
      Returns a string representation of the current directory. "." on UNIX.

    devnull
      Returns a string representation of the null device. "/dev/null" on UNIX.

    rootdir
      Returns a string representation of the root directory. "/" on UNIX.

    tmpdir
      Returns a string representation of the first writable directory from the following list or the
      current directory if none from the list are writable:

          $ENV{TMPDIR}
          /tmp

      If running under taint mode, and if $ENV{TMPDIR} is tainted, it is not used.

    updir
      Returns a string representation of the parent directory. ".." on UNIX.

    no_upwards
      Given a list of file names, strip out those that refer to a parent directory. (Does not strip
      symlinks, only '.', '..', and equivalents.)

    case_tolerant
      Returns a true or false value indicating, respectively, that alphabetic is not or is
      significant when comparing file specifications.

    file_name_is_absolute
      Takes as argument a path and returns true if it is an absolute path.

      This does not consult the local filesystem on Unix, Win32, OS/2 or Mac OS (Classic). It does
      consult the working environment for VMS (see "file_name_is_absolute" in [File::Spec::VMS](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec%3A%3AVMS/markdown)).

    path
      Takes no argument, returns the environment variable PATH as an array.

    join
      join is the same as catfile.

    splitpath
          ($volume,$directories,$file) = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->splitpath( $path );
          ($volume,$directories,$file) = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->splitpath( $path,
                                                                $no_file );

      Splits a path into volume, directory, and filename portions. On systems with no concept of
      volume, returns '' for volume.

      For systems with no syntax differentiating filenames from directories, assumes that the last
      file is a path unless $no_file is true or a trailing separator or /. or /.. is present. On
      Unix this means that $no_file true makes this return ( '', $path, '' ).

      The directory portion may or may not be returned with a trailing '/'.

      The results can be passed to "catpath()" to get back a path equivalent to (usually identical
      to) the original path.

    splitdir
      The opposite of "catdir()".

          @dirs = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->splitdir( $directories );

      $directories must be only the directory portion of the path on systems that have the concept
      of a volume or that have path syntax that differentiates files from directories.

      Unlike just splitting the directories on the separator, empty directory names ('') can be
      returned, because these are significant on some OSs.

      On Unix,

          [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->splitdir( "/a/b//c/" );

      Yields:

          ( '', 'a', 'b', '', 'c', '' )

### catpath
      Takes volume, directory and file portions and returns an entire path. Under Unix, $volume is
      ignored, and directory and file are concatenated. A '/' is inserted if needed (though if the
      directory portion doesn't start with '/' it is not added). On other OSs, $volume is
      significant.

    abs2rel
      Takes a destination path and an optional base path returns a relative path from the base path
      to the destination path:

          $rel_path = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->abs2rel( $path ) ;
          $rel_path = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->abs2rel( $path, $base ) ;

      If $base is not present or '', then cwd() is used. If $base is relative, then it is converted
      to absolute form using "rel2abs()". This means that it is taken to be relative to cwd().

      On systems that have a grammar that indicates filenames, this ignores the $base filename.
      Otherwise all path components are assumed to be directories.

      If $path is relative, it is converted to absolute form using "rel2abs()". This means that it
      is taken to be relative to cwd().

      No checks against the filesystem are made, so the result may not be correct if $base contains
      symbolic links. (Apply [Cwd::abs_path](https://www.chedong.com/phpMan.php/perldoc/Cwd%3A%3Aabspath/markdown)() beforehand if that is a concern.) On VMS, there is
      interaction with the working environment, as logicals and macros are expanded.

      Based on code written by Shigio Yamaguchi.

### rel2abs
      Converts a relative path to an absolute path.

          $abs_path = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->rel2abs( $path ) ;
          $abs_path = [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)->rel2abs( $path, $base ) ;

      If $base is not present or '', then cwd() is used. If $base is relative, then it is converted
      to absolute form using "rel2abs()". This means that it is taken to be relative to cwd().

      On systems that have a grammar that indicates filenames, this ignores the $base filename.
      Otherwise all path components are assumed to be directories.

      If $path is absolute, it is cleaned up and returned using "canonpath()".

      No checks against the filesystem are made. On VMS, there is interaction with the working
      environment, as logicals and macros are expanded.

      Based on code written by Shigio Yamaguchi.

## COPYRIGHT
    Copyright (c) 2004 by the Perl 5 Porters. All rights reserved.

    This program is free software; you can redistribute it and/or modify it under the same terms as
    Perl itself.

    Please submit bug reports and patches to <perlbug@perl.org>.

## SEE ALSO
    [File::Spec](https://www.chedong.com/phpMan.php/perldoc/File%3A%3ASpec/markdown)