File::Spec - portably perform operations on file names

- NAME
- SYNOPSIS
- DESCRIPTION
- METHODS
- SEE ALSO
- AUTHOR
- COPYRIGHT

# NAME

File::Spec - portably perform operations on file names

# SYNOPSIS

            use File::Spec;

            $x=File::Spec->catfile('a', 'b', 'c');

which returns 'a/b/c' under Unix. Or:

            use File::Spec::Functions;

            $x = catfile('a', 'b', 'c');

# DESCRIPTION

This module is designed to support operations commonly performed on file specifications (usually called ``file names'', but not to be confused with the contents of a file, or Perl's file handles), such as concatenating several directory and file names into a single path, or determining whether a path is rooted. It is based on code directly taken from MakeMaker 5.17, code written by Andreas König, Andy Dougherty, Charles Bailey, Ilya Zakharevich, Paul Schinder, and others.

Since these functions are different for most operating systems, each set of OS specific routines is available in a separate module, including:

            File::Spec::Unix
            File::Spec::Mac
            File::Spec::OS2
            File::Spec::Win32
            File::Spec::VMS

The module appropriate for the current OS is automatically loaded by File::Spec. Since some modules (like VMS) make use of facilities available only under that OS, it may not be possible to load all modules under all operating systems.

Since File::Spec is object oriented, subroutines should not be called directly, as in:

            File::Spec::catfile('a','b');

but rather as class methods:

            File::Spec->catfile('a','b');

For simple uses, the File::Spec::Functions manpage provides convenient functional forms of these methods.

# METHODS

canonpath

  No physical check on the filesystem, but a logical cleanup of a path.

          $cpath = File::Spec->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 OS/2. Of course, if this is the root directory, don't cut off the trailing slash :-)

          $path = File::Spec->catdir( @directories );

catfile

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

          $path = File::Spec->catfile( @directories, $filename );

curdir

  Returns a string representation of the current directory.

          $curdir = File::Spec->curdir();

devnull

  Returns a string representation of the null device.

          $devnull = File::Spec->devnull();

rootdir

  Returns a string representation of the root directory.

          $rootdir = File::Spec->rootdir();

tmpdir

  Returns a string representation of the first writable directory from a list of possible temporary directories. Returns the current directory if no writable temporary directories are found. The list of directories checked depends on the platform; e.g. File::Spec::Unix checks `$ENV{TMPDIR}` (unless taint is on) and /tmp.

          $tmpdir = File::Spec->tmpdir();

updir

  Returns a string representation of the parent directory.

          $updir = File::Spec->updir();

no_upwards

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

          @paths = File::Spec->no_upwards( @paths );

case_tolerant

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

          $is_case_tolerant = File::Spec->case_tolerant();

file_name_is_absolute

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

          $is_absolute = File::Spec->file_name_is_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 the File::Spec::VMS manpage).

path

  Takes no argument. Returns the environment variable `PATH` (or the local platform's equivalent) as a list.

          @PATH = File::Spec->path();

join

  join is the same as catfile.

splitpath

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

          ($volume,$directories,$file) = File::Spec->splitpath( $path );
          ($volume,$directories,$file) = File::Spec->splitpath( $path, $no_file );

  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->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 OSes.

`catpath()`

  Takes volume, directory and file portions and returns an entire path. Under Unix, `$volume` is ignored, and directory and file are concatenated. A '/' is inserted if need be. On other OSes, `$volume` is significant.

          $full_path = File::Spec->catpath( $volume, $directory, $file );

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->abs2rel( $path ) ;
          $rel_path = File::Spec->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 with the concept of volume, if `$path` and `$base` appear to be on two different volumes, we will not attempt to resolve the two paths, and we will instead simply return `$path`. Note that previous versions of this module ignored the volume of `$base`, which resulted in garbage results part of the time.

  On systems that have a grammar that indicates filenames, this ignores the `$base` filename as well. 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. 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->rel2abs( $path ) ;
          $abs_path = File::Spec->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 with the concept of volume, if `$path` and `$base` appear to be on two different volumes, we will not attempt to resolve the two paths, and we will instead simply return `$path`. Note that previous versions of this module ignored the volume of `$base`, which resulted in garbage results part of the time.

  On systems that have a grammar that indicates filenames, this ignores the `$base` filename as well. 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.

For further information, please see the File::Spec::Unix manpage, the File::Spec::Mac manpage, the File::Spec::OS2 manpage, the File::Spec::Win32 manpage, or the File::Spec::VMS manpage.

# SEE ALSO

the File::Spec::Unix manpage, the File::Spec::Mac manpage, the File::Spec::OS2 manpage, the File::Spec::Win32 manpage, the File::Spec::VMS manpage, the File::Spec::Functions manpage, the ExtUtils::MakeMaker manpage

# AUTHOR

Currently maintained by Ken Williams `<KWILLIAMS@cpan.org>`.

The vast majority of the code was written by Kenneth Albanowski `<kjahds@kjahds.com>`, Andy Dougherty `<doughera@lafayette.edu>`, Andreas König `<A.Koenig@franz.ww.TU-Berlin.DE>`, Tim Bunce `<Tim.Bunce@ig.co.uk>`. VMS support by Charles Bailey `<bailey@newman.upenn.edu>`. OS/2 support by Ilya Zakharevich `<ilya@math.ohio-state.edu>`. Mac support by Paul Schinder `<schinder@pobox.com>`, and Thomas Wegner `<wegner_thomas@yahoo.com>`. `abs2rel()` and `rel2abs()` written by Shigio Yamaguchi `<shigio@tamacom.com>`, modified by Barrie Slaymaker `<barries@slaysys.com>`. splitpath(), splitdir(), `catpath()` and `catdir()` by Barrie Slaymaker.

# 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.

File::Spec - portably perform operations on file names