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File::Spec

Section: Perl Programmers Reference Guide (3pm)
Updated: 2001-09-21
Index

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 filespecifications (usually called ``file names'', but not to be confused with thecontents of a file, or Perl's file handles), such as concatenating severaldirectory and file names into a single path, or determining whether a pathis rooted. It is based on code directly taken from MakeMaker 5.17, codewritten by Andreas Ko.nig, Andy Dougherty, Charles Bailey, IlyaZakharevich, Paul Schinder, and others.

Since these functions are different for most operating systems, each set ofOS 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 byFile::Spec. Since some modules (like VMS) make use of facilities availableonly under that OS, it may not be possible to load all modules under alloperating 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, File::Spec::Functions provides convenient functionalforms of these methods.

METHODS

canonpath

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

    $cpath = File::Spec->canonpath( $path ) ;

Note that this does *not* collapse x/../y sections into y. Thisis 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 ofprocessing, you probably want "Cwd"'s "realpath()" function toactually traverse the filesystem cleaning up paths like this.

catdir

Concatenate two or more directory names to form a complete path endingwith a directory. But remove the trailing slash from the resultingstring, because it doesn't look good, isn't necessary and confusesOS/2. Of course, if this is the root directory, don't cut off thetrailing slash :-)

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

catfile

Concatenate one or more directory names and a filename to form acomplete 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 alist of possible temporary directories. Returns the current directoryif no writable temporary directories are found. The list of directorieschecked 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 parentdirectory. (Does not strip symlinks, only '.', '..', and equivalents.)

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

case_tolerant

Returns a true or false value indicating, respectively, that alphabeticcase 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, orMac OS (Classic). It does consult the working environment for VMS(see ``file_name_is_absolute'' in File::Spec::VMS).

path

Takes no argument. Returns the environment variable "PATH" (or the localplatform'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 systemswith 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 atrailing separator or /. or /.. is present. On Unix, this means that $no_filetrue 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 differentiatesfiles from directories.

Unlike just splitting the directories on the separator, emptydirectory names ('') can be returned, because these are significanton some OSes.

catpath()

Takes volume, directory and file portions and returns an entire path. UnderUnix, $volume is ignored, and directory and file are concatenated. A '/' isinserted 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 pathfrom 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 isrelative, then it is converted to absolute form using``rel2abs()''. This means that it is taken to be relative tocwd().

On systems with the concept of volume, if $path and $base appear to beon two different volumes, we will not attempt to resolve the twopaths, and we will instead simply return $path. Note that previousversions of this module ignored the volume of $base, which resulted ingarbage 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 bedirectories.

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 isinteraction with the working environment, as logicals andmacros 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 itis taken to be relative to cwd().

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

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

No checks against the filesystem are made. On VMS, there isinteraction with the working environment, as logicals andmacros are expanded.

Based on code written by Shigio Yamaguchi.

For further information, please see File::Spec::Unix,File::Spec::Mac, File::Spec::OS2, File::Spec::Win32, orFile::Spec::VMS.

AUTHOR

Currently maintained by Ken Williams "<KWILLIAMSAATTcpan.org>".

The vast majority of the code was written byKenneth Albanowski "<kjahdsAATTkjahds.com>",Andy Dougherty "<dougheraAATTlafayette.edu>",Andreas Ko.nig "<A.KoenigAATTfranz.ww.TU-Berlin.DE>",Tim Bunce "<Tim.BunceAATTig.co.uk>".VMS support by Charles Bailey "<baileyAATTnewman.upenn.edu>".OS/2 support by Ilya Zakharevich "<ilyaAATTmath.ohio-state.edu>".Mac support by Paul Schinder "<schinderAATTpobox.com>", andThomas Wegner "<wegner_thomasAATTyahoo.com>".abs2rel() and rel2abs() written by Shigio Yamaguchi "<shigioAATTtamacom.com>",modified by Barrie Slaymaker "<barriesAATTslaysys.com>".splitpath(), splitdir(), catpath() and catdir() by Barrie Slaymaker.

COPYRIGHT

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

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