source: trunk/essentials/dev-lang/perl/lib/File/Spec.pm@ 3299

package File::Spec;

use strict;
use vars qw(@ISA $VERSION);

$VERSION = '3.12';
$VERSION = eval $VERSION;

my %module = (MacOS   => 'Mac',
              MSWin32 => 'Win32',
              os2     => 'OS2',
              VMS     => 'VMS',
              epoc    => 'Epoc',
              NetWare => 'Win32', # Yes, File::Spec::Win32 works on NetWare.
              symbian => 'Win32', # Yes, File::Spec::Win32 works on symbian.
              dos     => 'OS2',   # Yes, File::Spec::OS2 works on DJGPP.
              cygwin  => 'Cygwin');


my $module = $module{$^O} || 'Unix';

require "File/Spec/$module.pm";
@ISA = ("File::Spec::$module");

1;

__END__

=head1 NAME

File::Spec - portably perform operations on file names

=head1 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');

=head1 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 KE<ouml>nig, 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, L<File::Spec::Functions> provides convenient functional
forms of these methods.

=head1 METHODS

=over 2

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

=item 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 );

=item 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 );

=item curdir

Returns a string representation of the current directory.

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

=item devnull

Returns a string representation of the null device.

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

=item rootdir

Returns a string representation of the root directory.

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

=item 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 C<$ENV{TMPDIR}>
(unless taint is on) and F</tmp>.

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

=item updir

Returns a string representation of the parent directory.

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

=item 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 );

=item 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();

=item 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 L<File::Spec::VMS/file_name_is_absolute>).

=item path

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

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

=item join

join is the same as catfile.

=item 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 C<$no_file> is true or a
trailing separator or F</.> or F</..> is present. On Unix, this means that C<$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 L</catpath()> to get back a path equivalent to
(usually identical to) the original path.

=item splitdir

The opposite of L</catdir()>.

    @dirs = File::Spec->splitdir( $directories );

C<$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 (C<''>) can be returned, because these are significant
on some OSes.

=item catpath()

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

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

=item 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 C<$base> is not present or '', then L<cwd()|Cwd> is used. If C<$base> is
relative, then it is converted to absolute form using
L</rel2abs()>. This means that it is taken to be relative to
L<cwd()|Cwd>.

On systems with the concept of volume, if C<$path> and C<$base> appear to be
on two different volumes, we will not attempt to resolve the two
paths, and we will instead simply return C<$path>.  Note that previous
versions of this module ignored the volume of C<$base>, which resulted in
garbage results part of the time.

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

If C<$path> is relative, it is converted to absolute form using L</rel2abs()>.
This means that it is taken to be relative to L<cwd()|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.

=item rel2abs()

Converts a relative path to an absolute path. 

    $abs_path = File::Spec->rel2abs( $path ) ;
    $abs_path = File::Spec->rel2abs( $path, $base ) ;

If C<$base> is not present or '', then L<cwd()|Cwd> is used. If C<$base> is relative,
then it is converted to absolute form using L</rel2abs()>. This means that it
is taken to be relative to L<cwd()|Cwd>.

On systems with the concept of volume, if C<$path> and C<$base> appear to be
on two different volumes, we will not attempt to resolve the two
paths, and we will instead simply return C<$path>.  Note that previous
versions of this module ignored the volume of C<$base>, which resulted in
garbage results part of the time.

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

If C<$path> is absolute, it is cleaned up and returned using L</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.

=back

For further information, please see L<File::Spec::Unix>,
L<File::Spec::Mac>, L<File::Spec::OS2>, L<File::Spec::Win32>, or
L<File::Spec::VMS>.

=head1 SEE ALSO

L<File::Spec::Unix>, L<File::Spec::Mac>, L<File::Spec::OS2>,
L<File::Spec::Win32>, L<File::Spec::VMS>, L<File::Spec::Functions>,
L<ExtUtils::MakeMaker>

=head1 AUTHOR

Currently maintained by Ken Williams C<< <[email protected]> >>.

The vast majority of the code was written by
Kenneth Albanowski C<< <[email protected]> >>,
Andy Dougherty C<< <[email protected]> >>,
Andreas KE<ouml>nig C<< <[email protected]> >>,
Tim Bunce C<< <[email protected]> >>.
VMS support by Charles Bailey C<< <[email protected]> >>.
OS/2 support by Ilya Zakharevich C<< <[email protected]> >>.
Mac support by Paul Schinder C<< <[email protected]> >>, and
Thomas Wegner C<< <[email protected]> >>.
abs2rel() and rel2abs() written by Shigio Yamaguchi C<< <[email protected]> >>,
modified by Barrie Slaymaker C<< <[email protected]> >>.
splitpath(), splitdir(), catpath() and catdir() by Barrie Slaymaker.

=head1 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.

=cut