file::spec::unix.3

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.\" ========================================================================
.\"
.IX Title "File::Spec::Unix 3"
.TH File::Spec::Unix 3 "2008-01-23" "perl v5.10.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
File::Spec::Unix \- File::Spec for Unix, base for other File::Spec modules
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& require File::Spec::Unix; # Done automatically by File::Spec
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Methods for manipulating file specifications.  Other File::Spec
modules, such as File::Spec::Mac, inherit from File::Spec::Unix and
override specific methods.
.SH "METHODS"
.IX Header "METHODS"
.IP "\fIcanonpath()\fR" 2
.IX Item "canonpath()"
No physical check on the filesystem, but a logical cleanup of a
path. On \s-1UNIX\s0 eliminates successive slashes and successive \*(L"/.\*(R".
.Sp
.Vb 1
\&    $cpath = File::Spec\->canonpath( $path ) ;
.Ve
.Sp
Note that this does *not* collapse \fIx/../y\fR sections into \fIy\fR.  This
is by design.  If \fI/foo\fR on your system is a symlink to \fI/bar/baz\fR,
then \fI/foo/../quux\fR is actually \fI/bar/quux\fR, not \fI/quux\fR as a naive
\&\fI../\fR\-removal would give you.  If you want to do this kind of
processing, you probably want \f(CW\*(C`Cwd\*(C'\fR's \f(CW\*(C`realpath()\*(C'\fR function to
actually traverse the filesystem cleaning up paths like this.
.IP "\fIcatdir()\fR" 2
.IX 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
\&\s-1OS2\s0. Of course, if this is the root directory, don't cut off the
trailing slash :\-)
.IP "catfile" 2
.IX Item "catfile"
Concatenate one or more directory names and a filename to form a
complete path ending with a filename
.IP "curdir" 2
.IX Item "curdir"
Returns a string representation of the current directory.  \*(L".\*(R" on \s-1UNIX\s0.
.IP "devnull" 2
.IX Item "devnull"
Returns a string representation of the null device. \*(L"/dev/null\*(R" on \s-1UNIX\s0.
.IP "rootdir" 2
.IX Item "rootdir"
Returns a string representation of the root directory.  \*(L"/\*(R" on \s-1UNIX\s0.
.IP "tmpdir" 2
.IX Item "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:
.Sp
.Vb 2
\&    $ENV{TMPDIR}
\&    /tmp
.Ve
.Sp
Since perl 5.8.0, if running under taint mode, and if \f(CW$ENV\fR{\s-1TMPDIR\s0}
is tainted, it is not used.
.IP "updir" 2
.IX Item "updir"
Returns a string representation of the parent directory.  \*(L"..\*(R" on \s-1UNIX\s0.
.IP "no_upwards" 2
.IX 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.)
.IP "case_tolerant" 2
.IX Item "case_tolerant"
Returns a true or false value indicating, respectively, that alphabetic
is not or is significant when comparing file specifications.
.IP "file_name_is_absolute" 2
.IX Item "file_name_is_absolute"
Takes as argument a path and returns true if it is an absolute path.
.Sp
This does not consult the local filesystem on Unix, Win32, \s-1OS/2\s0 or Mac 
\&\s-1OS\s0 (Classic).  It does consult the working environment for \s-1VMS\s0 (see
\&\*(L"file_name_is_absolute\*(R" in File::Spec::VMS).
.IP "path" 2
.IX Item "path"
Takes no argument, returns the environment variable \s-1PATH\s0 as an array.
.IP "join" 2
.IX Item "join"
join is the same as catfile.
.IP "splitpath" 2
.IX Item "splitpath"
.Vb 2
\&    ($volume,$directories,$file) = File::Spec\->splitpath( $path );
\&    ($volume,$directories,$file) = File::Spec\->splitpath( $path, $no_file );
.Ve
.Sp
Splits a path into volume, directory, and filename portions. On systems
with no concept of volume, returns '' for volume.
.Sp
For systems with no syntax differentiating filenames from directories, 
assumes that the last file is a path unless \f(CW$no_file\fR is true or a 
trailing separator or /. or /.. is present. On Unix this means that \f(CW$no_file\fR
true makes this return ( '', \f(CW$path\fR, '' ).
.Sp
The directory portion may or may not be returned with a trailing '/'.
.Sp
The results can be passed to \*(L"\fIcatpath()\fR\*(R" to get back a path equivalent to
(usually identical to) the original path.
.IP "splitdir" 2
.IX Item "splitdir"
The opposite of \*(L"\fIcatdir()\fR\*(R".
.Sp
.Vb 1
\&    @dirs = File::Spec\->splitdir( $directories );
.Ve
.Sp
\&\f(CW$directories\fR 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.
.Sp
Unlike just splitting the directories on the separator, empty
directory names (\f(CW\*(Aq\*(Aq\fR) can be returned, because these are significant
on some OSs.
.Sp
On Unix,
.Sp
.Vb 1
\&    File::Spec\->splitdir( "/a/b//c/" );
.Ve
.Sp
Yields:
.Sp
.Vb 1
\&    ( \*(Aq\*(Aq, \*(Aqa\*(Aq, \*(Aqb\*(Aq, \*(Aq\*(Aq, \*(Aqc\*(Aq, \*(Aq\*(Aq )
.Ve
.IP "\fIcatpath()\fR" 2
.IX Item "catpath()"
Takes volume, directory and file portions and returns an entire path. Under
Unix, \f(CW$volume\fR is ignored, and directory and file are concatenated.  A '/' is
inserted if needed (though if the directory portion doesn't start with
\&'/' it is not added).  On other OSs, \f(CW$volume\fR is significant.
.IP "abs2rel" 2
.IX Item "abs2rel"
Takes a destination path and an optional base path returns a relative path
from the base path to the destination path:
.Sp
.Vb 2
\&    $rel_path = File::Spec\->abs2rel( $path ) ;
\&    $rel_path = File::Spec\->abs2rel( $path, $base ) ;
.Ve
.Sp
If \f(CW$base\fR is not present or '', then \fIcwd()\fR is used. If \f(CW$base\fR is
relative, then it is converted to absolute form using
\&\*(L"\fIrel2abs()\fR\*(R". This means that it is taken to be relative to
\&\fIcwd()\fR.
.Sp
On systems that have a grammar that indicates filenames, this ignores the 
\&\f(CW$base\fR filename. Otherwise all path components are assumed to be
directories.
.Sp
If \f(CW$path\fR is relative, it is converted to absolute form using \*(L"\fIrel2abs()\fR\*(R".
This means that it is taken to be relative to \fIcwd()\fR.
.Sp
No checks against the filesystem are made.  On \s-1VMS\s0, there is
interaction with the working environment, as logicals and
macros are expanded.
.Sp
Based on code written by Shigio Yamaguchi.
.IP "\fIrel2abs()\fR" 2
.IX Item "rel2abs()"
Converts a relative path to an absolute path.
.Sp
.Vb 2
\&    $abs_path = File::Spec\->rel2abs( $path ) ;
\&    $abs_path = File::Spec\->rel2abs( $path, $base ) ;
.Ve
.Sp
If \f(CW$base\fR is not present or '', then \fIcwd()\fR is used. If \f(CW$base\fR is
relative, then it is converted to absolute form using
\&\*(L"\fIrel2abs()\fR\*(R". This means that it is taken to be relative to
\&\fIcwd()\fR.
.Sp
On systems that have a grammar that indicates filenames, this ignores
the \f(CW$base\fR filename. Otherwise all path components are assumed to be
directories.
.Sp
If \f(CW$path\fR is absolute, it is cleaned up and returned using \*(L"\fIcanonpath()\fR\*(R".
.Sp
No checks against the filesystem are made.  On \s-1VMS\s0, there is
interaction with the working environment, as logicals and
macros are expanded.
.Sp
Based on code written by Shigio Yamaguchi.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (c) 2004 by the Perl 5 Porters.  All rights reserved.
.PP
This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
File::Spec