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man : File::Spec::Mac(3p)
File::Spec::Mac(3Perl Programmers Reference GuFile::Spec::Mac(3p)
NAME
File::Spec::Mac - File::Spec for Mac OS (Classic)
SYNOPSIS
require File::Spec::Mac; # Done internally by File::Spec if needed
DESCRIPTION
Methods for manipulating file specifications.
METHODS
canonpath
On Mac OS, there's nothing to be done. Returns what it's
given.
catdir()
Concatenate two or more directory names to form a path
separated by colons (":") ending with a directory.
Resulting paths are relative by default, but can be
forced to be absolute (but avoid this, see below).
Automatically puts a trailing ":" on the end of the
complete path, because that's what's done in MacPerl's
environment and helps to distinguish a file path from a
directory path.
IMPORTANT NOTE: Beginning with version 1.3 of this
module, the resulting path is relative by default and
not absolute. This decision was made due to portability
reasons. Since "File::Spec->catdir()" returns relative
paths on all other operating systems, it will now also
follow this convention on Mac OS. Note that this may
break some existing scripts.
The intended purpose of this routine is to concatenate
directory names. But because of the nature of Macintosh
paths, some additional possibilities are allowed to make
using this routine give reasonable results for some
common situations. In other words, you are also allowed
to concatenate paths instead of directory names
(strictly speaking, a string like ":a" is a path, but
not a name, since it contains a punctuation character
":").
So, beside calls like
catdir("a") = ":a:"
catdir("a","b") = ":a:b:"
catdir() = "" (special case)
calls like the following
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catdir(":a:") = ":a:"
catdir(":a","b") = ":a:b:"
catdir(":a:","b") = ":a:b:"
catdir(":a:",":b:") = ":a:b:"
catdir(":") = ":"
are allowed.
Here are the rules that are used in "catdir()"; note
that we try to be as compatible as possible to Unix:
1.
The resulting path is relative by default, i.e. the
resulting path will have a leading colon.
2.
A trailing colon is added automatically to the
resulting path, to denote a directory.
3.
Generally, each argument has one leading ":" and one
trailing ":" removed (if any). They are then joined
together by a ":". Special treatment applies for
arguments denoting updir paths like "::lib:", see (4),
or arguments consisting solely of colons ("colon
paths"), see (5).
4.
When an updir path like ":::lib::" is passed as
argument, the number of directories to climb up is
handled correctly, not removing leading or trailing
colons when necessary. E.g.
catdir(":::a","::b","c") = ":::a::b:c:"
catdir(":::a::","::b","c") = ":::a:::b:c:"
5.
Adding a colon ":" or empty string "" to a path at any
position doesn't alter the path, i.e. these arguments
are ignored. (When a "" is passed as the first
argument, it has a special meaning, see (6)). This
way, a colon ":" is handled like a "." (curdir) on
Unix, while an empty string "" is generally ignored
(see "Unix->canonpath()" ). Likewise, a "::" is
handled like a ".." (updir), and a ":::" is handled
like a "../.." etc. E.g.
catdir("a",":",":","b") = ":a:b:"
catdir("a",":","::",":b") = ":a::b:"
6.
If the first argument is an empty string "" or is a
volume name, i.e. matches the pattern /^[^:]+:/, the
resulting path is absolute.
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7.
Passing an empty string "" as the first argument to
"catdir()" is like passing"File::Spec->rootdir()" as
the first argument, i.e.
catdir("","a","b") is the same as
catdir(rootdir(),"a","b").
This is true on Unix, where "catdir("","a","b")"
yields "/a/b" and "rootdir()" is "/". Note that
"rootdir()" on Mac OS is the startup volume, which is
the closest in concept to Unix' "/". This should help
to run existing scripts originally written for Unix.
8.
For absolute paths, some cleanup is done, to ensure
that the volume name isn't immediately followed by
updirs. This is invalid, because this would go beyond
"root". Generally, these cases are handled like their
Unix counterparts:
Unix:
Unix->catdir("","") = "/"
Unix->catdir("",".") = "/"
Unix->catdir("","..") = "/" # can't go beyond root
Unix->catdir("",".","..","..","a") = "/a"
Mac:
Mac->catdir("","") = rootdir() # (e.g. "HD:")
Mac->catdir("",":") = rootdir()
Mac->catdir("","::") = rootdir() # can't go beyond root
Mac->catdir("",":","::","::","a") = rootdir() . "a:" # (e.g. "HD:a:")
However, this approach is limited to the first
arguments following "root" (again, see
"Unix->canonpath()" ). If there are more arguments
that move up the directory tree, an invalid path going
beyond root can be created.
As you've seen, you can force "catdir()" to create an
absolute path by passing either an empty string or a
path that begins with a volume name as the first
argument. However, you are strongly encouraged not to do
so, since this is done only for backward compatibility.
Newer versions of File::Spec come with a method called
"catpath()" (see below), that is designed to offer a
portable solution for the creation of absolute paths.
It takes volume, directory and file portions and returns
an entire path. While "catdir()" is still suitable for
the concatenation of directory names, you are encouraged
to use "catpath()" to concatenate volume names and
directory paths. E.g.
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$dir = File::Spec->catdir("tmp","sources");
$abs_path = File::Spec->catpath("MacintoshHD:", $dir,"");
yields
"MacintoshHD:tmp:sources:" .
catfile
Concatenate one or more directory names and a filename
to form a complete path ending with a filename.
Resulting paths are relative by default, but can be
forced to be absolute (but avoid this).
IMPORTANT NOTE: Beginning with version 1.3 of this
module, the resulting path is relative by default and
not absolute. This decision was made due to portability
reasons. Since "File::Spec->catfile()" returns relative
paths on all other operating systems, it will now also
follow this convention on Mac OS. Note that this may
break some existing scripts.
The last argument is always considered to be the file
portion. Since "catfile()" uses "catdir()" (see above)
for the concatenation of the directory portions (if
any), the following with regard to relative and absolute
paths is true:
catfile("") = ""
catfile("file") = "file"
but
catfile("","") = rootdir() # (e.g. "HD:")
catfile("","file") = rootdir() . file # (e.g. "HD:file")
catfile("HD:","file") = "HD:file"
This means that "catdir()" is called only when there are
two or more arguments, as one might expect.
Note that the leading ":" is removed from the filename,
so that
catfile("a","b","file") = ":a:b:file" and
catfile("a","b",":file") = ":a:b:file"
give the same answer.
To concatenate volume names, directory paths and
filenames, you are encouraged to use "catpath()" (see
below).
curdir
Returns a string representing the current directory. On
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Mac OS, this is ":".
devnull
Returns a string representing the null device. On Mac
OS, this is "Dev:Null".
rootdir
Returns a string representing the root directory. Under
MacPerl, returns the name of the startup volume, since
that's the closest in concept, although other volumes
aren't rooted there. The name has a trailing ":",
because that's the correct specification for a volume
name on Mac OS.
If Mac::Files could not be loaded, the empty string is
returned.
tmpdir
Returns the contents of $ENV{TMPDIR}, if that directory
exits or the current working directory otherwise. Under
MacPerl, $ENV{TMPDIR} will contain a path like
"MacintoshHD:Temporary Items:", which is a hidden
directory on your startup volume.
updir
Returns a string representing the parent directory. On
Mac OS, this is "::".
file_name_is_absolute
Takes as argument a path and returns true, if it is an
absolute path. If the path has a leading ":", it's a
relative path. Otherwise, it's an absolute path, unless
the path doesn't contain any colons, i.e. it's a name
like "a". In this particular case, the path is
considered to be relative (i.e. it is considered to be a
filename). Use ":" in the appropriate place in the path
if you want to distinguish unambiguously. As a special
case, the filename '' is always considered to be
absolute. Note that with version 1.2 of File::Spec::Mac,
this does no longer consult the local filesystem.
E.g.
File::Spec->file_name_is_absolute("a"); # false (relative)
File::Spec->file_name_is_absolute(":a:b:"); # false (relative)
File::Spec->file_name_is_absolute("MacintoshHD:"); # true (absolute)
File::Spec->file_name_is_absolute(""); # true (absolute)
path
Returns the null list for the MacPerl application, since
the concept is usually meaningless under Mac OS. But if
you're using the MacPerl tool under MPW, it gives back
$ENV{Commands} suitably split, as is done in
:lib:ExtUtils:MM_Mac.pm.
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splitpath
($volume,$directories,$file) = File::Spec->splitpath( $path );
($volume,$directories,$file) = File::Spec->splitpath( $path, $no_file );
Splits a path into volume, directory, and filename
portions.
On Mac OS, assumes that the last part of the path is a
filename unless $no_file is true or a trailing separator
":" is present.
The volume portion is always returned with a trailing
":". The directory portion is always returned with a
leading (to denote a relative path) and a trailing ":"
(to denote a directory). The file portion is always
returned without a leading ":". Empty portions are
returned as empty string ''.
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 should 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. Consider using "splitpath()" otherwise.
Unlike just splitting the directories on the separator,
empty directory names ("") can be returned. Since
"catdir()" on Mac OS always appends a trailing colon to
distinguish a directory path from a file path, a single
trailing colon will be ignored, i.e. there's no empty
directory name after it.
Hence, on Mac OS, both
File::Spec->splitdir( ":a:b::c:" ); and
File::Spec->splitdir( ":a:b::c" );
yield:
( "a", "b", "::", "c")
while
File::Spec->splitdir( ":a:b::c::" );
yields:
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( "a", "b", "::", "c", "::")
catpath
$path = File::Spec->catpath($volume,$directory,$file);
Takes volume, directory and file portions and returns an
entire path. On Mac OS, $volume, $directory and $file
are concatenated. A ':' is inserted if need be. You may
pass an empty string for each portion. If all portions
are empty, the empty string is returned. If $volume is
empty, the result will be a relative path, beginning
with a ':'. If $volume and $directory are empty, a
leading ":" (if any) is removed form $file and the
remainder is returned. If $file is empty, the resulting
path will have a trailing ':'.
abs2rel
Takes a destination path and an optional base path and
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 ) ;
Note that both paths are assumed to have a notation that
distinguishes a directory path (with trailing ':') from
a file path (without trailing ':').
If $base is not present or '', then the current working
directory 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 the current
working directory.
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.
If $base doesn't have a trailing colon, the last element
of $base is assumed to be a filename. This filename is
ignored. Otherwise all path components are assumed to
be directories.
If $path is relative, it is converted to absolute form
using "rel2abs()". This means that it is taken to be
relative to the current working directory.
Based on code written by Shigio Yamaguchi.
rel2abs
Converts a relative path to an absolute path:
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$abs_path = File::Spec->rel2abs( $path ) ;
$abs_path = File::Spec->rel2abs( $path, $base ) ;
Note that both paths are assumed to have a notation that
distinguishes a directory path (with trailing ':') from
a file path (without trailing ':').
If $base is not present or '', then $base is set to the
current working directory. If $base is relative, then it
is converted to absolute form using "rel2abs()". This
means that it is taken to be relative to the current
working directory.
If $base doesn't have a trailing colon, the last element
of $base is assumed to be a filename. This filename is
ignored. Otherwise all path components are assumed to
be directories.
If $path is already absolute, it is returned and $base
is ignored.
Based on code written by Shigio Yamaguchi.
AUTHORS
See the authors list in File::Spec. Mac OS support by Paul
Schinder <schinderATpobox.com> and Thomas Wegner
<wegner_thomasATyahoo.com>.
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.
SEE ALSO
See File::Spec and File::Spec::Unix. This package
overrides the implementation of these methods, not the
semantics.
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