File::Spec::Mac
File::Spec::Mac(3) User Contributed Perl Documentation File::Spec::Mac(3)
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 con-
tains a punctuation character ":").
So, beside calls like
catdir("a") = ":a:"
catdir("a","b") = ":a:b:"
catdir() = "" (special case)
calls like the following
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 num-
ber 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->canon-
path()" ). 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.
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 argu-
ments 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 cre-
ation of absolute paths. It takes volume, directory and file por-
tions 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.
$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 com-
plete 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 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 unam-
biguously. 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 $ENV{Commands} suitably split, as is
done in :lib:ExtUtils:MM_Mac.pm.
splitpath
($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 direc-
tory 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 equiva-
lent 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 sys-
tems 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 direc-
tory 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:
( "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 rel-
ative 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 distin-
guishes a directory path (with trailing ':') from a file path (with-
out 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 cur-
rent working directory.
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 ) ;
Note that both paths are assumed to have a notation that distin-
guishes a directory path (with trailing ':') from a file path (with-
out trailing ':').
If $base is not present or '', then $base is set to the current work-
ing 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
<schinder@pobox.com> and Thomas Wegner <wegner_thomas@yahoo.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 imple-
mentation of these methods, not the semantics.
perl v5.8.6 2007-05-21 File::Spec::Mac(3)
