File::Spec::Mac(3Perl Programmers Reference GuFile::Spec::Mac(3p)NAMEFile::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. Result-
ing 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 abso-
lute. 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 con-
vention 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 con-
catenate paths instead of directory names (strictly speak-
ing, 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 argu-
ments 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 argu-
ment, 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
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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 coun-
terparts:
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. How-
ever, 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, direc-
tory 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
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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 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 abso-
lute. 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 exist-
ing scripts.
The last argument is always considered to be the file por-
tion. 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
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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 direc-
tory 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 rela-
tive 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 dis-
tinguish unambiguously. As a special case, the filename ''
is always considered to be absolute. Note that with ver-
sion 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)
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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 por-
tions.
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 direc-
tories. Consider using "splitpath()" otherwise.
Unlike just splitting the directories on the separator,
empty directory names ("") can be returned. Since "cat-
dir()" on Mac OS always appends a trailing colon to dis-
tinguish 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:
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( "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 relative path from the base path to the destina-
tion 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 con-
verted to absolute form using "rel2abs()". This means that
it is taken to be relative to the current working direc-
tory.
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.
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If $path is relative, it is converted to absolute form
using "rel2abs()". This means that it is taken to be rela-
tive to the current 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
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 work-
ing 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 implementation of these methods, not the semantics.
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