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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)