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RedHat 9 (Linux i386) - man page for file::spec::mac (redhat section 3pm)

File::Spec::Mac(3pm)		 Perl Programmers Reference Guide	     File::Spec::Mac(3pm)

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 abso-
	 lute (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 distin-
	 guish a file path from a directory path.

	 IMPORTANT NOTE: Beginning with version 1.3 of this module, the resulting path is rela-
	 tive by default and not absolute. This descision 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

	     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 denot-
	   ing 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 pat-
	   tern /^[^:]+:/, the resulting path is absolute.

	 7.
	   Passing an empty string "" as the first argument to "catdir()" is like pass-
	   ing"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 immedi-
	   ately followed by updirs. This is invalid, because this would go beyond "root". Gener-
	   ally, 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 compati-
	 bility. 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.

	     $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 abso-
	 lute (but avoid this).

	 IMPORTANT NOTE: Beginning with version 1.3 of this module, the resulting path is rela-
	 tive by default and not absolute. This descision 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 "Macin-
	 toshHD: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 meaning-
	 less 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 in to 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 iden-
	 tical 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:

	     ( "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, $vol-
	 ume, $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.

	 Since Mac OS has the concept of volumes, this assumes that both paths are on the $desti-
	 nation volume, and ignores the $base volume (!).

	 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:

	     $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 <schinder@pobox.com>
       and Thomas Wegner <wegner_thomas@yahoo.com>.

SEE ALSO
       File::Spec

perl v5.8.0				    2002-06-01			     File::Spec::Mac(3pm)


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