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<TITLE>abs2rel - convert an absolute path to a relative path
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<UL>
<LI><A HREF="#NAME">NAME</A>
<LI><A HREF="#SYNOPSIS">SYNOPSIS</A>
<LI><A HREF="#DESCRIPTION">DESCRIPTION</A>
<LI><A HREF="#BUGS">BUGS</A>
<LI><A HREF="#LIMITATIONS">LIMITATIONS</A>
<LI><A HREF="#AUTHORS">AUTHORS</A>
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<P>
<H1><A NAME="NAME">NAME
</A></H1>
abs2rel - convert an absolute path to a relative path
<P>
rel2abs - convert a relative path to an absolute path
<P>
realpath - convert a logical path to a physical path (resolve symlinks)
<P>
splitpath - split a path in to volume, directory and filename components
<P>
joinpath - join volume, directory, and filename components to form a path
<P>
splitdirs - split directory specification in to component names
<P>
joindirs - join component names in to a directory specification
<P>
setfstype - set the file system type
<P>
<P>
<HR>
<H1><A NAME="SYNOPSIS">SYNOPSIS
</A></H1>
<PRE> use <A HREF="File::PathConvert">File::PathConvert</A> qw(realpath abs2rel rel2abs setfstype splitpath
joinpath splitdirs joindirs $resolved);
</PRE>
<P>
<PRE> $relpath = abs2rel($abspath);
$abspath = abs2rel($abspath, $base);
</PRE>
<P>
<PRE> $abspath = rel2abs($relpath);
$abspath = rel2abs($relpath, $base);
</PRE>
<P>
<PRE> $path = realpath($logpath) || die "resolution stopped at $resolved";
</PRE>
<P>
<PRE> ( $volume, $directory, $filename )= splitpath( $path ) ;
( $volume, $directory, $filename )= splitpath( $path, 'nofile' ) ;
</PRE>
<P>
<PRE> $path= joinpath( $volume, $directory, $filename ) ;
</PRE>
<P>
<PRE> @directories= splitdirs( $directory ) ;
$directory= joindirs( @directories ) ;
</PRE>
<P>
<P>
<HR>
<H1><A NAME="DESCRIPTION">DESCRIPTION
</A></H1>
File::PathConvert provides functions to convert between absolute and
relative paths, and from logical paths to physical paths on a variety of
filesystems, including the URL 'filesystem'.
<P>
Paths are decomposed internally in to volume, directory, and, sometimes
filename portions as appropriate to the operation and filesystem, then
recombined. This preserves the volume and filename portions so that they
may be returned, and prevents them from interfering with the path
conversions.
<P>
Here are some examples of path decomposition. A '****' in a column
indicates the column is not used in <A HREF="#item_abs2rel">abs2rel</A> and <A HREF="#item_rel2abs">rel2abs</A> functions for that filesystem type.
<P>
<PRE> FS VOLUME Directory filename
======= ======================= =============== =============
URL http: /a/b/ c?query
<A HREF="http://fubar.com">http://fubar.com</A> /a/b/ c?query
//p.d.q.com /a/b/c/ ?query
</PRE>
<P>
<PRE> VMS Server::Volume: [a.b] c
Server"access spec":: [a.b] c
Volume: [a.b] c
</PRE>
<P>
<PRE> Win32 A: \a\b\c ****
\\server\Volume \a\b\c ****
\\server\Volume \a/b/c ****
</PRE>
<P>
<PRE> Unix **** \a\b\c ****
</PRE>
<P>
<PRE> MacOS Volume:: a:b:c ****
</PRE>
<P>
Many more examples abound in the test.pl included with this module.
<P>
Only the VMS and URL filesystems indicate if the last name in a path is a
directory or file. For other filesystems, all non-volume names are assumed
to be directory names. For URLs, the last name in a path is assumed to be a
filename unless it ends in '/'.
<P>
Other assumptions are made as well, especially MacOS and VMS. THESE MAY
CHANGE BASED ON PROGRAMMER FEEDBACK!
<P>
The conversion routines <A HREF="#item_abs2rel">abs2rel</A>, <A HREF="#item_rel2abs">rel2abs</A>, and <A HREF="#item_realpath">realpath</A> are the main focus of this package. <A HREF="#item_splitpath">splitpath</A> and <A HREF="#item_joinpath">joinpath</A> are provided to allow volume oriented filesystems (almost anything
non-unixian, actually) to be accomodated. <A HREF="#item_splitdirs">splitdirs</A> and <A HREF="#item_joindirs">joindirs</A> provide directory path grammar parsing and encoding, which is especially
useful for VMS.
<P>
<DL>
<DT><STRONG><A NAME="item_setfstype">setfstype
</A></STRONG><DD>
This is called automatically on module load to set the filesystem type
according to $^O. The user can call this later set the filesystem type
manually. If the name is not recognized, unix defaults are used. Names
matching /^URL$/i, /^VMS$/i, /^MacOS$/i, or /^(ms)?(win|dos)/32|nt)?$/i
yield the appropriate (hopefully) filesystem settings. These strings may be
generalized in the future.
<P>
Examples:
<P>
<PRE> <A HREF="File::PathConvert::setfstype">File::PathConvert::setfstype</A>( 'url' ) ;
<A HREF="File::PathConvert::setfstype">File::PathConvert::setfstype</A>( 'Win32' ) ;
<A HREF="File::PathConvert::setfstype">File::PathConvert::setfstype</A>( 'HAL9000' ) ; # Results in Unix default
</PRE>
<P>
<DT><STRONG><A NAME="item_abs2rel">abs2rel
</A></STRONG><DD>
<A HREF="#item_abs2rel">abs2rel</A> converts an absolute path name to a relative path: converting /1/2/3/a/b/c
relative to /1/2/3 returns a/b/c
<P>
<PRE> $relpath= abs2rel( $abspath ) ;
$relpath= abs2rel( $abspath, $base ) ;
</PRE>
<P>
If <CODE>$abspath</CODE> is already relative, it is returned unchanged.
Otherwise the relative path from <CODE>$base</CODE> to
<CODE>$abspath</CODE> is returned. If <CODE>$base</CODE> is undefined the
current directory is used.
<P>
The volume and filename portions of <CODE>$base</CODE> are ignored if
present. If <CODE>$abspath</CODE> and <CODE>$base</CODE> are on different
volumes, the volume from <CODE>$abspath</CODE> is used.
<P>
No filesystem calls are made except for getting the current working
directory if <CODE>$base</CODE> is undefined, so symbolic links are not
checked for or resolved, and no check is done for existance.
<P>
Examples
<P>
<PRE> # Unix
'a/b/c' == abs2rel( 'a/b/c', $anything )
'a/b/c' == abs2rel( '/1/2/3/a/b/c', '/1/2/3' )
</PRE>
<P>
<PRE> # DOS
'a\\b/c' == abs2rel( 'a\\b/c', $anything )
'a\\b/c' == abs2rel( '/1\\2/3/a\\b/c', '/1/2/3' )
</PRE>
<P>
<PRE> # URL
'<A HREF="http:a/b/c">http:a/b/c</A>' == abs2rel( '<A HREF="http:a/b/c">http:a/b/c</A>', $anything )
'<A HREF="http:a/b/c">http:a/b/c</A>' == abs2rel( '<A HREF="http:/1/2/3/a/b/c">http:/1/2/3/a/b/c</A>',
'<A HREF="ftp://t.org/1/2/3/?z">ftp://t.org/1/2/3/?z</A>' )
'<A HREF="http:a/b/c?q">http:a/b/c?q</A>' == abs2rel( '<A HREF="http:/1/2/3/a/b/c/?q">http:/1/2/3/a/b/c/?q</A>',
'<A HREF="ftp://t.org/1/2/3?z">ftp://t.org/1/2/3?z</A>' )
'<A HREF="http://s.com/a/b/c?q">http://s.com/a/b/c?q</A>' == abs2rel( '<A HREF="http://s.com/1/2/3/a/b/c?q">http://s.com/1/2/3/a/b/c?q</A>',
'<A HREF="ftp://t.org/1/2/3/?z">ftp://t.org/1/2/3/?z</A>')
</PRE>
<P>
<DT><STRONG><A NAME="item_rel2abs">rel2abs
</A></STRONG><DD>
<A HREF="#item_rel2abs">rel2abs</A> makes converts a relative path name to an absolute path: converting a/b/c
relative to /1/2/3 returns /1/2/3/a/b/c.
<P>
<PRE> $abspath= rel2abs( $relpath ) ;
$abspath= rel2abs( $relpath, $base ) ;
</PRE>
<P>
If <CODE>$relpath</CODE> is already absolute, it is returned unchanged.
Otherwise <CODE>$relpath</CODE> is taken to be relative to
<CODE>$base</CODE> and the resulting absolute path is returned. If
<CODE>$base</CODE> is not supplied, the current working directory is used.
<P>
The volume portion of <CODE>$relpath</CODE> is ignored. The filename
portion of <CODE>$base</CODE> is also ignored. The volume from
<CODE>$base</CODE> is returned if present. The filename portion of
<CODE>$abspath</CODE> is returned if present.
<P>
No filesystem calls are made except for getting the current working
directory if <CODE>$base</CODE> is undefined, so symbolic links are not
checked for or resolved, and no check is done for existance.
<P>
Examples
<P>
<PRE> # Unix
'/a/b/c' == rel2abs( '/a/b/c', $anything )
'/1/2/3/a/b/c' == rel2abs( 'a/b/c', '/1/2/3' )
</PRE>
<P>
<PRE> # DOS
'\\a\\b/c' == rel2abs( '\\a\\b/c', $anything )
'/1\\2/3\\a\\b/c' == rel2abs( 'a\\b/c', '/1\\2/3' )
'C:/1\\2/3\\a\\b/c' == rel2abs( 'D:a\\b/c', 'C:/1\\2/3' )
'\\\\s\\v/1\\2/3\\a\\b/c' == rel2abs( 'D:a\\b/c', '\\\\s\\v/1\\2/3' )
</PRE>
<P>
<PRE> # URL
'<A HREF="http:/a/b/c?q">http:/a/b/c?q</A>' == rel2abs( '<A HREF="http:/a/b/c?q">http:/a/b/c?q</A>', $anything )
'<A HREF="ftp://t.org/1/2/3/a/b/c?q">ftp://t.org/1/2/3/a/b/c?q</A>'== rel2abs( '<A HREF="http:a/b/c?q">http:a/b/c?q</A>',
'<A HREF="ftp://t.org/1/2/3?z">ftp://t.org/1/2/3?z</A>' )
</PRE>
<P>
<DT><STRONG><A NAME="item_realpath">realpath
</A></STRONG><DD>
<A HREF="#item_realpath">realpath</A> makes a canonicalized absolute pathname and resolves all symbolic links,
extra ``/'' characters, and references to /./ and /../ in the path.
<A HREF="#item_realpath">realpath</A> resolves both absolute and relative paths. It returns the resolved name on
success, otherwise it returns undef and sets the valiable <CODE>$File::PathConvert::resolved</CODE> to the pathname that caused the problem.
<P>
All but the last component of the path must exist.
<P>
This implementation is based on 4.4BSD <CODE>realpath(3).</CODE> It is not
tested under other operating systems at this time.
<P>
If '/sys' is a symbolic link to '/usr/src/sys':
<P>
<PRE> chdir('/usr');
'/usr/src/sys/kern' == realpath('../sys/kern');
'/usr/src/sys/kern' == realpath('/sys/kern');
</PRE>
<P>
<DT><STRONG><A NAME="item_splitpath">splitpath
</A></STRONG><DD>
To be written...
<P>
<DT><STRONG><A NAME="item_joinpath">joinpath
</A></STRONG><DD>
To be written...
<P>
<DT><STRONG><A NAME="item_splitdirs">splitdirs
</A></STRONG><DD>
To be written...
<P>
<DT><STRONG><A NAME="item_joindirs">joindirs
</A></STRONG><DD>
</DL>
<P>
<HR>
<H1><A NAME="BUGS">BUGS
</A></H1>
<A HREF="#item_realpath">realpath</A> is not fully multiplatform.
<P>
<P>
<HR>
<H1><A NAME="LIMITATIONS">LIMITATIONS
</A></H1>
<UL>
<LI><STRONG></STRONG>
In URLs, paths not ending in '/' are split such that the last name in the
path is a filename. This is not intuitive: many people use such URLs for
directories, and most servers send a redirect. This may cause programers
using this package to code in bugs, it may be more pragmatic to always
assume all names are directory names. (Note that the query portion is
always part of the filename).
<P>
<LI><STRONG></STRONG>
If the relative and base paths are on different volumes, no error is
returned. A silent, hopefully reasonable assumption is made.
<P>
<LI><STRONG></STRONG>
No detection of unix style paths is done when other filesystems are
selected, like File::Basename does.
<P>
</UL>
<P>
<HR>
<H1><A NAME="AUTHORS">AUTHORS
</A></H1>
Barrie Slaymaker <A HREF="MAILTO:<rbs@telerama.com>"><rbs@telerama.com></A>
Shigio Yamaguchi <A
HREF="MAILTO:<shigio@wafu.netgate.net>"><shigio@wafu.netgate.net></A>
<P>
</DL>
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