6 Cwd - get pathname of current working directory
26 use Cwd 'abs_path'; # aka realpath()
27 print abs_path($ENV{'PWD'});
29 use Cwd 'fast_abs_path';
30 print fast_abs_path($ENV{'PWD'});
34 This module provides functions for determining the pathname of the
35 current working directory. By default, it exports the functions
36 cwd(), getcwd(), fastcwd(), and fastgetcwd() into the caller's
37 namespace. Each of these functions are called without arguments and
38 return the absolute path of the current working directory. It is
39 recommended that cwd (or another *cwd() function) be used in I<all>
40 code to ensure portability.
42 The cwd() is the most natural and safe form for the current
43 architecture. For most systems it is identical to `pwd` (but without
44 the trailing line terminator).
46 The getcwd() function re-implements the getcwd(3) (or getwd(3)) functions
49 The fastcwd() function looks the same as getcwd(), but runs faster.
50 It's also more dangerous because it might conceivably chdir() you out
51 of a directory that it can't chdir() you back into. If fastcwd
52 encounters a problem it will return undef but will probably leave you
53 in a different directory. For a measure of extra security, if
54 everything appears to have worked, the fastcwd() function will check
55 that it leaves you in the same directory that it started in. If it has
56 changed it will C<die> with the message "Unstable directory path,
57 current directory changed unexpectedly". That should never happen.
59 The fastgetcwd() function is provided as a synonym for cwd().
61 The abs_path() function takes a single argument and returns the
62 absolute pathname for that argument. It uses the same algorithm as
63 getcwd(). (Actually, getcwd() is abs_path(".")) Symbolic links and
64 relative-path components ("." and "..") are resolved to return the
65 canonical pathname, just like realpath(3). This function is also
66 callable as realpath().
68 The fast_abs_path() function looks the same as abs_path() but runs
69 faster and, like fastcwd(), is more dangerous.
71 If you ask to override your chdir() built-in function, then your PWD
72 environment variable will be kept up to date. (See
73 L<perlsub/Overriding Builtin Functions>.) Note that it will only be
74 kept up to date if all packages which use chdir import it from Cwd.
82 our $VERSION = '2.04';
84 use base qw/ Exporter /;
85 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
86 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
89 # The 'natural and safe form' for UNIX (pwd may be setuid root)
93 # `pwd` may fail e.g. if the disk is full
94 chomp($cwd) if defined $cwd;
98 # Since some ports may predefine cwd internally (e.g., NT)
99 # we take care not to override an existing definition for cwd().
101 unless(defined &cwd) {
102 # The pwd command is not available in some chroot(2)'ed environments
103 if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
104 *cwd = \&_backtick_pwd;
111 # set a reasonable (and very safe) default for fastgetcwd, in case it
112 # isn't redefined later (20001212 rspier)
115 # By Brandon S. Allbery
117 # Usage: $cwd = getcwd();
124 # Now a callout to an XSUB. We have to delay booting of the XSUB
125 # until the first time fastcwd is called since Cwd::cwd is needed in the
126 # building of perl when dynamic loading may be unavailable
131 XSLoader::load("Cwd");
134 return &Cwd::_fastcwd;
138 # Keeps track of current working directory in PWD environment var
146 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
147 my($dd,$di) = stat('.');
148 my($pd,$pi) = stat($ENV{'PWD'});
149 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
155 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
158 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
159 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
160 my($pd,$pi) = stat($2);
161 my($dd,$di) = stat($1);
162 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
170 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
171 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
172 chdir_init() unless $chdir_init;
174 if ($^O eq 'MSWin32') {
175 # get the full path name *before* the chdir()
176 $newpwd = Win32::GetFullPathName($newdir);
179 return 0 unless CORE::chdir $newdir;
182 return $ENV{'PWD'} = $ENV{'DEFAULT'}
184 elsif ($^O eq 'MacOS') {
185 return $ENV{'PWD'} = cwd();
187 elsif ($^O eq 'MSWin32') {
188 $ENV{'PWD'} = $newpwd;
192 if ($newdir =~ m#^/#s) {
193 $ENV{'PWD'} = $newdir;
195 my @curdir = split(m#/#,$ENV{'PWD'});
196 @curdir = ('') unless @curdir;
198 foreach $component (split(m#/#, $newdir)) {
199 next if $component eq '.';
200 pop(@curdir),next if $component eq '..';
201 push(@curdir,$component);
203 $ENV{'PWD'} = join('/',@curdir) || '/';
208 # Taken from Cwd.pm It is really getcwd with an optional
209 # parameter instead of '.'
214 my $start = @_ ? shift : '.';
215 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
217 unless (@cst = stat( $start ))
219 carp "stat($start): $!";
228 unless (opendir(PARENT, $dotdots))
230 carp "opendir($dotdots): $!";
233 unless (@cst = stat($dotdots))
235 carp "stat($dotdots): $!";
239 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
247 unless (defined ($dir = readdir(PARENT)))
249 carp "readdir($dotdots): $!";
253 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
255 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
258 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
260 } while (defined $dir);
261 chop($cwd) unless $cwd eq '/'; # drop the trailing /
265 # added function alias for those of us more
266 # used to the libc function. --tchrist 27-Jan-00
267 *realpath = \&abs_path;
271 my $path = @_ ? shift : '.';
272 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
273 my $realpath = getcwd();
274 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
278 # added function alias to follow principle of least surprise
279 # based on previous aliasing. --tchrist 27-Jan-00
280 *fast_realpath = \&fast_abs_path;
283 # --- PORTING SECTION ---
285 # VMS: $ENV{'DEFAULT'} points to default directory at all times
286 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
287 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
288 # in the process logical name table as the default device and directory
289 # seen by Perl. This may not be the same as the default device
290 # and directory seen by DCL after Perl exits, since the effects
291 # the CRTL chdir() function persist only until Perl exits.
294 return $ENV{'DEFAULT'};
298 return $ENV{'DEFAULT'} unless @_;
299 my $path = VMS::Filespec::pathify($_[0]);
300 croak("Invalid path name $_[0]") unless defined $path;
301 return VMS::Filespec::rmsexpand($path);
305 $ENV{'PWD'} = `cmd /c cd`;
307 $ENV{'PWD'} =~ s:\\:/:g ;
312 $ENV{'PWD'} = Win32::GetCwd();
313 $ENV{'PWD'} =~ s:\\:/:g ;
317 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
318 defined &Win32::GetCwd);
320 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
323 if (!defined &Dos::GetCwd) {
324 $ENV{'PWD'} = `command /c cd`;
326 $ENV{'PWD'} =~ s:\\:/:g ;
328 $ENV{'PWD'} = Dos::GetCwd();
334 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
340 my $path = @_ ? shift : '.';
341 my $realpath=`/usr/bin/fullpath -t $path`;
347 $ENV{'PWD'} = EPOC::getcwd();
352 no warnings; # assignments trigger 'subroutine redefined' warning
356 *getcwd = \&_vms_cwd;
357 *fastcwd = \&_vms_cwd;
358 *fastgetcwd = \&_vms_cwd;
359 *abs_path = \&_vms_abs_path;
360 *fast_abs_path = \&_vms_abs_path;
362 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
363 # We assume that &_NT_cwd is defined as an XSUB or in the core.
366 *fastcwd = \&_NT_cwd;
367 *fastgetcwd = \&_NT_cwd;
368 *abs_path = \&fast_abs_path;
370 elsif ($^O eq 'os2') {
371 # sys_cwd may keep the builtin command
372 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
376 *abs_path = \&fast_abs_path;
378 elsif ($^O eq 'dos') {
380 *getcwd = \&_dos_cwd;
381 *fastgetcwd = \&_dos_cwd;
382 *fastcwd = \&_dos_cwd;
383 *abs_path = \&fast_abs_path;
385 elsif ($^O eq 'qnx') {
387 *getcwd = \&_qnx_cwd;
388 *fastgetcwd = \&_qnx_cwd;
389 *fastcwd = \&_qnx_cwd;
390 *abs_path = \&_qnx_abs_path;
391 *fast_abs_path = \&_qnx_abs_path;
393 elsif ($^O eq 'cygwin') {
397 *abs_path = \&fast_abs_path;
399 elsif ($^O eq 'epoc') {
401 *getcwd = \&_epoc_cwd;
402 *fastgetcwd = \&_epoc_cwd;
403 *fastcwd = \&_epoc_cwd;
404 *abs_path = \&fast_abs_path;
406 elsif ($^O eq 'MacOS') {
410 *abs_path = \&fast_abs_path;
414 # package main; eval join('',<DATA>) || die $@; # quick test
419 BEGIN { import Cwd qw(:DEFAULT chdir); }
420 print join("\n", cwd, getcwd, fastcwd, "");
422 print join("\n", cwd, getcwd, fastcwd, "");