5 Cwd - get pathname of current working directory
13 my $abs_path = abs_path($file);
17 This module provides functions for determining the pathname of the
18 current working directory. It is recommended that getcwd (or another
19 *cwd() function) be used in I<all> code to ensure portability.
21 By default, it exports the functions cwd(), getcwd(), fastcwd(), and
22 fastgetcwd() (and, on Win32, getdcwd()) into the caller's namespace.
25 =head2 getcwd and friends
27 Each of these functions are called without arguments and return the
28 absolute path of the current working directory.
36 Returns the current working directory.
38 Exposes the POSIX function getcwd(3) or re-implements it if it's not
45 The cwd() is the most natural form for the current architecture. For
46 most systems it is identical to `pwd` (but without the trailing line
53 A more dangerous version of getcwd(), but potentially faster.
55 It might conceivably chdir() you out of a directory that it can't
56 chdir() you back into. If fastcwd encounters a problem it will return
57 undef but will probably leave you in a different directory. For a
58 measure of extra security, if everything appears to have worked, the
59 fastcwd() function will check that it leaves you in the same directory
60 that it started in. If it has changed it will C<die> with the message
61 "Unstable directory path, current directory changed
62 unexpectedly". That should never happen.
66 my $cwd = fastgetcwd();
68 The fastgetcwd() function is provided as a synonym for cwd().
73 my $cwd = getdcwd('C:');
75 The getdcwd() function is also provided on Win32 to get the current working
76 directory on the specified drive, since Windows maintains a separate current
77 working directory for each drive. If no drive is specified then the current
80 This function simply calls the Microsoft C library _getdcwd() function.
85 =head2 abs_path and friends
87 These functions are exported only on request. They each take a single
88 argument and return the absolute pathname for it. If no argument is
89 given they'll use the current working directory.
95 my $abs_path = abs_path($file);
97 Uses the same algorithm as getcwd(). Symbolic links and relative-path
98 components ("." and "..") are resolved to return the canonical
99 pathname, just like realpath(3).
103 my $abs_path = realpath($file);
105 A synonym for abs_path().
109 my $abs_path = fast_abs_path($file);
111 A more dangerous, but potentially faster version of abs_path.
117 If you ask to override your chdir() built-in function,
121 then your PWD environment variable will be kept up to date. Note that
122 it will only be kept up to date if all packages which use chdir import
132 Since the path seperators are different on some operating systems ('/'
133 on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
134 modules wherever portability is a concern.
138 Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
139 functions are all aliases for the C<cwd()> function, which, on Mac OS,
140 calls `pwd`. Likewise, the C<abs_path()> function is an alias for
147 Originally by the perl5-porters.
149 Maintained by Ken Williams <KWILLIAMS@cpan.org>
153 Copyright (c) 2004 by the Perl 5 Porters. All rights reserved.
155 This program is free software; you can redistribute it and/or modify
156 it under the same terms as Perl itself.
158 Portions of the C code in this library are copyright (c) 1994 by the
159 Regents of the University of California. All rights reserved. The
160 license on this code is compatible with the licensing of the rest of
161 the distribution - please see the source code in F<Cwd.xs> for the
172 use vars qw(@ISA @EXPORT @EXPORT_OK $VERSION);
174 $VERSION = '3.28_01';
175 $VERSION = eval $VERSION;
177 @ISA = qw/ Exporter /;
178 @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
179 push @EXPORT, qw(getdcwd) if $^O eq 'MSWin32';
180 @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
182 # sys_cwd may keep the builtin command
184 # All the functionality of this module may provided by builtins,
185 # there is no sense to process the rest of the file.
186 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
191 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
196 *fast_abs_path = \&sys_abspath if defined &sys_abspath;
197 *abs_path = \&fast_abs_path;
198 *realpath = \&fast_abs_path;
199 *fast_realpath = \&fast_abs_path;
204 # If loading the XS stuff doesn't work, we can fall back to pure perl
208 XSLoader::load( __PACKAGE__, $VERSION );
211 push @ISA, 'DynaLoader';
212 __PACKAGE__->bootstrap( $VERSION );
216 # Must be after the DynaLoader stuff:
217 $VERSION = eval $VERSION;
219 # Big nasty table of function aliases
225 getcwd => '_vms_cwd',
226 fastcwd => '_vms_cwd',
227 fastgetcwd => '_vms_cwd',
228 abs_path => '_vms_abs_path',
229 fast_abs_path => '_vms_abs_path',
234 # We assume that &_NT_cwd is defined as an XSUB or in the core.
237 fastcwd => '_NT_cwd',
238 fastgetcwd => '_NT_cwd',
239 abs_path => 'fast_abs_path',
240 realpath => 'fast_abs_path',
246 getcwd => '_dos_cwd',
247 fastgetcwd => '_dos_cwd',
248 fastcwd => '_dos_cwd',
249 abs_path => 'fast_abs_path',
255 getcwd => '_qnx_cwd',
256 fastgetcwd => '_qnx_cwd',
257 fastcwd => '_qnx_cwd',
258 abs_path => '_qnx_abs_path',
259 fast_abs_path => '_qnx_abs_path',
267 abs_path => 'fast_abs_path',
268 realpath => 'fast_abs_path',
274 getcwd => '_epoc_cwd',
275 fastgetcwd => '_epoc_cwd',
276 fastcwd => '_epoc_cwd',
277 abs_path => 'fast_abs_path',
285 abs_path => 'fast_abs_path',
289 $METHOD_MAP{NT} = $METHOD_MAP{MSWin32};
290 $METHOD_MAP{nto} = $METHOD_MAP{qnx};
293 # Find the pwd command in the expected locations. We assume these
294 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
295 # so everything works under taint mode.
297 foreach my $try ('/bin/pwd',
299 '/QOpenSys/bin/pwd', # OS/400 PASE.
307 my $found_pwd_cmd = defined($pwd_cmd);
309 # Isn't this wrong? _backtick_pwd() will fail if somenone has
310 # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
311 # See [perl #16774]. --jhi
316 sub _carp { require Carp; Carp::carp(@_) }
317 sub _croak { require Carp; Carp::croak(@_) }
319 # The 'natural and safe form' for UNIX (pwd may be setuid root)
321 # Localize %ENV entries in a way that won't create new hash keys
322 my @localize = grep exists $ENV{$_}, qw(PATH IFS CDPATH ENV BASH_ENV);
323 local @ENV{@localize};
325 my $cwd = `$pwd_cmd`;
326 # Belt-and-suspenders in case someone said "undef $/".
328 # `pwd` may fail e.g. if the disk is full
329 chomp($cwd) if defined $cwd;
333 # Since some ports may predefine cwd internally (e.g., NT)
334 # we take care not to override an existing definition for cwd().
336 unless ($METHOD_MAP{$^O}{cwd} or defined &cwd) {
337 # The pwd command is not available in some chroot(2)'ed environments
338 my $sep = $Config::Config{path_sep} || ':';
339 my $os = $^O; # Protect $^O from tainting
342 # Try again to find a pwd, this time searching the whole PATH.
343 if (defined $ENV{PATH} and $os ne 'MSWin32') { # no pwd on Windows
344 my @candidates = split($sep, $ENV{PATH});
345 while (!$found_pwd_cmd and @candidates) {
346 my $candidate = shift @candidates;
347 $found_pwd_cmd = 1 if -x "$candidate/pwd";
351 # MacOS has some special magic to make `pwd` work.
352 if( $os eq 'MacOS' || $found_pwd_cmd )
354 *cwd = \&_backtick_pwd;
361 if ($^O eq 'cygwin') {
362 # We need to make sure cwd() is called with no args, because it's
363 # got an arg-less prototype and will die if args are present.
365 my $orig_cwd = \&cwd;
366 *cwd = sub { &$orig_cwd() }
370 # set a reasonable (and very safe) default for fastgetcwd, in case it
371 # isn't redefined later (20001212 rspier)
374 # A non-XS version of getcwd() - also used to bootstrap the perl build
375 # process, when miniperl is running and no XS loading happens.
383 # Usage: $cwd = &fastcwd;
385 # This is a faster version of getcwd. It's also more dangerous because
386 # you might chdir out of a directory that you can't chdir back into.
389 my($odev, $oino, $cdev, $cino, $tdev, $tino);
393 my($orig_cdev, $orig_cino) = stat('.');
394 ($cdev, $cino) = ($orig_cdev, $orig_cino);
397 ($odev, $oino) = ($cdev, $cino);
398 CORE::chdir('..') || return undef;
399 ($cdev, $cino) = stat('.');
400 last if $odev == $cdev && $oino == $cino;
401 opendir(DIR, '.') || return undef;
403 $direntry = readdir(DIR);
404 last unless defined $direntry;
405 next if $direntry eq '.';
406 next if $direntry eq '..';
408 ($tdev, $tino) = lstat($direntry);
409 last unless $tdev != $odev || $tino != $oino;
412 return undef unless defined $direntry; # should never happen
413 unshift(@path, $direntry);
415 $path = '/' . join('/', @path);
416 if ($^O eq 'apollo') { $path = "/".$path; }
417 # At this point $path may be tainted (if tainting) and chdir would fail.
418 # Untaint it then check that we landed where we started.
419 $path =~ /^(.*)\z/s # untaint
420 && CORE::chdir($1) or return undef;
421 ($cdev, $cino) = stat('.');
422 die "Unstable directory path, current directory changed unexpectedly"
423 if $cdev != $orig_cdev || $cino != $orig_cino;
426 if (not defined &fastcwd) { *fastcwd = \&fastcwd_ }
429 # Keeps track of current working directory in PWD environment var
437 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
438 my($dd,$di) = stat('.');
439 my($pd,$pi) = stat($ENV{'PWD'});
440 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
446 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
449 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
450 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
451 my($pd,$pi) = stat($2);
452 my($dd,$di) = stat($1);
453 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
461 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
462 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
463 chdir_init() unless $chdir_init;
465 if ($^O eq 'MSWin32') {
466 # get the full path name *before* the chdir()
467 $newpwd = Win32::GetFullPathName($newdir);
470 return 0 unless CORE::chdir $newdir;
473 return $ENV{'PWD'} = $ENV{'DEFAULT'}
475 elsif ($^O eq 'MacOS') {
476 return $ENV{'PWD'} = cwd();
478 elsif ($^O eq 'MSWin32') {
479 $ENV{'PWD'} = $newpwd;
483 if (ref $newdir eq 'GLOB') { # in case a file/dir handle is passed in
485 } elsif ($newdir =~ m#^/#s) {
486 $ENV{'PWD'} = $newdir;
488 my @curdir = split(m#/#,$ENV{'PWD'});
489 @curdir = ('') unless @curdir;
491 foreach $component (split(m#/#, $newdir)) {
492 next if $component eq '.';
493 pop(@curdir),next if $component eq '..';
494 push(@curdir,$component);
496 $ENV{'PWD'} = join('/',@curdir) || '/';
504 my $start = @_ ? shift : '.';
505 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
507 unless (@cst = stat( $start ))
509 _carp("stat($start): $!");
514 # Make sure we can be invoked on plain files, not just directories.
515 # NOTE that this routine assumes that '/' is the only directory separator.
517 my ($dir, $file) = $start =~ m{^(.*)/(.+)$}
518 or return cwd() . '/' . $start;
520 # Can't use "-l _" here, because the previous stat was a stat(), not an lstat().
522 my $link_target = readlink($start);
523 die "Can't resolve link $start: $!" unless defined $link_target;
526 $link_target = $dir . '/' . $link_target
527 unless File::Spec->file_name_is_absolute($link_target);
529 return abs_path($link_target);
532 return $dir ? abs_path($dir) . "/$file" : "/$file";
542 unless (opendir(PARENT, $dotdots))
544 # probably a permissions issue. Try the native command.
545 return File::Spec->rel2abs( $start, _backtick_pwd() );
547 unless (@cst = stat($dotdots))
549 _carp("stat($dotdots): $!");
553 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
561 unless (defined ($dir = readdir(PARENT)))
563 _carp("readdir($dotdots): $!");
567 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
569 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
572 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
574 } while (defined $dir);
575 chop($cwd) unless $cwd eq '/'; # drop the trailing /
582 local $ENV{PWD} = $ENV{PWD} || ''; # Guard against clobberage
585 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
587 # Detaint else we'll explode in taint mode. This is safe because
588 # we're not doing anything dangerous with it.
589 ($path) = $path =~ /(.*)/;
590 ($cwd) = $cwd =~ /(.*)/;
593 _croak("$path: No such file or directory");
597 # Make sure we can be invoked on plain files, not just directories.
599 my ($vol, $dir, $file) = File::Spec->splitpath($path);
600 return File::Spec->catfile($cwd, $path) unless length $dir;
603 my $link_target = readlink($path);
604 die "Can't resolve link $path: $!" unless defined $link_target;
606 $link_target = File::Spec->catpath($vol, $dir, $link_target)
607 unless File::Spec->file_name_is_absolute($link_target);
609 return fast_abs_path($link_target);
612 return $dir eq File::Spec->rootdir
613 ? File::Spec->catpath($vol, $dir, $file)
614 : fast_abs_path(File::Spec->catpath($vol, $dir, '')) . '/' . $file;
617 if (!CORE::chdir($path)) {
618 _croak("Cannot chdir to $path: $!");
620 my $realpath = getcwd();
621 if (! ((-d $cwd) && (CORE::chdir($cwd)))) {
622 _croak("Cannot chdir back to $cwd: $!");
627 # added function alias to follow principle of least surprise
628 # based on previous aliasing. --tchrist 27-Jan-00
629 *fast_realpath = \&fast_abs_path;
632 # --- PORTING SECTION ---
634 # VMS: $ENV{'DEFAULT'} points to default directory at all times
635 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
636 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
637 # in the process logical name table as the default device and directory
638 # seen by Perl. This may not be the same as the default device
639 # and directory seen by DCL after Perl exits, since the effects
640 # the CRTL chdir() function persist only until Perl exits.
643 return $ENV{'DEFAULT'};
647 return $ENV{'DEFAULT'} unless @_;
651 my $link_target = readlink($path);
652 die "Can't resolve link $path: $!" unless defined $link_target;
654 return _vms_abs_path($link_target);
657 if (defined &VMS::Filespec::vms_realpath) {
659 if ($path =~ m#(?<=\^)/# ) {
661 return VMS::Filespec::vms_realpath($path);
666 my $new_path = VMS::Filespec::vms_realname($path);
668 # Perl expects directories to be in directory format
669 $new_path = VMS::Filespec::pathify($new_path) if -d $path;
673 # Fallback to older algorithm if correct ones are not
676 # may need to turn foo.dir into [.foo]
677 my $pathified = VMS::Filespec::pathify($path);
678 $path = $pathified if defined $pathified;
680 return VMS::Filespec::rmsexpand($path);
684 $ENV{'PWD'} = `cmd /c cd`;
686 $ENV{'PWD'} =~ s:\\:/:g ;
691 if (defined &DynaLoader::boot_DynaLoader) {
692 $ENV{'PWD'} = Win32::GetCwd();
695 chomp($ENV{'PWD'} = `cd`);
697 $ENV{'PWD'} =~ s:\\:/:g ;
701 *_NT_cwd = defined &Win32::GetCwd ? \&_win32_cwd : \&_os2_cwd;
704 if (!defined &Dos::GetCwd) {
705 $ENV{'PWD'} = `command /c cd`;
707 $ENV{'PWD'} =~ s:\\:/:g ;
709 $ENV{'PWD'} = Dos::GetCwd();
715 local $ENV{PATH} = '';
716 local $ENV{CDPATH} = '';
717 local $ENV{ENV} = '';
718 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
724 local $ENV{PATH} = '';
725 local $ENV{CDPATH} = '';
726 local $ENV{ENV} = '';
727 my $path = @_ ? shift : '.';
730 defined( open(REALPATH, '-|') || exec '/usr/bin/fullpath', '-t', $path ) or
731 die "Can't open /usr/bin/fullpath: $!";
732 my $realpath = <REALPATH>;
739 $ENV{'PWD'} = EPOC::getcwd();
744 # Now that all the base-level functions are set up, alias the
745 # user-level functions to the right places
747 if (exists $METHOD_MAP{$^O}) {
748 my $map = $METHOD_MAP{$^O};
749 foreach my $name (keys %$map) {
750 local $^W = 0; # assignments trigger 'subroutine redefined' warning
752 *{$name} = \&{$map->{$name}};
756 # In case the XS version doesn't load.
757 *abs_path = \&_perl_abs_path unless defined &abs_path;
758 *getcwd = \&_perl_getcwd unless defined &getcwd;
760 # added function alias for those of us more
761 # used to the libc function. --tchrist 27-Jan-00
762 *realpath = \&abs_path;