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);
175 my $xs_version = $VERSION;
176 $VERSION = eval $VERSION;
178 @ISA = qw/ Exporter /;
179 @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
180 push @EXPORT, qw(getdcwd) if $^O eq 'MSWin32';
181 @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
183 # sys_cwd may keep the builtin command
185 # All the functionality of this module may provided by builtins,
186 # there is no sense to process the rest of the file.
187 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
192 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
197 *fast_abs_path = \&sys_abspath if defined &sys_abspath;
198 *abs_path = \&fast_abs_path;
199 *realpath = \&fast_abs_path;
200 *fast_realpath = \&fast_abs_path;
205 # If loading the XS stuff doesn't work, we can fall back to pure perl
209 XSLoader::load( __PACKAGE__, $xs_version);
212 push @ISA, 'DynaLoader';
213 __PACKAGE__->bootstrap( $xs_version );
217 # Must be after the DynaLoader stuff:
218 $VERSION = eval $VERSION;
220 # Big nasty table of function aliases
226 getcwd => '_vms_cwd',
227 fastcwd => '_vms_cwd',
228 fastgetcwd => '_vms_cwd',
229 abs_path => '_vms_abs_path',
230 fast_abs_path => '_vms_abs_path',
235 # We assume that &_NT_cwd is defined as an XSUB or in the core.
238 fastcwd => '_NT_cwd',
239 fastgetcwd => '_NT_cwd',
240 abs_path => 'fast_abs_path',
241 realpath => 'fast_abs_path',
247 getcwd => '_dos_cwd',
248 fastgetcwd => '_dos_cwd',
249 fastcwd => '_dos_cwd',
250 abs_path => 'fast_abs_path',
256 getcwd => '_qnx_cwd',
257 fastgetcwd => '_qnx_cwd',
258 fastcwd => '_qnx_cwd',
259 abs_path => '_qnx_abs_path',
260 fast_abs_path => '_qnx_abs_path',
268 abs_path => 'fast_abs_path',
269 realpath => 'fast_abs_path',
275 getcwd => '_epoc_cwd',
276 fastgetcwd => '_epoc_cwd',
277 fastcwd => '_epoc_cwd',
278 abs_path => 'fast_abs_path',
286 abs_path => 'fast_abs_path',
290 $METHOD_MAP{NT} = $METHOD_MAP{MSWin32};
291 $METHOD_MAP{nto} = $METHOD_MAP{qnx};
294 # Find the pwd command in the expected locations. We assume these
295 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
296 # so everything works under taint mode.
298 foreach my $try ('/bin/pwd',
300 '/QOpenSys/bin/pwd', # OS/400 PASE.
308 my $found_pwd_cmd = defined($pwd_cmd);
310 # Isn't this wrong? _backtick_pwd() will fail if somenone has
311 # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
312 # See [perl #16774]. --jhi
317 sub _carp { require Carp; Carp::carp(@_) }
318 sub _croak { require Carp; Carp::croak(@_) }
320 # The 'natural and safe form' for UNIX (pwd may be setuid root)
322 # Localize %ENV entries in a way that won't create new hash keys
323 my @localize = grep exists $ENV{$_}, qw(PATH IFS CDPATH ENV BASH_ENV);
324 local @ENV{@localize};
326 my $cwd = `$pwd_cmd`;
327 # Belt-and-suspenders in case someone said "undef $/".
329 # `pwd` may fail e.g. if the disk is full
330 chomp($cwd) if defined $cwd;
334 # Since some ports may predefine cwd internally (e.g., NT)
335 # we take care not to override an existing definition for cwd().
337 unless ($METHOD_MAP{$^O}{cwd} or defined &cwd) {
338 # The pwd command is not available in some chroot(2)'ed environments
339 my $sep = $Config::Config{path_sep} || ':';
340 my $os = $^O; # Protect $^O from tainting
343 # Try again to find a pwd, this time searching the whole PATH.
344 if (defined $ENV{PATH} and $os ne 'MSWin32') { # no pwd on Windows
345 my @candidates = split($sep, $ENV{PATH});
346 while (!$found_pwd_cmd and @candidates) {
347 my $candidate = shift @candidates;
348 $found_pwd_cmd = 1 if -x "$candidate/pwd";
352 # MacOS has some special magic to make `pwd` work.
353 if( $os eq 'MacOS' || $found_pwd_cmd )
355 *cwd = \&_backtick_pwd;
362 if ($^O eq 'cygwin') {
363 # We need to make sure cwd() is called with no args, because it's
364 # got an arg-less prototype and will die if args are present.
366 my $orig_cwd = \&cwd;
367 *cwd = sub { &$orig_cwd() }
371 # set a reasonable (and very safe) default for fastgetcwd, in case it
372 # isn't redefined later (20001212 rspier)
375 # A non-XS version of getcwd() - also used to bootstrap the perl build
376 # process, when miniperl is running and no XS loading happens.
384 # Usage: $cwd = &fastcwd;
386 # This is a faster version of getcwd. It's also more dangerous because
387 # you might chdir out of a directory that you can't chdir back into.
390 my($odev, $oino, $cdev, $cino, $tdev, $tino);
394 my($orig_cdev, $orig_cino) = stat('.');
395 ($cdev, $cino) = ($orig_cdev, $orig_cino);
398 ($odev, $oino) = ($cdev, $cino);
399 CORE::chdir('..') || return undef;
400 ($cdev, $cino) = stat('.');
401 last if $odev == $cdev && $oino == $cino;
402 opendir(DIR, '.') || return undef;
404 $direntry = readdir(DIR);
405 last unless defined $direntry;
406 next if $direntry eq '.';
407 next if $direntry eq '..';
409 ($tdev, $tino) = lstat($direntry);
410 last unless $tdev != $odev || $tino != $oino;
413 return undef unless defined $direntry; # should never happen
414 unshift(@path, $direntry);
416 $path = '/' . join('/', @path);
417 if ($^O eq 'apollo') { $path = "/".$path; }
418 # At this point $path may be tainted (if tainting) and chdir would fail.
419 # Untaint it then check that we landed where we started.
420 $path =~ /^(.*)\z/s # untaint
421 && CORE::chdir($1) or return undef;
422 ($cdev, $cino) = stat('.');
423 die "Unstable directory path, current directory changed unexpectedly"
424 if $cdev != $orig_cdev || $cino != $orig_cino;
427 if (not defined &fastcwd) { *fastcwd = \&fastcwd_ }
430 # Keeps track of current working directory in PWD environment var
438 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
439 my($dd,$di) = stat('.');
440 my($pd,$pi) = stat($ENV{'PWD'});
441 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
447 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
450 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
451 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
452 my($pd,$pi) = stat($2);
453 my($dd,$di) = stat($1);
454 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
462 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
463 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
464 chdir_init() unless $chdir_init;
466 if ($^O eq 'MSWin32') {
467 # get the full path name *before* the chdir()
468 $newpwd = Win32::GetFullPathName($newdir);
471 return 0 unless CORE::chdir $newdir;
474 return $ENV{'PWD'} = $ENV{'DEFAULT'}
476 elsif ($^O eq 'MacOS') {
477 return $ENV{'PWD'} = cwd();
479 elsif ($^O eq 'MSWin32') {
480 $ENV{'PWD'} = $newpwd;
484 if (ref $newdir eq 'GLOB') { # in case a file/dir handle is passed in
486 } elsif ($newdir =~ m#^/#s) {
487 $ENV{'PWD'} = $newdir;
489 my @curdir = split(m#/#,$ENV{'PWD'});
490 @curdir = ('') unless @curdir;
492 foreach $component (split(m#/#, $newdir)) {
493 next if $component eq '.';
494 pop(@curdir),next if $component eq '..';
495 push(@curdir,$component);
497 $ENV{'PWD'} = join('/',@curdir) || '/';
505 my $start = @_ ? shift : '.';
506 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
508 unless (@cst = stat( $start ))
510 _carp("stat($start): $!");
515 # Make sure we can be invoked on plain files, not just directories.
516 # NOTE that this routine assumes that '/' is the only directory separator.
518 my ($dir, $file) = $start =~ m{^(.*)/(.+)$}
519 or return cwd() . '/' . $start;
521 # Can't use "-l _" here, because the previous stat was a stat(), not an lstat().
523 my $link_target = readlink($start);
524 die "Can't resolve link $start: $!" unless defined $link_target;
527 $link_target = $dir . '/' . $link_target
528 unless File::Spec->file_name_is_absolute($link_target);
530 return abs_path($link_target);
533 return $dir ? abs_path($dir) . "/$file" : "/$file";
543 unless (opendir(PARENT, $dotdots))
545 # probably a permissions issue. Try the native command.
546 return File::Spec->rel2abs( $start, _backtick_pwd() );
548 unless (@cst = stat($dotdots))
550 _carp("stat($dotdots): $!");
554 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
562 unless (defined ($dir = readdir(PARENT)))
564 _carp("readdir($dotdots): $!");
568 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
570 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
573 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
575 } while (defined $dir);
576 chop($cwd) unless $cwd eq '/'; # drop the trailing /
583 local $ENV{PWD} = $ENV{PWD} || ''; # Guard against clobberage
586 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
588 # Detaint else we'll explode in taint mode. This is safe because
589 # we're not doing anything dangerous with it.
590 ($path) = $path =~ /(.*)/;
591 ($cwd) = $cwd =~ /(.*)/;
594 _croak("$path: No such file or directory");
598 # Make sure we can be invoked on plain files, not just directories.
600 my ($vol, $dir, $file) = File::Spec->splitpath($path);
601 return File::Spec->catfile($cwd, $path) unless length $dir;
604 my $link_target = readlink($path);
605 die "Can't resolve link $path: $!" unless defined $link_target;
607 $link_target = File::Spec->catpath($vol, $dir, $link_target)
608 unless File::Spec->file_name_is_absolute($link_target);
610 return fast_abs_path($link_target);
613 return $dir eq File::Spec->rootdir
614 ? File::Spec->catpath($vol, $dir, $file)
615 : fast_abs_path(File::Spec->catpath($vol, $dir, '')) . '/' . $file;
618 if (!CORE::chdir($path)) {
619 _croak("Cannot chdir to $path: $!");
621 my $realpath = getcwd();
622 if (! ((-d $cwd) && (CORE::chdir($cwd)))) {
623 _croak("Cannot chdir back to $cwd: $!");
628 # added function alias to follow principle of least surprise
629 # based on previous aliasing. --tchrist 27-Jan-00
630 *fast_realpath = \&fast_abs_path;
633 # --- PORTING SECTION ---
635 # VMS: $ENV{'DEFAULT'} points to default directory at all times
636 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
637 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
638 # in the process logical name table as the default device and directory
639 # seen by Perl. This may not be the same as the default device
640 # and directory seen by DCL after Perl exits, since the effects
641 # the CRTL chdir() function persist only until Perl exits.
644 return $ENV{'DEFAULT'};
648 return $ENV{'DEFAULT'} unless @_;
652 my $link_target = readlink($path);
653 die "Can't resolve link $path: $!" unless defined $link_target;
655 return _vms_abs_path($link_target);
658 if (defined &VMS::Filespec::vms_realpath) {
660 if ($path =~ m#(?<=\^)/# ) {
662 return VMS::Filespec::vms_realpath($path);
667 my $new_path = VMS::Filespec::vms_realname($path);
669 # Perl expects directories to be in directory format
670 $new_path = VMS::Filespec::pathify($new_path) if -d $path;
674 # Fallback to older algorithm if correct ones are not
677 # may need to turn foo.dir into [.foo]
678 my $pathified = VMS::Filespec::pathify($path);
679 $path = $pathified if defined $pathified;
681 return VMS::Filespec::rmsexpand($path);
685 $ENV{'PWD'} = `cmd /c cd`;
687 $ENV{'PWD'} =~ s:\\:/:g ;
692 if (defined &DynaLoader::boot_DynaLoader) {
693 $ENV{'PWD'} = Win32::GetCwd();
696 chomp($ENV{'PWD'} = `cd`);
698 $ENV{'PWD'} =~ s:\\:/:g ;
702 *_NT_cwd = defined &Win32::GetCwd ? \&_win32_cwd : \&_os2_cwd;
705 if (!defined &Dos::GetCwd) {
706 $ENV{'PWD'} = `command /c cd`;
708 $ENV{'PWD'} =~ s:\\:/:g ;
710 $ENV{'PWD'} = Dos::GetCwd();
716 local $ENV{PATH} = '';
717 local $ENV{CDPATH} = '';
718 local $ENV{ENV} = '';
719 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
725 local $ENV{PATH} = '';
726 local $ENV{CDPATH} = '';
727 local $ENV{ENV} = '';
728 my $path = @_ ? shift : '.';
731 defined( open(REALPATH, '-|') || exec '/usr/bin/fullpath', '-t', $path ) or
732 die "Can't open /usr/bin/fullpath: $!";
733 my $realpath = <REALPATH>;
740 $ENV{'PWD'} = EPOC::getcwd();
745 # Now that all the base-level functions are set up, alias the
746 # user-level functions to the right places
748 if (exists $METHOD_MAP{$^O}) {
749 my $map = $METHOD_MAP{$^O};
750 foreach my $name (keys %$map) {
751 local $^W = 0; # assignments trigger 'subroutine redefined' warning
753 *{$name} = \&{$map->{$name}};
757 # In case the XS version doesn't load.
758 *abs_path = \&_perl_abs_path unless defined &abs_path;
759 *getcwd = \&_perl_getcwd unless defined &getcwd;
761 # added function alias for those of us more
762 # used to the libc function. --tchrist 27-Jan-00
763 *realpath = \&abs_path;