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 separators 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 # Need to look up the feature settings on VMS. The preferred way is to use the
206 # VMS::Feature module, but that may not be available to dual life modules.
211 if (eval { local $SIG{__DIE__}; require VMS::Feature; }) {
212 $use_vms_feature = 1;
217 # Need to look up the UNIX report mode. This may become a dynamic mode
221 if ($use_vms_feature) {
222 $unix_rpt = VMS::Feature::current("filename_unix_report");
224 my $env_unix_rpt = $ENV{'DECC$FILENAME_UNIX_REPORT'} || '';
225 $unix_rpt = $env_unix_rpt =~ /^[ET1]/i;
230 # Need to look up the EFS character set mode. This may become a dynamic
231 # mode in the future.
234 if ($use_vms_feature) {
235 $efs = VMS::Feature::current("efs_charset");
237 my $env_efs = $ENV{'DECC$EFS_CHARSET'} || '';
238 $efs = $env_efs =~ /^[ET1]/i;
244 # If loading the XS stuff doesn't work, we can fall back to pure perl
248 XSLoader::load( __PACKAGE__, $xs_version);
251 push @ISA, 'DynaLoader';
252 __PACKAGE__->bootstrap( $xs_version );
256 # Big nasty table of function aliases
262 getcwd => '_vms_cwd',
263 fastcwd => '_vms_cwd',
264 fastgetcwd => '_vms_cwd',
265 abs_path => '_vms_abs_path',
266 fast_abs_path => '_vms_abs_path',
271 # We assume that &_NT_cwd is defined as an XSUB or in the core.
274 fastcwd => '_NT_cwd',
275 fastgetcwd => '_NT_cwd',
276 abs_path => 'fast_abs_path',
277 realpath => 'fast_abs_path',
283 getcwd => '_dos_cwd',
284 fastgetcwd => '_dos_cwd',
285 fastcwd => '_dos_cwd',
286 abs_path => 'fast_abs_path',
289 # QNX4. QNX6 has a $os of 'nto'.
293 getcwd => '_qnx_cwd',
294 fastgetcwd => '_qnx_cwd',
295 fastcwd => '_qnx_cwd',
296 abs_path => '_qnx_abs_path',
297 fast_abs_path => '_qnx_abs_path',
305 abs_path => 'fast_abs_path',
306 realpath => 'fast_abs_path',
312 getcwd => '_epoc_cwd',
313 fastgetcwd => '_epoc_cwd',
314 fastcwd => '_epoc_cwd',
315 abs_path => 'fast_abs_path',
323 abs_path => 'fast_abs_path',
327 $METHOD_MAP{NT} = $METHOD_MAP{MSWin32};
330 # Find the pwd command in the expected locations. We assume these
331 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
332 # so everything works under taint mode.
334 foreach my $try ('/bin/pwd',
336 '/QOpenSys/bin/pwd', # OS/400 PASE.
344 my $found_pwd_cmd = defined($pwd_cmd);
346 # Isn't this wrong? _backtick_pwd() will fail if somenone has
347 # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
348 # See [perl #16774]. --jhi
353 sub _carp { require Carp; Carp::carp(@_) }
354 sub _croak { require Carp; Carp::croak(@_) }
356 # The 'natural and safe form' for UNIX (pwd may be setuid root)
358 # Localize %ENV entries in a way that won't create new hash keys
359 my @localize = grep exists $ENV{$_}, qw(PATH IFS CDPATH ENV BASH_ENV);
360 local @ENV{@localize};
362 my $cwd = `$pwd_cmd`;
363 # Belt-and-suspenders in case someone said "undef $/".
365 # `pwd` may fail e.g. if the disk is full
366 chomp($cwd) if defined $cwd;
370 # Since some ports may predefine cwd internally (e.g., NT)
371 # we take care not to override an existing definition for cwd().
373 unless ($METHOD_MAP{$^O}{cwd} or defined &cwd) {
374 # The pwd command is not available in some chroot(2)'ed environments
375 my $sep = $Config::Config{path_sep} || ':';
376 my $os = $^O; # Protect $^O from tainting
379 # Try again to find a pwd, this time searching the whole PATH.
380 if (defined $ENV{PATH} and $os ne 'MSWin32') { # no pwd on Windows
381 my @candidates = split($sep, $ENV{PATH});
382 while (!$found_pwd_cmd and @candidates) {
383 my $candidate = shift @candidates;
384 $found_pwd_cmd = 1 if -x "$candidate/pwd";
388 # MacOS has some special magic to make `pwd` work.
389 if( $os eq 'MacOS' || $found_pwd_cmd )
391 *cwd = \&_backtick_pwd;
398 if ($^O eq 'cygwin') {
399 # We need to make sure cwd() is called with no args, because it's
400 # got an arg-less prototype and will die if args are present.
402 my $orig_cwd = \&cwd;
403 *cwd = sub { &$orig_cwd() }
407 # set a reasonable (and very safe) default for fastgetcwd, in case it
408 # isn't redefined later (20001212 rspier)
411 # A non-XS version of getcwd() - also used to bootstrap the perl build
412 # process, when miniperl is running and no XS loading happens.
420 # Usage: $cwd = &fastcwd;
422 # This is a faster version of getcwd. It's also more dangerous because
423 # you might chdir out of a directory that you can't chdir back into.
426 my($odev, $oino, $cdev, $cino, $tdev, $tino);
430 my($orig_cdev, $orig_cino) = stat('.');
431 ($cdev, $cino) = ($orig_cdev, $orig_cino);
434 ($odev, $oino) = ($cdev, $cino);
435 CORE::chdir('..') || return undef;
436 ($cdev, $cino) = stat('.');
437 last if $odev == $cdev && $oino == $cino;
438 opendir(DIR, '.') || return undef;
440 $direntry = readdir(DIR);
441 last unless defined $direntry;
442 next if $direntry eq '.';
443 next if $direntry eq '..';
445 ($tdev, $tino) = lstat($direntry);
446 last unless $tdev != $odev || $tino != $oino;
449 return undef unless defined $direntry; # should never happen
450 unshift(@path, $direntry);
452 $path = '/' . join('/', @path);
453 if ($^O eq 'apollo') { $path = "/".$path; }
454 # At this point $path may be tainted (if tainting) and chdir would fail.
455 # Untaint it then check that we landed where we started.
456 $path =~ /^(.*)\z/s # untaint
457 && CORE::chdir($1) or return undef;
458 ($cdev, $cino) = stat('.');
459 die "Unstable directory path, current directory changed unexpectedly"
460 if $cdev != $orig_cdev || $cino != $orig_cino;
463 if (not defined &fastcwd) { *fastcwd = \&fastcwd_ }
466 # Keeps track of current working directory in PWD environment var
474 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
475 my($dd,$di) = stat('.');
476 my($pd,$pi) = stat($ENV{'PWD'});
477 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
483 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
486 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
487 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
488 my($pd,$pi) = stat($2);
489 my($dd,$di) = stat($1);
490 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
498 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
499 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
500 chdir_init() unless $chdir_init;
502 if ($^O eq 'MSWin32') {
503 # get the full path name *before* the chdir()
504 $newpwd = Win32::GetFullPathName($newdir);
507 return 0 unless CORE::chdir $newdir;
510 return $ENV{'PWD'} = $ENV{'DEFAULT'}
512 elsif ($^O eq 'MacOS') {
513 return $ENV{'PWD'} = cwd();
515 elsif ($^O eq 'MSWin32') {
516 $ENV{'PWD'} = $newpwd;
520 if (ref $newdir eq 'GLOB') { # in case a file/dir handle is passed in
522 } elsif ($newdir =~ m#^/#s) {
523 $ENV{'PWD'} = $newdir;
525 my @curdir = split(m#/#,$ENV{'PWD'});
526 @curdir = ('') unless @curdir;
528 foreach $component (split(m#/#, $newdir)) {
529 next if $component eq '.';
530 pop(@curdir),next if $component eq '..';
531 push(@curdir,$component);
533 $ENV{'PWD'} = join('/',@curdir) || '/';
541 my $start = @_ ? shift : '.';
542 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
544 unless (@cst = stat( $start ))
546 _carp("stat($start): $!");
551 # Make sure we can be invoked on plain files, not just directories.
552 # NOTE that this routine assumes that '/' is the only directory separator.
554 my ($dir, $file) = $start =~ m{^(.*)/(.+)$}
555 or return cwd() . '/' . $start;
557 # Can't use "-l _" here, because the previous stat was a stat(), not an lstat().
559 my $link_target = readlink($start);
560 die "Can't resolve link $start: $!" unless defined $link_target;
563 $link_target = $dir . '/' . $link_target
564 unless File::Spec->file_name_is_absolute($link_target);
566 return abs_path($link_target);
569 return $dir ? abs_path($dir) . "/$file" : "/$file";
579 unless (opendir(PARENT, $dotdots))
581 # probably a permissions issue. Try the native command.
582 return File::Spec->rel2abs( $start, _backtick_pwd() );
584 unless (@cst = stat($dotdots))
586 _carp("stat($dotdots): $!");
590 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
598 unless (defined ($dir = readdir(PARENT)))
600 _carp("readdir($dotdots): $!");
604 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
606 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
609 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
611 } while (defined $dir);
612 chop($cwd) unless $cwd eq '/'; # drop the trailing /
619 local $ENV{PWD} = $ENV{PWD} || ''; # Guard against clobberage
622 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
624 # Detaint else we'll explode in taint mode. This is safe because
625 # we're not doing anything dangerous with it.
626 ($path) = $path =~ /(.*)/;
627 ($cwd) = $cwd =~ /(.*)/;
630 _croak("$path: No such file or directory");
634 # Make sure we can be invoked on plain files, not just directories.
636 my ($vol, $dir, $file) = File::Spec->splitpath($path);
637 return File::Spec->catfile($cwd, $path) unless length $dir;
640 my $link_target = readlink($path);
641 die "Can't resolve link $path: $!" unless defined $link_target;
643 $link_target = File::Spec->catpath($vol, $dir, $link_target)
644 unless File::Spec->file_name_is_absolute($link_target);
646 return fast_abs_path($link_target);
649 return $dir eq File::Spec->rootdir
650 ? File::Spec->catpath($vol, $dir, $file)
651 : fast_abs_path(File::Spec->catpath($vol, $dir, '')) . '/' . $file;
654 if (!CORE::chdir($path)) {
655 _croak("Cannot chdir to $path: $!");
657 my $realpath = getcwd();
658 if (! ((-d $cwd) && (CORE::chdir($cwd)))) {
659 _croak("Cannot chdir back to $cwd: $!");
664 # added function alias to follow principle of least surprise
665 # based on previous aliasing. --tchrist 27-Jan-00
666 *fast_realpath = \&fast_abs_path;
669 # --- PORTING SECTION ---
671 # VMS: $ENV{'DEFAULT'} points to default directory at all times
672 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
673 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
674 # in the process logical name table as the default device and directory
675 # seen by Perl. This may not be the same as the default device
676 # and directory seen by DCL after Perl exits, since the effects
677 # the CRTL chdir() function persist only until Perl exits.
680 return $ENV{'DEFAULT'};
684 return $ENV{'DEFAULT'} unless @_;
688 my $unix_rpt = _vms_unix_rpt;
690 if (defined &VMS::Filespec::vmsrealpath) {
694 $path_unix = 1 if ($path =~ m#(?<=\^)/#);
695 $path_unix = 1 if ($path =~ /^\.\.?$/);
696 $path_vms = 1 if ($path =~ m#[\[<\]]#);
697 $path_vms = 1 if ($path =~ /^--?$/);
699 my $unix_mode = $path_unix;
701 # In case of a tie, the Unix report mode decides.
702 if ($path_vms == $path_unix) {
703 $unix_mode = $unix_rpt;
705 $unix_mode = 0 if $path_vms;
711 return VMS::Filespec::unixrealpath($path);
716 my $new_path = VMS::Filespec::vmsrealpath($path);
718 # Perl expects directories to be in directory format
719 $new_path = VMS::Filespec::pathify($new_path) if -d $path;
723 # Fallback to older algorithm if correct ones are not
727 my $link_target = readlink($path);
728 die "Can't resolve link $path: $!" unless defined $link_target;
730 return _vms_abs_path($link_target);
733 # may need to turn foo.dir into [.foo]
734 my $pathified = VMS::Filespec::pathify($path);
735 $path = $pathified if defined $pathified;
737 return VMS::Filespec::rmsexpand($path);
741 $ENV{'PWD'} = `cmd /c cd`;
743 $ENV{'PWD'} =~ s:\\:/:g ;
747 sub _win32_cwd_simple {
750 $ENV{'PWD'} =~ s:\\:/:g ;
755 # Need to avoid taking any sort of reference to the typeglob or the code in
756 # the optree, so that this tests the runtime state of things, as the
757 # ExtUtils::MakeMaker tests for "miniperl" need to be able to fake things at
758 # runtime by deleting the subroutine. *foo{THING} syntax on a symbol table
759 # lookup avoids needing a string eval, which has been reported to cause
760 # problems (for reasons that we haven't been able to get to the bottom of -
761 # rt.cpan.org #56225)
762 if (*{$DynaLoader::{boot_DynaLoader}}{CODE}) {
763 $ENV{'PWD'} = Win32::GetCwd();
766 chomp($ENV{'PWD'} = `cd`);
768 $ENV{'PWD'} =~ s:\\:/:g ;
772 *_NT_cwd = defined &Win32::GetCwd ? \&_win32_cwd : \&_win32_cwd_simple;
775 if (!defined &Dos::GetCwd) {
776 $ENV{'PWD'} = `command /c cd`;
778 $ENV{'PWD'} =~ s:\\:/:g ;
780 $ENV{'PWD'} = Dos::GetCwd();
786 local $ENV{PATH} = '';
787 local $ENV{CDPATH} = '';
788 local $ENV{ENV} = '';
789 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
795 local $ENV{PATH} = '';
796 local $ENV{CDPATH} = '';
797 local $ENV{ENV} = '';
798 my $path = @_ ? shift : '.';
801 defined( open(REALPATH, '-|') || exec '/usr/bin/fullpath', '-t', $path ) or
802 die "Can't open /usr/bin/fullpath: $!";
803 my $realpath = <REALPATH>;
810 $ENV{'PWD'} = EPOC::getcwd();
815 # Now that all the base-level functions are set up, alias the
816 # user-level functions to the right places
818 if (exists $METHOD_MAP{$^O}) {
819 my $map = $METHOD_MAP{$^O};
820 foreach my $name (keys %$map) {
821 local $^W = 0; # assignments trigger 'subroutine redefined' warning
823 *{$name} = \&{$map->{$name}};
827 # In case the XS version doesn't load.
828 *abs_path = \&_perl_abs_path unless defined &abs_path;
829 *getcwd = \&_perl_getcwd unless defined &getcwd;
831 # added function alias for those of us more
832 # used to the libc function. --tchrist 27-Jan-00
833 *realpath = \&abs_path;