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);
176 @ISA = qw/ Exporter /;
177 @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
178 push @EXPORT, qw(getdcwd) if $^O eq 'MSWin32';
179 @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
181 # sys_cwd may keep the builtin command
183 # All the functionality of this module may provided by builtins,
184 # there is no sense to process the rest of the file.
185 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
190 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
195 *fast_abs_path = \&sys_abspath if defined &sys_abspath;
196 *abs_path = \&fast_abs_path;
197 *realpath = \&fast_abs_path;
198 *fast_realpath = \&fast_abs_path;
203 # If loading the XS stuff doesn't work, we can fall back to pure perl
207 XSLoader::load( __PACKAGE__, $VERSION );
210 push @ISA, 'DynaLoader';
211 __PACKAGE__->bootstrap( $VERSION );
215 # Must be after the DynaLoader stuff:
216 $VERSION = eval $VERSION;
218 # Big nasty table of function aliases
224 getcwd => '_vms_cwd',
225 fastcwd => '_vms_cwd',
226 fastgetcwd => '_vms_cwd',
227 abs_path => '_vms_abs_path',
228 fast_abs_path => '_vms_abs_path',
233 # We assume that &_NT_cwd is defined as an XSUB or in the core.
236 fastcwd => '_NT_cwd',
237 fastgetcwd => '_NT_cwd',
238 abs_path => 'fast_abs_path',
239 realpath => 'fast_abs_path',
245 getcwd => '_dos_cwd',
246 fastgetcwd => '_dos_cwd',
247 fastcwd => '_dos_cwd',
248 abs_path => 'fast_abs_path',
254 getcwd => '_qnx_cwd',
255 fastgetcwd => '_qnx_cwd',
256 fastcwd => '_qnx_cwd',
257 abs_path => '_qnx_abs_path',
258 fast_abs_path => '_qnx_abs_path',
266 abs_path => 'fast_abs_path',
267 realpath => 'fast_abs_path',
273 getcwd => '_epoc_cwd',
274 fastgetcwd => '_epoc_cwd',
275 fastcwd => '_epoc_cwd',
276 abs_path => 'fast_abs_path',
284 abs_path => 'fast_abs_path',
288 $METHOD_MAP{NT} = $METHOD_MAP{MSWin32};
289 $METHOD_MAP{nto} = $METHOD_MAP{qnx};
292 # Find the pwd command in the expected locations. We assume these
293 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
294 # so everything works under taint mode.
296 foreach my $try ('/bin/pwd',
298 '/QOpenSys/bin/pwd', # OS/400 PASE.
306 my $found_pwd_cmd = defined($pwd_cmd);
308 # Isn't this wrong? _backtick_pwd() will fail if somenone has
309 # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
310 # See [perl #16774]. --jhi
315 sub _carp { require Carp; Carp::carp(@_) }
316 sub _croak { require Carp; Carp::croak(@_) }
318 # The 'natural and safe form' for UNIX (pwd may be setuid root)
320 # Localize %ENV entries in a way that won't create new hash keys
321 my @localize = grep exists $ENV{$_}, qw(PATH IFS CDPATH ENV BASH_ENV);
322 local @ENV{@localize};
324 my $cwd = `$pwd_cmd`;
325 # Belt-and-suspenders in case someone said "undef $/".
327 # `pwd` may fail e.g. if the disk is full
328 chomp($cwd) if defined $cwd;
332 # Since some ports may predefine cwd internally (e.g., NT)
333 # we take care not to override an existing definition for cwd().
335 unless ($METHOD_MAP{$^O}{cwd} or defined &cwd) {
336 # The pwd command is not available in some chroot(2)'ed environments
337 my $sep = $Config::Config{path_sep} || ':';
338 my $os = $^O; # Protect $^O from tainting
341 # Try again to find a pwd, this time searching the whole PATH.
342 if (defined $ENV{PATH} and $os ne 'MSWin32') { # no pwd on Windows
343 my @candidates = split($sep, $ENV{PATH});
344 while (!$found_pwd_cmd and @candidates) {
345 my $candidate = shift @candidates;
346 $found_pwd_cmd = 1 if -x "$candidate/pwd";
350 # MacOS has some special magic to make `pwd` work.
351 if( $os eq 'MacOS' || $found_pwd_cmd )
353 *cwd = \&_backtick_pwd;
360 if ($^O eq 'cygwin') {
361 # We need to make sure cwd() is called with no args, because it's
362 # got an arg-less prototype and will die if args are present.
364 my $orig_cwd = \&cwd;
365 *cwd = sub { &$orig_cwd() }
369 # set a reasonable (and very safe) default for fastgetcwd, in case it
370 # isn't redefined later (20001212 rspier)
373 # A non-XS version of getcwd() - also used to bootstrap the perl build
374 # process, when miniperl is running and no XS loading happens.
382 # Usage: $cwd = &fastcwd;
384 # This is a faster version of getcwd. It's also more dangerous because
385 # you might chdir out of a directory that you can't chdir back into.
388 my($odev, $oino, $cdev, $cino, $tdev, $tino);
392 my($orig_cdev, $orig_cino) = stat('.');
393 ($cdev, $cino) = ($orig_cdev, $orig_cino);
396 ($odev, $oino) = ($cdev, $cino);
397 CORE::chdir('..') || return undef;
398 ($cdev, $cino) = stat('.');
399 last if $odev == $cdev && $oino == $cino;
400 opendir(DIR, '.') || return undef;
402 $direntry = readdir(DIR);
403 last unless defined $direntry;
404 next if $direntry eq '.';
405 next if $direntry eq '..';
407 ($tdev, $tino) = lstat($direntry);
408 last unless $tdev != $odev || $tino != $oino;
411 return undef unless defined $direntry; # should never happen
412 unshift(@path, $direntry);
414 $path = '/' . join('/', @path);
415 if ($^O eq 'apollo') { $path = "/".$path; }
416 # At this point $path may be tainted (if tainting) and chdir would fail.
417 # Untaint it then check that we landed where we started.
418 $path =~ /^(.*)\z/s # untaint
419 && CORE::chdir($1) or return undef;
420 ($cdev, $cino) = stat('.');
421 die "Unstable directory path, current directory changed unexpectedly"
422 if $cdev != $orig_cdev || $cino != $orig_cino;
425 if (not defined &fastcwd) { *fastcwd = \&fastcwd_ }
428 # Keeps track of current working directory in PWD environment var
436 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
437 my($dd,$di) = stat('.');
438 my($pd,$pi) = stat($ENV{'PWD'});
439 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
445 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
448 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
449 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
450 my($pd,$pi) = stat($2);
451 my($dd,$di) = stat($1);
452 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
460 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
461 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
462 chdir_init() unless $chdir_init;
464 if ($^O eq 'MSWin32') {
465 # get the full path name *before* the chdir()
466 $newpwd = Win32::GetFullPathName($newdir);
469 return 0 unless CORE::chdir $newdir;
472 return $ENV{'PWD'} = $ENV{'DEFAULT'}
474 elsif ($^O eq 'MacOS') {
475 return $ENV{'PWD'} = cwd();
477 elsif ($^O eq 'MSWin32') {
478 $ENV{'PWD'} = $newpwd;
482 if (ref $newdir eq 'GLOB') { # in case a file/dir handle is passed in
484 } elsif ($newdir =~ m#^/#s) {
485 $ENV{'PWD'} = $newdir;
487 my @curdir = split(m#/#,$ENV{'PWD'});
488 @curdir = ('') unless @curdir;
490 foreach $component (split(m#/#, $newdir)) {
491 next if $component eq '.';
492 pop(@curdir),next if $component eq '..';
493 push(@curdir,$component);
495 $ENV{'PWD'} = join('/',@curdir) || '/';
503 my $start = @_ ? shift : '.';
504 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
506 unless (@cst = stat( $start ))
508 _carp("stat($start): $!");
513 # Make sure we can be invoked on plain files, not just directories.
514 # NOTE that this routine assumes that '/' is the only directory separator.
516 my ($dir, $file) = $start =~ m{^(.*)/(.+)$}
517 or return cwd() . '/' . $start;
519 # Can't use "-l _" here, because the previous stat was a stat(), not an lstat().
521 my $link_target = readlink($start);
522 die "Can't resolve link $start: $!" unless defined $link_target;
525 $link_target = $dir . '/' . $link_target
526 unless File::Spec->file_name_is_absolute($link_target);
528 return abs_path($link_target);
531 return $dir ? abs_path($dir) . "/$file" : "/$file";
541 unless (opendir(PARENT, $dotdots))
543 # probably a permissions issue. Try the native command.
544 return File::Spec->rel2abs( $start, _backtick_pwd() );
546 unless (@cst = stat($dotdots))
548 _carp("stat($dotdots): $!");
552 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
560 unless (defined ($dir = readdir(PARENT)))
562 _carp("readdir($dotdots): $!");
566 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
568 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
571 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
573 } while (defined $dir);
574 chop($cwd) unless $cwd eq '/'; # drop the trailing /
581 local $ENV{PWD} = $ENV{PWD} || ''; # Guard against clobberage
584 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
586 # Detaint else we'll explode in taint mode. This is safe because
587 # we're not doing anything dangerous with it.
588 ($path) = $path =~ /(.*)/;
589 ($cwd) = $cwd =~ /(.*)/;
592 _croak("$path: No such file or directory");
596 # Make sure we can be invoked on plain files, not just directories.
598 my ($vol, $dir, $file) = File::Spec->splitpath($path);
599 return File::Spec->catfile($cwd, $path) unless length $dir;
602 my $link_target = readlink($path);
603 die "Can't resolve link $path: $!" unless defined $link_target;
605 $link_target = File::Spec->catpath($vol, $dir, $link_target)
606 unless File::Spec->file_name_is_absolute($link_target);
608 return fast_abs_path($link_target);
611 return $dir eq File::Spec->rootdir
612 ? File::Spec->catpath($vol, $dir, $file)
613 : fast_abs_path(File::Spec->catpath($vol, $dir, '')) . '/' . $file;
616 if (!CORE::chdir($path)) {
617 _croak("Cannot chdir to $path: $!");
619 my $realpath = getcwd();
620 if (! ((-d $cwd) && (CORE::chdir($cwd)))) {
621 _croak("Cannot chdir back to $cwd: $!");
626 # added function alias to follow principle of least surprise
627 # based on previous aliasing. --tchrist 27-Jan-00
628 *fast_realpath = \&fast_abs_path;
631 # --- PORTING SECTION ---
633 # VMS: $ENV{'DEFAULT'} points to default directory at all times
634 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
635 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
636 # in the process logical name table as the default device and directory
637 # seen by Perl. This may not be the same as the default device
638 # and directory seen by DCL after Perl exits, since the effects
639 # the CRTL chdir() function persist only until Perl exits.
642 return $ENV{'DEFAULT'};
646 return $ENV{'DEFAULT'} unless @_;
650 my $link_target = readlink($path);
651 die "Can't resolve link $path: $!" unless defined $link_target;
653 return _vms_abs_path($link_target);
656 if (defined &VMS::Filespec::vms_realpath) {
658 if ($path =~ m#(?<=\^)/# ) {
660 return VMS::Filespec::vms_realpath($path);
665 my $new_path = VMS::Filespec::vms_realname($path);
667 # Perl expects directories to be in directory format
668 $new_path = VMS::Filespec::pathify($new_path) if -d $path;
672 # Fallback to older algorithm if correct ones are not
675 # may need to turn foo.dir into [.foo]
676 my $pathified = VMS::Filespec::pathify($path);
677 $path = $pathified if defined $pathified;
679 return VMS::Filespec::rmsexpand($path);
683 $ENV{'PWD'} = `cmd /c cd`;
685 $ENV{'PWD'} =~ s:\\:/:g ;
690 if (defined &DynaLoader::boot_DynaLoader) {
691 $ENV{'PWD'} = Win32::GetCwd();
694 chomp($ENV{'PWD'} = `cd`);
696 $ENV{'PWD'} =~ s:\\:/:g ;
700 *_NT_cwd = defined &Win32::GetCwd ? \&_win32_cwd : \&_os2_cwd;
703 if (!defined &Dos::GetCwd) {
704 $ENV{'PWD'} = `command /c cd`;
706 $ENV{'PWD'} =~ s:\\:/:g ;
708 $ENV{'PWD'} = Dos::GetCwd();
714 local $ENV{PATH} = '';
715 local $ENV{CDPATH} = '';
716 local $ENV{ENV} = '';
717 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
723 local $ENV{PATH} = '';
724 local $ENV{CDPATH} = '';
725 local $ENV{ENV} = '';
726 my $path = @_ ? shift : '.';
729 defined( open(REALPATH, '-|') || exec '/usr/bin/fullpath', '-t', $path ) or
730 die "Can't open /usr/bin/fullpath: $!";
731 my $realpath = <REALPATH>;
738 $ENV{'PWD'} = EPOC::getcwd();
743 # Now that all the base-level functions are set up, alias the
744 # user-level functions to the right places
746 if (exists $METHOD_MAP{$^O}) {
747 my $map = $METHOD_MAP{$^O};
748 foreach my $name (keys %$map) {
749 local $^W = 0; # assignments trigger 'subroutine redefined' warning
751 *{$name} = \&{$map->{$name}};
755 # In case the XS version doesn't load.
756 *abs_path = \&_perl_abs_path unless defined &abs_path;
757 *getcwd = \&_perl_getcwd unless defined &getcwd;
759 # added function alias for those of us more
760 # used to the libc function. --tchrist 27-Jan-00
761 *realpath = \&abs_path;