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 # set a reasonable (and very safe) default for fastgetcwd, in case it
361 # isn't redefined later (20001212 rspier)
364 # By Brandon S. Allbery
366 # Usage: $cwd = getcwd();
375 # Usage: $cwd = &fastcwd;
377 # This is a faster version of getcwd. It's also more dangerous because
378 # you might chdir out of a directory that you can't chdir back into.
381 my($odev, $oino, $cdev, $cino, $tdev, $tino);
385 my($orig_cdev, $orig_cino) = stat('.');
386 ($cdev, $cino) = ($orig_cdev, $orig_cino);
389 ($odev, $oino) = ($cdev, $cino);
390 CORE::chdir('..') || return undef;
391 ($cdev, $cino) = stat('.');
392 last if $odev == $cdev && $oino == $cino;
393 opendir(DIR, '.') || return undef;
395 $direntry = readdir(DIR);
396 last unless defined $direntry;
397 next if $direntry eq '.';
398 next if $direntry eq '..';
400 ($tdev, $tino) = lstat($direntry);
401 last unless $tdev != $odev || $tino != $oino;
404 return undef unless defined $direntry; # should never happen
405 unshift(@path, $direntry);
407 $path = '/' . join('/', @path);
408 if ($^O eq 'apollo') { $path = "/".$path; }
409 # At this point $path may be tainted (if tainting) and chdir would fail.
410 # Untaint it then check that we landed where we started.
411 $path =~ /^(.*)\z/s # untaint
412 && CORE::chdir($1) or return undef;
413 ($cdev, $cino) = stat('.');
414 die "Unstable directory path, current directory changed unexpectedly"
415 if $cdev != $orig_cdev || $cino != $orig_cino;
418 if (not defined &fastcwd) { *fastcwd = \&fastcwd_ }
421 # Keeps track of current working directory in PWD environment var
429 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
430 my($dd,$di) = stat('.');
431 my($pd,$pi) = stat($ENV{'PWD'});
432 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
438 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
441 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
442 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
443 my($pd,$pi) = stat($2);
444 my($dd,$di) = stat($1);
445 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
453 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
454 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
455 chdir_init() unless $chdir_init;
457 if ($^O eq 'MSWin32') {
458 # get the full path name *before* the chdir()
459 $newpwd = Win32::GetFullPathName($newdir);
462 return 0 unless CORE::chdir $newdir;
465 return $ENV{'PWD'} = $ENV{'DEFAULT'}
467 elsif ($^O eq 'MacOS') {
468 return $ENV{'PWD'} = cwd();
470 elsif ($^O eq 'MSWin32') {
471 $ENV{'PWD'} = $newpwd;
475 if ($newdir =~ m#^/#s) {
476 $ENV{'PWD'} = $newdir;
478 my @curdir = split(m#/#,$ENV{'PWD'});
479 @curdir = ('') unless @curdir;
481 foreach $component (split(m#/#, $newdir)) {
482 next if $component eq '.';
483 pop(@curdir),next if $component eq '..';
484 push(@curdir,$component);
486 $ENV{'PWD'} = join('/',@curdir) || '/';
494 my $start = @_ ? shift : '.';
495 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
497 unless (@cst = stat( $start ))
499 _carp("stat($start): $!");
504 # Make sure we can be invoked on plain files, not just directories.
505 # NOTE that this routine assumes that '/' is the only directory separator.
507 my ($dir, $file) = $start =~ m{^(.*)/(.+)$}
508 or return cwd() . '/' . $start;
510 # Can't use "-l _" here, because the previous stat was a stat(), not an lstat().
512 my $link_target = readlink($start);
513 die "Can't resolve link $start: $!" unless defined $link_target;
516 $link_target = $dir . '/' . $link_target
517 unless File::Spec->file_name_is_absolute($link_target);
519 return abs_path($link_target);
522 return $dir ? abs_path($dir) . "/$file" : "/$file";
532 unless (opendir(PARENT, $dotdots))
534 _carp("opendir($dotdots): $!");
537 unless (@cst = stat($dotdots))
539 _carp("stat($dotdots): $!");
543 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
551 unless (defined ($dir = readdir(PARENT)))
553 _carp("readdir($dotdots): $!");
557 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
559 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
562 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
564 } while (defined $dir);
565 chop($cwd) unless $cwd eq '/'; # drop the trailing /
572 local $ENV{PWD} = $ENV{PWD} || ''; # Guard against clobberage
575 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
577 # Detaint else we'll explode in taint mode. This is safe because
578 # we're not doing anything dangerous with it.
579 ($path) = $path =~ /(.*)/;
580 ($cwd) = $cwd =~ /(.*)/;
583 _croak("$path: No such file or directory");
587 # Make sure we can be invoked on plain files, not just directories.
589 my ($vol, $dir, $file) = File::Spec->splitpath($path);
590 return File::Spec->catfile($cwd, $path) unless length $dir;
593 my $link_target = readlink($path);
594 die "Can't resolve link $path: $!" unless defined $link_target;
596 $link_target = File::Spec->catpath($vol, $dir, $link_target)
597 unless File::Spec->file_name_is_absolute($link_target);
599 return fast_abs_path($link_target);
602 return $dir eq File::Spec->rootdir
603 ? File::Spec->catpath($vol, $dir, $file)
604 : fast_abs_path(File::Spec->catpath($vol, $dir, '')) . '/' . $file;
607 if (!CORE::chdir($path)) {
608 _croak("Cannot chdir to $path: $!");
610 my $realpath = getcwd();
611 if (! ((-d $cwd) && (CORE::chdir($cwd)))) {
612 _croak("Cannot chdir back to $cwd: $!");
617 # added function alias to follow principle of least surprise
618 # based on previous aliasing. --tchrist 27-Jan-00
619 *fast_realpath = \&fast_abs_path;
622 # --- PORTING SECTION ---
624 # VMS: $ENV{'DEFAULT'} points to default directory at all times
625 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
626 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
627 # in the process logical name table as the default device and directory
628 # seen by Perl. This may not be the same as the default device
629 # and directory seen by DCL after Perl exits, since the effects
630 # the CRTL chdir() function persist only until Perl exits.
633 return $ENV{'DEFAULT'};
637 return $ENV{'DEFAULT'} unless @_;
639 # may need to turn foo.dir into [.foo]
640 my $path = VMS::Filespec::pathify($_[0]);
641 $path = $_[0] unless defined $path;
643 return VMS::Filespec::rmsexpand($path);
647 $ENV{'PWD'} = `cmd /c cd`;
649 $ENV{'PWD'} =~ s:\\:/:g ;
654 $ENV{'PWD'} = Win32::GetCwd();
655 $ENV{'PWD'} =~ s:\\:/:g ;
659 *_NT_cwd = defined &Win32::GetCwd ? \&_win32_cwd : \&_os2_cwd;
662 if (!defined &Dos::GetCwd) {
663 $ENV{'PWD'} = `command /c cd`;
665 $ENV{'PWD'} =~ s:\\:/:g ;
667 $ENV{'PWD'} = Dos::GetCwd();
673 local $ENV{PATH} = '';
674 local $ENV{CDPATH} = '';
675 local $ENV{ENV} = '';
676 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
682 local $ENV{PATH} = '';
683 local $ENV{CDPATH} = '';
684 local $ENV{ENV} = '';
685 my $path = @_ ? shift : '.';
688 defined( open(REALPATH, '-|') || exec '/usr/bin/fullpath', '-t', $path ) or
689 die "Can't open /usr/bin/fullpath: $!";
690 my $realpath = <REALPATH>;
697 $ENV{'PWD'} = EPOC::getcwd();
702 # Now that all the base-level functions are set up, alias the
703 # user-level functions to the right places
705 if (exists $METHOD_MAP{$^O}) {
706 my $map = $METHOD_MAP{$^O};
707 foreach my $name (keys %$map) {
708 local $^W = 0; # assignments trigger 'subroutine redefined' warning
710 *{$name} = \&{$map->{$name}};
714 # In case the XS version doesn't load.
715 *abs_path = \&_perl_abs_path unless defined &abs_path;
716 *getcwd = \&_perl_getcwd unless defined &getcwd;
718 # added function alias for those of us more
719 # used to the libc function. --tchrist 27-Jan-00
720 *realpath = \&abs_path;