6 Cwd - get pathname of current working directory
14 my $abs_path = abs_path($file);
18 This module provides functions for determining the pathname of the
19 current working directory. It is recommended that getcwd (or another
20 *cwd() function) be used in I<all> code to ensure portability.
22 By default, it exports the functions cwd(), getcwd(), fastcwd(), and
23 fastgetcwd() into the caller's namespace.
26 =head2 getcwd and friends
28 Each of these functions are called without arguments and return the
29 absolute path of the current working directory.
37 Returns the current working directory.
39 Re-implements the getcwd(3) (or getwd(3)) functions in Perl.
47 The cwd() is the most natural form for the current architecture. For
48 most systems it is identical to `pwd` (but without the trailing line
57 A more dangerous version of getcwd(), but potentially faster.
59 It might conceivably chdir() you out of a directory that it can't
60 chdir() you back into. If fastcwd encounters a problem it will return
61 undef but will probably leave you in a different directory. For a
62 measure of extra security, if everything appears to have worked, the
63 fastcwd() function will check that it leaves you in the same directory
64 that it started in. If it has changed it will C<die> with the message
65 "Unstable directory path, current directory changed
66 unexpectedly". That should never happen.
70 my $cwd = fastgetcwd();
72 The fastgetcwd() function is provided as a synonym for cwd().
77 =head2 abs_path and friends
79 These functions are exported only on request. They each take a single
80 argument and return the absolute pathname for it.
86 my $abs_path = abs_path($file);
88 Uses the same algorithm as getcwd(). Symbolic links and relative-path
89 components ("." and "..") are resolved to return the canonical
90 pathname, just like realpath(3).
96 my $abs_path = realpath($file);
98 A synonym for abs_path().
104 my $abs_path = fast_abs_path($file);
106 A more dangerous, but potentially faster version of abs_path.
108 This function is B<Not> taint-safe : you can't use it in programs
109 that work under taint mode.
115 If you ask to override your chdir() built-in function,
119 then your PWD environment variable will be kept up to date. Note that
120 it will only be kept up to date if all packages which use chdir import
130 Since the path seperators are different on some operating systems ('/'
131 on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
132 modules wherever portability is a concern.
136 Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
137 functions are all aliases for the C<cwd()> function, which, on Mac OS,
138 calls `pwd`. Likewise, the C<abs_path()> function is an alias for
153 our $VERSION = '2.06';
155 use base qw/ Exporter /;
156 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
157 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
159 # sys_cwd may keep the builtin command
161 # All the functionality of this module may provided by builtins,
162 # there is no sense to process the rest of the file.
163 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
165 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
171 *abs_path = \&sys_abspath;
172 *fast_abs_path = \&abs_path;
173 *realpath = \&abs_path;
174 *fast_realpath = \&abs_path;
180 undef *Cwd::fastcwd; # avoid redefinition warning
181 XSLoader::load('Cwd');
185 # Find the pwd command in the expected locations. We assume these
186 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
187 # so everything works under taint mode.
189 foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
197 # The 'natural and safe form' for UNIX (pwd may be setuid root)
203 local $ENV{BASH_ENV};
204 my $cwd = `$pwd_cmd`;
205 # Belt-and-suspenders in case someone said "undef $/".
207 # `pwd` may fail e.g. if the disk is full
208 chomp($cwd) if defined $cwd;
212 # Since some ports may predefine cwd internally (e.g., NT)
213 # we take care not to override an existing definition for cwd().
215 unless(defined &cwd) {
216 # The pwd command is not available in some chroot(2)'ed environments
217 if( $^O eq 'MacOS' || (defined $ENV{PATH} &&
218 grep { -x "$_/pwd" } split(':', $ENV{PATH})) )
220 *cwd = \&_backtick_pwd;
227 # set a reasonable (and very safe) default for fastgetcwd, in case it
228 # isn't redefined later (20001212 rspier)
231 # By Brandon S. Allbery
233 # Usage: $cwd = getcwd();
243 # Usage: $cwd = &fastcwd;
245 # This is a faster version of getcwd. It's also more dangerous because
246 # you might chdir out of a directory that you can't chdir back into.
249 my($odev, $oino, $cdev, $cino, $tdev, $tino);
253 my($orig_cdev, $orig_cino) = stat('.');
254 ($cdev, $cino) = ($orig_cdev, $orig_cino);
257 ($odev, $oino) = ($cdev, $cino);
258 CORE::chdir('..') || return undef;
259 ($cdev, $cino) = stat('.');
260 last if $odev == $cdev && $oino == $cino;
261 opendir(DIR, '.') || return undef;
263 $direntry = readdir(DIR);
264 last unless defined $direntry;
265 next if $direntry eq '.';
266 next if $direntry eq '..';
268 ($tdev, $tino) = lstat($direntry);
269 last unless $tdev != $odev || $tino != $oino;
272 return undef unless defined $direntry; # should never happen
273 unshift(@path, $direntry);
275 $path = '/' . join('/', @path);
276 if ($^O eq 'apollo') { $path = "/".$path; }
277 # At this point $path may be tainted (if tainting) and chdir would fail.
278 # Untaint it then check that we landed where we started.
279 $path =~ /^(.*)\z/s # untaint
280 && CORE::chdir($1) or return undef;
281 ($cdev, $cino) = stat('.');
282 die "Unstable directory path, current directory changed unexpectedly"
283 if $cdev != $orig_cdev || $cino != $orig_cino;
288 # Keeps track of current working directory in PWD environment var
296 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
297 my($dd,$di) = stat('.');
298 my($pd,$pi) = stat($ENV{'PWD'});
299 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
305 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
308 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
309 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
310 my($pd,$pi) = stat($2);
311 my($dd,$di) = stat($1);
312 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
320 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
321 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
322 chdir_init() unless $chdir_init;
324 if ($^O eq 'MSWin32') {
325 # get the full path name *before* the chdir()
326 $newpwd = Win32::GetFullPathName($newdir);
329 return 0 unless CORE::chdir $newdir;
332 return $ENV{'PWD'} = $ENV{'DEFAULT'}
334 elsif ($^O eq 'MacOS') {
335 return $ENV{'PWD'} = cwd();
337 elsif ($^O eq 'MSWin32') {
338 $ENV{'PWD'} = $newpwd;
342 if ($newdir =~ m#^/#s) {
343 $ENV{'PWD'} = $newdir;
345 my @curdir = split(m#/#,$ENV{'PWD'});
346 @curdir = ('') unless @curdir;
348 foreach $component (split(m#/#, $newdir)) {
349 next if $component eq '.';
350 pop(@curdir),next if $component eq '..';
351 push(@curdir,$component);
353 $ENV{'PWD'} = join('/',@curdir) || '/';
359 # In case the XS version doesn't load.
360 *abs_path = \&_perl_abs_path unless defined &abs_path;
363 my $start = @_ ? shift : '.';
364 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
366 unless (@cst = stat( $start ))
368 carp "stat($start): $!";
377 unless (opendir(PARENT, $dotdots))
379 carp "opendir($dotdots): $!";
382 unless (@cst = stat($dotdots))
384 carp "stat($dotdots): $!";
388 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
396 unless (defined ($dir = readdir(PARENT)))
398 carp "readdir($dotdots): $!";
402 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
404 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
407 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
409 } while (defined $dir);
410 chop($cwd) unless $cwd eq '/'; # drop the trailing /
415 # added function alias for those of us more
416 # used to the libc function. --tchrist 27-Jan-00
417 *realpath = \&abs_path;
422 my $path = @_ ? shift : File::Spec->curdir;
423 CORE::chdir($path) || croak "Cannot chdir to $path: $!";
424 my $realpath = getcwd();
425 -d $cwd && CORE::chdir($cwd) ||
426 croak "Cannot chdir back to $cwd: $!";
430 # added function alias to follow principle of least surprise
431 # based on previous aliasing. --tchrist 27-Jan-00
432 *fast_realpath = \&fast_abs_path;
435 # --- PORTING SECTION ---
437 # VMS: $ENV{'DEFAULT'} points to default directory at all times
438 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
439 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
440 # in the process logical name table as the default device and directory
441 # seen by Perl. This may not be the same as the default device
442 # and directory seen by DCL after Perl exits, since the effects
443 # the CRTL chdir() function persist only until Perl exits.
446 return $ENV{'DEFAULT'};
450 return $ENV{'DEFAULT'} unless @_;
451 my $path = VMS::Filespec::pathify($_[0]);
452 croak("Invalid path name $_[0]") unless defined $path;
453 return VMS::Filespec::rmsexpand($path);
457 $ENV{'PWD'} = `cmd /c cd`;
459 $ENV{'PWD'} =~ s:\\:/:g ;
464 $ENV{'PWD'} = Win32::GetCwd();
465 $ENV{'PWD'} =~ s:\\:/:g ;
469 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
470 defined &Win32::GetCwd);
472 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
475 if (!defined &Dos::GetCwd) {
476 $ENV{'PWD'} = `command /c cd`;
478 $ENV{'PWD'} =~ s:\\:/:g ;
480 $ENV{'PWD'} = Dos::GetCwd();
486 local $ENV{PATH} = '';
487 local $ENV{CDPATH} = '';
488 local $ENV{ENV} = '';
489 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
495 local $ENV{PATH} = '';
496 local $ENV{CDPATH} = '';
497 local $ENV{ENV} = '';
498 my $path = @_ ? shift : '.';
499 my $realpath=`/usr/bin/fullpath -t $path`;
505 $ENV{'PWD'} = EPOC::getcwd();
510 no warnings; # assignments trigger 'subroutine redefined' warning
514 *getcwd = \&_vms_cwd;
515 *fastcwd = \&_vms_cwd;
516 *fastgetcwd = \&_vms_cwd;
517 *abs_path = \&_vms_abs_path;
518 *fast_abs_path = \&_vms_abs_path;
520 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
521 # We assume that &_NT_cwd is defined as an XSUB or in the core.
524 *fastcwd = \&_NT_cwd;
525 *fastgetcwd = \&_NT_cwd;
526 *abs_path = \&fast_abs_path;
527 *realpath = \&fast_abs_path;
529 elsif ($^O eq 'os2') {
530 # sys_cwd may keep the builtin command
531 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
535 *abs_path = \&fast_abs_path;
537 elsif ($^O eq 'dos') {
539 *getcwd = \&_dos_cwd;
540 *fastgetcwd = \&_dos_cwd;
541 *fastcwd = \&_dos_cwd;
542 *abs_path = \&fast_abs_path;
544 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
546 *getcwd = \&_qnx_cwd;
547 *fastgetcwd = \&_qnx_cwd;
548 *fastcwd = \&_qnx_cwd;
549 *abs_path = \&_qnx_abs_path;
550 *fast_abs_path = \&_qnx_abs_path;
552 elsif ($^O eq 'cygwin') {
556 *abs_path = \&fast_abs_path;
558 elsif ($^O eq 'epoc') {
560 *getcwd = \&_epoc_cwd;
561 *fastgetcwd = \&_epoc_cwd;
562 *fastcwd = \&_epoc_cwd;
563 *abs_path = \&fast_abs_path;
565 elsif ($^O eq 'MacOS') {
569 *abs_path = \&fast_abs_path;