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
51 Unfortunately, cwd() is B<not> taint-safe.
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.
114 If you ask to override your chdir() built-in function,
118 then your PWD environment variable will be kept up to date. Note that
119 it will only be kept up to date if all packages which use chdir import
129 Since the path seperators are different on some operating systems ('/'
130 on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
131 modules wherever portability is a concern.
135 Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
136 functions are all aliases for the C<cwd()> function, which, on Mac OS,
137 calls `pwd`. Likewise, the C<abs_path()> function is an alias for
152 our $VERSION = '2.06';
154 use base qw/ Exporter /;
155 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
156 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
158 # sys_cwd may keep the builtin command
160 # All the functionality of this module may provided by builtins,
161 # there is no sense to process the rest of the file.
162 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
164 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
170 *abs_path = \&sys_abspath;
171 *fast_abs_path = \&abs_path;
172 *realpath = \&abs_path;
173 *fast_realpath = \&abs_path;
179 undef *Cwd::fastcwd; # avoid redefinition warning
180 XSLoader::load('Cwd');
184 # Find the pwd command in the expected locations. We assume these
185 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
186 # so everything works under taint mode.
188 foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
196 # The 'natural and safe form' for UNIX (pwd may be setuid root)
198 local @ENV{qw(PATH IFS CDPATH ENV BASH_ENV)};
199 my $cwd = `$pwd_cmd`;
200 # Belt-and-suspenders in case someone said "undef $/".
202 # `pwd` may fail e.g. if the disk is full
203 chomp($cwd) if defined $cwd;
207 # Since some ports may predefine cwd internally (e.g., NT)
208 # we take care not to override an existing definition for cwd().
210 unless(defined &cwd) {
211 # The pwd command is not available in some chroot(2)'ed environments
212 if( $^O eq 'MacOS' || (defined $ENV{PATH} &&
213 grep { -x "$_/pwd" } split(':', $ENV{PATH})) )
215 *cwd = \&_backtick_pwd;
222 # set a reasonable (and very safe) default for fastgetcwd, in case it
223 # isn't redefined later (20001212 rspier)
226 # By Brandon S. Allbery
228 # Usage: $cwd = getcwd();
238 # Usage: $cwd = &fastcwd;
240 # This is a faster version of getcwd. It's also more dangerous because
241 # you might chdir out of a directory that you can't chdir back into.
244 my($odev, $oino, $cdev, $cino, $tdev, $tino);
248 my($orig_cdev, $orig_cino) = stat('.');
249 ($cdev, $cino) = ($orig_cdev, $orig_cino);
252 ($odev, $oino) = ($cdev, $cino);
253 CORE::chdir('..') || return undef;
254 ($cdev, $cino) = stat('.');
255 last if $odev == $cdev && $oino == $cino;
256 opendir(DIR, '.') || return undef;
258 $direntry = readdir(DIR);
259 last unless defined $direntry;
260 next if $direntry eq '.';
261 next if $direntry eq '..';
263 ($tdev, $tino) = lstat($direntry);
264 last unless $tdev != $odev || $tino != $oino;
267 return undef unless defined $direntry; # should never happen
268 unshift(@path, $direntry);
270 $path = '/' . join('/', @path);
271 if ($^O eq 'apollo') { $path = "/".$path; }
272 # At this point $path may be tainted (if tainting) and chdir would fail.
273 # To be more useful we untaint it then check that we landed where we started.
274 $path = $1 if $path =~ /^(.*)\z/s; # untaint
275 CORE::chdir($path) || return undef;
276 ($cdev, $cino) = stat('.');
277 die "Unstable directory path, current directory changed unexpectedly"
278 if $cdev != $orig_cdev || $cino != $orig_cino;
283 # Keeps track of current working directory in PWD environment var
291 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
292 my($dd,$di) = stat('.');
293 my($pd,$pi) = stat($ENV{'PWD'});
294 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
300 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
303 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
304 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
305 my($pd,$pi) = stat($2);
306 my($dd,$di) = stat($1);
307 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
315 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
316 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
317 chdir_init() unless $chdir_init;
319 if ($^O eq 'MSWin32') {
320 # get the full path name *before* the chdir()
321 $newpwd = Win32::GetFullPathName($newdir);
324 return 0 unless CORE::chdir $newdir;
327 return $ENV{'PWD'} = $ENV{'DEFAULT'}
329 elsif ($^O eq 'MacOS') {
330 return $ENV{'PWD'} = cwd();
332 elsif ($^O eq 'MSWin32') {
333 $ENV{'PWD'} = $newpwd;
337 if ($newdir =~ m#^/#s) {
338 $ENV{'PWD'} = $newdir;
340 my @curdir = split(m#/#,$ENV{'PWD'});
341 @curdir = ('') unless @curdir;
343 foreach $component (split(m#/#, $newdir)) {
344 next if $component eq '.';
345 pop(@curdir),next if $component eq '..';
346 push(@curdir,$component);
348 $ENV{'PWD'} = join('/',@curdir) || '/';
354 # In case the XS version doesn't load.
355 *abs_path = \&_perl_abs_path unless defined &abs_path;
358 my $start = @_ ? shift : '.';
359 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
361 unless (@cst = stat( $start ))
363 carp "stat($start): $!";
372 unless (opendir(PARENT, $dotdots))
374 carp "opendir($dotdots): $!";
377 unless (@cst = stat($dotdots))
379 carp "stat($dotdots): $!";
383 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
391 unless (defined ($dir = readdir(PARENT)))
393 carp "readdir($dotdots): $!";
397 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
399 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
402 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
404 } while (defined $dir);
405 chop($cwd) unless $cwd eq '/'; # drop the trailing /
410 # added function alias for those of us more
411 # used to the libc function. --tchrist 27-Jan-00
412 *realpath = \&abs_path;
417 my $path = @_ ? shift : File::Spec->curdir;
418 CORE::chdir($path) || croak "Cannot chdir to $path: $!";
419 my $realpath = getcwd();
420 -d $cwd && CORE::chdir($cwd) ||
421 croak "Cannot chdir back to $cwd: $!";
425 # added function alias to follow principle of least surprise
426 # based on previous aliasing. --tchrist 27-Jan-00
427 *fast_realpath = \&fast_abs_path;
430 # --- PORTING SECTION ---
432 # VMS: $ENV{'DEFAULT'} points to default directory at all times
433 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
434 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
435 # in the process logical name table as the default device and directory
436 # seen by Perl. This may not be the same as the default device
437 # and directory seen by DCL after Perl exits, since the effects
438 # the CRTL chdir() function persist only until Perl exits.
441 return $ENV{'DEFAULT'};
445 return $ENV{'DEFAULT'} unless @_;
446 my $path = VMS::Filespec::pathify($_[0]);
447 croak("Invalid path name $_[0]") unless defined $path;
448 return VMS::Filespec::rmsexpand($path);
452 $ENV{'PWD'} = `cmd /c cd`;
454 $ENV{'PWD'} =~ s:\\:/:g ;
459 $ENV{'PWD'} = Win32::GetCwd();
460 $ENV{'PWD'} =~ s:\\:/:g ;
464 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
465 defined &Win32::GetCwd);
467 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
470 if (!defined &Dos::GetCwd) {
471 $ENV{'PWD'} = `command /c cd`;
473 $ENV{'PWD'} =~ s:\\:/:g ;
475 $ENV{'PWD'} = Dos::GetCwd();
481 local $ENV{PATH} = '';
482 local $ENV{CDPATH} = '';
483 local $ENV{ENV} = '';
484 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
490 local $ENV{PATH} = '';
491 local $ENV{CDPATH} = '';
492 local $ENV{ENV} = '';
493 my $path = @_ ? shift : '.';
494 my $realpath=`/usr/bin/fullpath -t $path`;
500 $ENV{'PWD'} = EPOC::getcwd();
505 no warnings; # assignments trigger 'subroutine redefined' warning
509 *getcwd = \&_vms_cwd;
510 *fastcwd = \&_vms_cwd;
511 *fastgetcwd = \&_vms_cwd;
512 *abs_path = \&_vms_abs_path;
513 *fast_abs_path = \&_vms_abs_path;
515 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
516 # We assume that &_NT_cwd is defined as an XSUB or in the core.
519 *fastcwd = \&_NT_cwd;
520 *fastgetcwd = \&_NT_cwd;
521 *abs_path = \&fast_abs_path;
522 *realpath = \&fast_abs_path;
524 elsif ($^O eq 'os2') {
525 # sys_cwd may keep the builtin command
526 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
530 *abs_path = \&fast_abs_path;
532 elsif ($^O eq 'dos') {
534 *getcwd = \&_dos_cwd;
535 *fastgetcwd = \&_dos_cwd;
536 *fastcwd = \&_dos_cwd;
537 *abs_path = \&fast_abs_path;
539 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
541 *getcwd = \&_qnx_cwd;
542 *fastgetcwd = \&_qnx_cwd;
543 *fastcwd = \&_qnx_cwd;
544 *abs_path = \&_qnx_abs_path;
545 *fast_abs_path = \&_qnx_abs_path;
547 elsif ($^O eq 'cygwin') {
551 *abs_path = \&fast_abs_path;
553 elsif ($^O eq 'epoc') {
555 *getcwd = \&_epoc_cwd;
556 *fastgetcwd = \&_epoc_cwd;
557 *fastcwd = \&_epoc_cwd;
558 *abs_path = \&fast_abs_path;
560 elsif ($^O eq 'MacOS') {
564 *abs_path = \&fast_abs_path;