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.
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
49 Unfortunately, cwd() tends to break if called under taint mode.
55 A more dangerous version of getcwd(), but potentially faster.
57 It might conceivably chdir() you out of a directory that it can't
58 chdir() you back into. If fastcwd encounters a problem it will return
59 undef but will probably leave you in a different directory. For a
60 measure of extra security, if everything appears to have worked, the
61 fastcwd() function will check that it leaves you in the same directory
62 that it started in. If it has changed it will C<die> with the message
63 "Unstable directory path, current directory changed
64 unexpectedly". That should never happen.
68 my $cwd = fastgetcwd();
70 The fastgetcwd() function is provided as a synonym for cwd().
75 =head2 abs_path and friends
77 These functions are exported only on request. They each take a single
78 argument and return the absolute pathname for it.
84 my $abs_path = abs_path($file);
86 Uses the same algorithm as getcwd(). Symbolic links and relative-path
87 components ("." and "..") are resolved to return the canonical
88 pathname, just like realpath(3).
92 my $abs_path = realpath($file);
94 A synonym for abs_path().
98 my $abs_path = abs_path($file);
100 A more dangerous, but potentially faster version of abs_path.
106 If you ask to override your chdir() built-in function,
110 then your PWD environment variable will be kept up to date. Note that
111 it will only be kept up to date if all packages which use chdir import
121 Since the path seperators are different on some operating systems ('/'
122 on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
123 modules wherever portability is a concern.
127 Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
128 functions are all aliases for the C<cwd()> function, which, on Mac OS,
129 calls `pwd`. Likewise, the C<abs_path()> function is an alias for
144 our $VERSION = '2.06';
146 use base qw/ Exporter /;
147 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
148 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
150 # sys_cwd may keep the builtin command
152 # All the functionality of this module may provided by builtins,
153 # there is no sense to process the rest of the file.
154 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
156 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
162 *abs_path = \&sys_abspath;
163 *fast_abs_path = \&abs_path;
164 *realpath = \&abs_path;
165 *fast_realpath = \&abs_path;
171 undef *Cwd::fastcwd; # avoid redefinition warning
172 XSLoader::load('Cwd');
176 # Find the pwd command in the expected locations. We assume these
177 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
178 # so everything works under taint mode.
180 foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
188 # The 'natural and safe form' for UNIX (pwd may be setuid root)
190 my $cwd = `$pwd_cmd`;
191 # Belt-and-suspenders in case someone said "undef $/".
193 # `pwd` may fail e.g. if the disk is full
194 chomp($cwd) if defined $cwd;
198 # Since some ports may predefine cwd internally (e.g., NT)
199 # we take care not to override an existing definition for cwd().
201 unless(defined &cwd) {
202 # The pwd command is not available in some chroot(2)'ed environments
203 if( $^O eq 'MacOS' || (defined $ENV{PATH} &&
204 grep { -x "$_/pwd" } split(':', $ENV{PATH})) )
206 *cwd = \&_backtick_pwd;
213 # set a reasonable (and very safe) default for fastgetcwd, in case it
214 # isn't redefined later (20001212 rspier)
217 # By Brandon S. Allbery
219 # Usage: $cwd = getcwd();
229 # Usage: $cwd = &fastcwd;
231 # This is a faster version of getcwd. It's also more dangerous because
232 # you might chdir out of a directory that you can't chdir back into.
235 my($odev, $oino, $cdev, $cino, $tdev, $tino);
239 my($orig_cdev, $orig_cino) = stat('.');
240 ($cdev, $cino) = ($orig_cdev, $orig_cino);
243 ($odev, $oino) = ($cdev, $cino);
244 CORE::chdir('..') || return undef;
245 ($cdev, $cino) = stat('.');
246 last if $odev == $cdev && $oino == $cino;
247 opendir(DIR, '.') || return undef;
249 $direntry = readdir(DIR);
250 last unless defined $direntry;
251 next if $direntry eq '.';
252 next if $direntry eq '..';
254 ($tdev, $tino) = lstat($direntry);
255 last unless $tdev != $odev || $tino != $oino;
258 return undef unless defined $direntry; # should never happen
259 unshift(@path, $direntry);
261 $path = '/' . join('/', @path);
262 if ($^O eq 'apollo') { $path = "/".$path; }
263 # At this point $path may be tainted (if tainting) and chdir would fail.
264 # To be more useful we untaint it then check that we landed where we started.
265 $path = $1 if $path =~ /^(.*)\z/s; # untaint
266 CORE::chdir($path) || return undef;
267 ($cdev, $cino) = stat('.');
268 die "Unstable directory path, current directory changed unexpectedly"
269 if $cdev != $orig_cdev || $cino != $orig_cino;
274 # Keeps track of current working directory in PWD environment var
282 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
283 my($dd,$di) = stat('.');
284 my($pd,$pi) = stat($ENV{'PWD'});
285 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
291 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
294 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
295 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
296 my($pd,$pi) = stat($2);
297 my($dd,$di) = stat($1);
298 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
306 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
307 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
308 chdir_init() unless $chdir_init;
310 if ($^O eq 'MSWin32') {
311 # get the full path name *before* the chdir()
312 $newpwd = Win32::GetFullPathName($newdir);
315 return 0 unless CORE::chdir $newdir;
318 return $ENV{'PWD'} = $ENV{'DEFAULT'}
320 elsif ($^O eq 'MacOS') {
321 return $ENV{'PWD'} = cwd();
323 elsif ($^O eq 'MSWin32') {
324 $ENV{'PWD'} = $newpwd;
328 if ($newdir =~ m#^/#s) {
329 $ENV{'PWD'} = $newdir;
331 my @curdir = split(m#/#,$ENV{'PWD'});
332 @curdir = ('') unless @curdir;
334 foreach $component (split(m#/#, $newdir)) {
335 next if $component eq '.';
336 pop(@curdir),next if $component eq '..';
337 push(@curdir,$component);
339 $ENV{'PWD'} = join('/',@curdir) || '/';
345 # In case the XS version doesn't load.
346 *abs_path = \&_perl_abs_path unless defined &abs_path;
349 my $start = @_ ? shift : '.';
350 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
352 unless (@cst = stat( $start ))
354 carp "stat($start): $!";
363 unless (opendir(PARENT, $dotdots))
365 carp "opendir($dotdots): $!";
368 unless (@cst = stat($dotdots))
370 carp "stat($dotdots): $!";
374 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
382 unless (defined ($dir = readdir(PARENT)))
384 carp "readdir($dotdots): $!";
388 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
390 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
393 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
395 } while (defined $dir);
396 chop($cwd) unless $cwd eq '/'; # drop the trailing /
401 # added function alias for those of us more
402 # used to the libc function. --tchrist 27-Jan-00
403 *realpath = \&abs_path;
408 my $path = @_ ? shift : File::Spec->curdir;
409 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
410 my $realpath = getcwd();
411 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
415 # added function alias to follow principle of least surprise
416 # based on previous aliasing. --tchrist 27-Jan-00
417 *fast_realpath = \&fast_abs_path;
420 # --- PORTING SECTION ---
422 # VMS: $ENV{'DEFAULT'} points to default directory at all times
423 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
424 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
425 # in the process logical name table as the default device and directory
426 # seen by Perl. This may not be the same as the default device
427 # and directory seen by DCL after Perl exits, since the effects
428 # the CRTL chdir() function persist only until Perl exits.
431 return $ENV{'DEFAULT'};
435 return $ENV{'DEFAULT'} unless @_;
436 my $path = VMS::Filespec::pathify($_[0]);
437 croak("Invalid path name $_[0]") unless defined $path;
438 return VMS::Filespec::rmsexpand($path);
442 $ENV{'PWD'} = `cmd /c cd`;
444 $ENV{'PWD'} =~ s:\\:/:g ;
449 $ENV{'PWD'} = Win32::GetCwd();
450 $ENV{'PWD'} =~ s:\\:/:g ;
454 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
455 defined &Win32::GetCwd);
457 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
460 if (!defined &Dos::GetCwd) {
461 $ENV{'PWD'} = `command /c cd`;
463 $ENV{'PWD'} =~ s:\\:/:g ;
465 $ENV{'PWD'} = Dos::GetCwd();
471 local $ENV{PATH} = '';
472 local $ENV{CDPATH} = '';
473 local $ENV{ENV} = '';
474 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
480 local $ENV{PATH} = '';
481 local $ENV{CDPATH} = '';
482 local $ENV{ENV} = '';
483 my $path = @_ ? shift : '.';
484 my $realpath=`/usr/bin/fullpath -t $path`;
490 $ENV{'PWD'} = EPOC::getcwd();
495 no warnings; # assignments trigger 'subroutine redefined' warning
499 *getcwd = \&_vms_cwd;
500 *fastcwd = \&_vms_cwd;
501 *fastgetcwd = \&_vms_cwd;
502 *abs_path = \&_vms_abs_path;
503 *fast_abs_path = \&_vms_abs_path;
505 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
506 # We assume that &_NT_cwd is defined as an XSUB or in the core.
509 *fastcwd = \&_NT_cwd;
510 *fastgetcwd = \&_NT_cwd;
511 *abs_path = \&fast_abs_path;
512 *realpath = \&fast_abs_path;
514 elsif ($^O eq 'os2') {
515 # sys_cwd may keep the builtin command
516 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
520 *abs_path = \&fast_abs_path;
522 elsif ($^O eq 'dos') {
524 *getcwd = \&_dos_cwd;
525 *fastgetcwd = \&_dos_cwd;
526 *fastcwd = \&_dos_cwd;
527 *abs_path = \&fast_abs_path;
529 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
531 *getcwd = \&_qnx_cwd;
532 *fastgetcwd = \&_qnx_cwd;
533 *fastcwd = \&_qnx_cwd;
534 *abs_path = \&_qnx_abs_path;
535 *fast_abs_path = \&_qnx_abs_path;
537 elsif ($^O eq 'cygwin') {
541 *abs_path = \&fast_abs_path;
543 elsif ($^O eq 'epoc') {
545 *getcwd = \&_epoc_cwd;
546 *fastgetcwd = \&_epoc_cwd;
547 *fastcwd = \&_epoc_cwd;
548 *abs_path = \&fast_abs_path;
550 elsif ($^O eq 'MacOS') {
554 *abs_path = \&fast_abs_path;