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
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 =head2 abs_path and friends
75 These functions are exported only on request. They each take a single
76 argument and return the absolute pathname for it. If no argument is
77 given they'll use the current working directory.
83 my $abs_path = abs_path($file);
85 Uses the same algorithm as getcwd(). Symbolic links and relative-path
86 components ("." and "..") are resolved to return the canonical
87 pathname, just like realpath(3).
91 my $abs_path = realpath($file);
93 A synonym for abs_path().
97 my $abs_path = fast_abs_path($file);
99 A more dangerous, but potentially faster version of abs_path.
105 If you ask to override your chdir() built-in function,
109 then your PWD environment variable will be kept up to date. Note that
110 it will only be kept up to date if all packages which use chdir import
120 Since the path seperators are different on some operating systems ('/'
121 on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
122 modules wherever portability is a concern.
126 Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
127 functions are all aliases for the C<cwd()> function, which, on Mac OS,
128 calls `pwd`. Likewise, the C<abs_path()> function is an alias for
143 our $VERSION = '2.08';
145 use base qw/ Exporter /;
146 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
147 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
149 # sys_cwd may keep the builtin command
151 # All the functionality of this module may provided by builtins,
152 # there is no sense to process the rest of the file.
153 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
155 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
161 *abs_path = \&sys_abspath;
162 *fast_abs_path = \&abs_path;
163 *realpath = \&abs_path;
164 *fast_realpath = \&abs_path;
170 no warnings 'redefine';
171 XSLoader::load('Cwd');
175 # Find the pwd command in the expected locations. We assume these
176 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
177 # so everything works under taint mode.
179 foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
186 if (-x '/QOpenSys/bin/pwd') { # OS/400 PASE.
187 $pwd_cmd = '/QOpenSys/bin/pwd' ;
189 # Isn't this wrong? _backtick_pwd() will fail if somenone has
190 # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
191 # See [perl #16774]. --jhi
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 # Untaint it then check that we landed where we started.
274 $path =~ /^(.*)\z/s # untaint
275 && CORE::chdir($1) or return undef;
276 ($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): $!";
373 unless (opendir(PARENT, $dotdots))
375 carp "opendir($dotdots): $!";
378 unless (@cst = stat($dotdots))
380 carp "stat($dotdots): $!";
384 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
392 unless (defined ($dir = readdir(PARENT)))
394 carp "readdir($dotdots): $!";
398 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
400 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
403 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
405 } while (defined $dir);
406 chop($cwd) unless $cwd eq '/'; # drop the trailing /
411 # added function alias for those of us more
412 # used to the libc function. --tchrist 27-Jan-00
413 *realpath = \&abs_path;
419 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
421 # Detaint else we'll explode in taint mode. This is safe because
422 # we're not doing anything dangerous with it.
423 ($path) = $path =~ /(.*)/;
424 ($cwd) = $cwd =~ /(.*)/;
426 CORE::chdir($path) || croak "Cannot chdir to $path: $!";
427 my $realpath = getcwd();
428 -d $cwd && CORE::chdir($cwd) ||
429 croak "Cannot chdir back to $cwd: $!";
433 # added function alias to follow principle of least surprise
434 # based on previous aliasing. --tchrist 27-Jan-00
435 *fast_realpath = \&fast_abs_path;
438 # --- PORTING SECTION ---
440 # VMS: $ENV{'DEFAULT'} points to default directory at all times
441 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
442 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
443 # in the process logical name table as the default device and directory
444 # seen by Perl. This may not be the same as the default device
445 # and directory seen by DCL after Perl exits, since the effects
446 # the CRTL chdir() function persist only until Perl exits.
449 return $ENV{'DEFAULT'};
453 return $ENV{'DEFAULT'} unless @_;
454 my $path = VMS::Filespec::pathify($_[0]);
455 croak("Invalid path name $_[0]") unless defined $path;
456 return VMS::Filespec::rmsexpand($path);
460 $ENV{'PWD'} = `cmd /c cd`;
462 $ENV{'PWD'} =~ s:\\:/:g ;
467 $ENV{'PWD'} = Win32::GetCwd();
468 $ENV{'PWD'} =~ s:\\:/:g ;
472 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
473 defined &Win32::GetCwd);
475 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
478 if (!defined &Dos::GetCwd) {
479 $ENV{'PWD'} = `command /c cd`;
481 $ENV{'PWD'} =~ s:\\:/:g ;
483 $ENV{'PWD'} = Dos::GetCwd();
489 local $ENV{PATH} = '';
490 local $ENV{CDPATH} = '';
491 local $ENV{ENV} = '';
492 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
498 local $ENV{PATH} = '';
499 local $ENV{CDPATH} = '';
500 local $ENV{ENV} = '';
501 my $path = @_ ? shift : '.';
502 my $realpath=`/usr/bin/fullpath -t $path`;
508 $ENV{'PWD'} = EPOC::getcwd();
513 no warnings; # assignments trigger 'subroutine redefined' warning
517 *getcwd = \&_vms_cwd;
518 *fastcwd = \&_vms_cwd;
519 *fastgetcwd = \&_vms_cwd;
520 *abs_path = \&_vms_abs_path;
521 *fast_abs_path = \&_vms_abs_path;
523 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
524 # We assume that &_NT_cwd is defined as an XSUB or in the core.
527 *fastcwd = \&_NT_cwd;
528 *fastgetcwd = \&_NT_cwd;
529 *abs_path = \&fast_abs_path;
530 *realpath = \&fast_abs_path;
532 elsif ($^O eq 'os2') {
533 # sys_cwd may keep the builtin command
534 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
538 *abs_path = \&fast_abs_path;
540 elsif ($^O eq 'dos') {
542 *getcwd = \&_dos_cwd;
543 *fastgetcwd = \&_dos_cwd;
544 *fastcwd = \&_dos_cwd;
545 *abs_path = \&fast_abs_path;
547 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
549 *getcwd = \&_qnx_cwd;
550 *fastgetcwd = \&_qnx_cwd;
551 *fastcwd = \&_qnx_cwd;
552 *abs_path = \&_qnx_abs_path;
553 *fast_abs_path = \&_qnx_abs_path;
555 elsif ($^O eq 'cygwin') {
559 *abs_path = \&fast_abs_path;
561 elsif ($^O eq 'epoc') {
563 *getcwd = \&_epoc_cwd;
564 *fastgetcwd = \&_epoc_cwd;
565 *fastcwd = \&_epoc_cwd;
566 *abs_path = \&fast_abs_path;
568 elsif ($^O eq 'MacOS') {
572 *abs_path = \&fast_abs_path;