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
141 our $VERSION = '2.08';
143 use base qw/ Exporter /;
144 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
145 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
147 # sys_cwd may keep the builtin command
149 # All the functionality of this module may provided by builtins,
150 # there is no sense to process the rest of the file.
151 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
153 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
159 *abs_path = \&sys_abspath;
160 *fast_abs_path = \&abs_path;
161 *realpath = \&abs_path;
162 *fast_realpath = \&abs_path;
169 XSLoader::load('Cwd');
173 # Find the pwd command in the expected locations. We assume these
174 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
175 # so everything works under taint mode.
177 foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
184 if (-x '/QOpenSys/bin/pwd') { # OS/400 PASE.
185 $pwd_cmd = '/QOpenSys/bin/pwd' ;
187 # Isn't this wrong? _backtick_pwd() will fail if somenone has
188 # pwd in their path but it is not /bin/pwd or /usr/bin/pwd?
189 # See [perl #16774]. --jhi
194 # The 'natural and safe form' for UNIX (pwd may be setuid root)
196 local @ENV{qw(PATH IFS CDPATH ENV BASH_ENV)};
197 my $cwd = `$pwd_cmd`;
198 # Belt-and-suspenders in case someone said "undef $/".
200 # `pwd` may fail e.g. if the disk is full
201 chomp($cwd) if defined $cwd;
205 # Since some ports may predefine cwd internally (e.g., NT)
206 # we take care not to override an existing definition for cwd().
208 unless(defined &cwd) {
209 # The pwd command is not available in some chroot(2)'ed environments
210 if( $^O eq 'MacOS' || (defined $ENV{PATH} &&
211 grep { -x "$_/pwd" } split(':', $ENV{PATH})) )
213 *cwd = \&_backtick_pwd;
220 # set a reasonable (and very safe) default for fastgetcwd, in case it
221 # isn't redefined later (20001212 rspier)
224 # By Brandon S. Allbery
226 # Usage: $cwd = getcwd();
236 # Usage: $cwd = &fastcwd;
238 # This is a faster version of getcwd. It's also more dangerous because
239 # you might chdir out of a directory that you can't chdir back into.
242 my($odev, $oino, $cdev, $cino, $tdev, $tino);
246 my($orig_cdev, $orig_cino) = stat('.');
247 ($cdev, $cino) = ($orig_cdev, $orig_cino);
250 ($odev, $oino) = ($cdev, $cino);
251 CORE::chdir('..') || return undef;
252 ($cdev, $cino) = stat('.');
253 last if $odev == $cdev && $oino == $cino;
254 opendir(DIR, '.') || return undef;
256 $direntry = readdir(DIR);
257 last unless defined $direntry;
258 next if $direntry eq '.';
259 next if $direntry eq '..';
261 ($tdev, $tino) = lstat($direntry);
262 last unless $tdev != $odev || $tino != $oino;
265 return undef unless defined $direntry; # should never happen
266 unshift(@path, $direntry);
268 $path = '/' . join('/', @path);
269 if ($^O eq 'apollo') { $path = "/".$path; }
270 # At this point $path may be tainted (if tainting) and chdir would fail.
271 # Untaint it then check that we landed where we started.
272 $path =~ /^(.*)\z/s # untaint
273 && CORE::chdir($1) or return undef;
274 ($cdev, $cino) = stat('.');
275 die "Unstable directory path, current directory changed unexpectedly"
276 if $cdev != $orig_cdev || $cino != $orig_cino;
281 # Keeps track of current working directory in PWD environment var
289 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
290 my($dd,$di) = stat('.');
291 my($pd,$pi) = stat($ENV{'PWD'});
292 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
298 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
301 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
302 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
303 my($pd,$pi) = stat($2);
304 my($dd,$di) = stat($1);
305 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
313 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
314 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
315 chdir_init() unless $chdir_init;
317 if ($^O eq 'MSWin32') {
318 # get the full path name *before* the chdir()
319 $newpwd = Win32::GetFullPathName($newdir);
322 return 0 unless CORE::chdir $newdir;
325 return $ENV{'PWD'} = $ENV{'DEFAULT'}
327 elsif ($^O eq 'MacOS') {
328 return $ENV{'PWD'} = cwd();
330 elsif ($^O eq 'MSWin32') {
331 $ENV{'PWD'} = $newpwd;
335 if ($newdir =~ m#^/#s) {
336 $ENV{'PWD'} = $newdir;
338 my @curdir = split(m#/#,$ENV{'PWD'});
339 @curdir = ('') unless @curdir;
341 foreach $component (split(m#/#, $newdir)) {
342 next if $component eq '.';
343 pop(@curdir),next if $component eq '..';
344 push(@curdir,$component);
346 $ENV{'PWD'} = join('/',@curdir) || '/';
352 # In case the XS version doesn't load.
353 *abs_path = \&_perl_abs_path unless defined &abs_path;
356 my $start = @_ ? shift : '.';
357 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
359 unless (@cst = stat( $start ))
362 Carp::carp ("stat($start): $!");
372 unless (opendir(PARENT, $dotdots))
375 Carp::carp ("opendir($dotdots): $!");
378 unless (@cst = stat($dotdots))
381 Carp::carp ("stat($dotdots): $!");
385 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
393 unless (defined ($dir = readdir(PARENT)))
396 Carp::carp ("readdir($dotdots): $!");
400 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
402 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
405 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
407 } while (defined $dir);
408 chop($cwd) unless $cwd eq '/'; # drop the trailing /
413 # added function alias for those of us more
414 # used to the libc function. --tchrist 27-Jan-00
415 *realpath = \&abs_path;
421 my $path = @_ ? shift : ($Curdir ||= File::Spec->curdir);
423 # Detaint else we'll explode in taint mode. This is safe because
424 # we're not doing anything dangerous with it.
425 ($path) = $path =~ /(.*)/;
426 ($cwd) = $cwd =~ /(.*)/;
428 if (!CORE::chdir($path)) {
430 Carp::croak ("Cannot chdir to $path: $!");
432 my $realpath = getcwd();
433 if (! ((-d $cwd) && (CORE::chdir($cwd)))) {
435 Carp::croak ("Cannot chdir back to $cwd: $!");
440 # added function alias to follow principle of least surprise
441 # based on previous aliasing. --tchrist 27-Jan-00
442 *fast_realpath = \&fast_abs_path;
445 # --- PORTING SECTION ---
447 # VMS: $ENV{'DEFAULT'} points to default directory at all times
448 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
449 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
450 # in the process logical name table as the default device and directory
451 # seen by Perl. This may not be the same as the default device
452 # and directory seen by DCL after Perl exits, since the effects
453 # the CRTL chdir() function persist only until Perl exits.
456 return $ENV{'DEFAULT'};
460 return $ENV{'DEFAULT'} unless @_;
461 my $path = VMS::Filespec::pathify($_[0]);
465 Carp::croak("Invalid path name $_[0]")
467 return VMS::Filespec::rmsexpand($path);
471 $ENV{'PWD'} = `cmd /c cd`;
473 $ENV{'PWD'} =~ s:\\:/:g ;
478 $ENV{'PWD'} = Win32::GetCwd();
479 $ENV{'PWD'} =~ s:\\:/:g ;
483 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
484 defined &Win32::GetCwd);
486 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
489 if (!defined &Dos::GetCwd) {
490 $ENV{'PWD'} = `command /c cd`;
492 $ENV{'PWD'} =~ s:\\:/:g ;
494 $ENV{'PWD'} = Dos::GetCwd();
500 local $ENV{PATH} = '';
501 local $ENV{CDPATH} = '';
502 local $ENV{ENV} = '';
503 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
509 local $ENV{PATH} = '';
510 local $ENV{CDPATH} = '';
511 local $ENV{ENV} = '';
512 my $path = @_ ? shift : '.';
515 open(REALPATH, '-|', '/usr/bin/fullpath', '-t', $path) or
516 die "Can't open /usr/bin/fullpath: $!";
517 my $realpath = <REALPATH>;
524 $ENV{'PWD'} = EPOC::getcwd();
529 no warnings; # assignments trigger 'subroutine redefined' warning
533 *getcwd = \&_vms_cwd;
534 *fastcwd = \&_vms_cwd;
535 *fastgetcwd = \&_vms_cwd;
536 *abs_path = \&_vms_abs_path;
537 *fast_abs_path = \&_vms_abs_path;
539 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
540 # We assume that &_NT_cwd is defined as an XSUB or in the core.
543 *fastcwd = \&_NT_cwd;
544 *fastgetcwd = \&_NT_cwd;
545 *abs_path = \&fast_abs_path;
546 *realpath = \&fast_abs_path;
548 elsif ($^O eq 'os2') {
549 # sys_cwd may keep the builtin command
550 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
554 *abs_path = \&fast_abs_path;
556 elsif ($^O eq 'dos') {
558 *getcwd = \&_dos_cwd;
559 *fastgetcwd = \&_dos_cwd;
560 *fastcwd = \&_dos_cwd;
561 *abs_path = \&fast_abs_path;
563 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
565 *getcwd = \&_qnx_cwd;
566 *fastgetcwd = \&_qnx_cwd;
567 *fastcwd = \&_qnx_cwd;
568 *abs_path = \&_qnx_abs_path;
569 *fast_abs_path = \&_qnx_abs_path;
571 elsif ($^O eq 'cygwin') {
575 *abs_path = \&fast_abs_path;
577 elsif ($^O eq 'epoc') {
579 *getcwd = \&_epoc_cwd;
580 *fastgetcwd = \&_epoc_cwd;
581 *fastcwd = \&_epoc_cwd;
582 *abs_path = \&fast_abs_path;
584 elsif ($^O eq 'MacOS') {
588 *abs_path = \&fast_abs_path;