6 getcwd - get pathname of current working directory
23 use Cwd 'abs_path'; # aka realpath()
24 print abs_path($ENV{'PWD'});
26 use Cwd 'fast_abs_path';
27 print fast_abs_path($ENV{'PWD'});
31 The getcwd() function re-implements the getcwd(3) (or getwd(3)) functions
34 The abs_path() function takes a single argument and returns the
35 absolute pathname for that argument. It uses the same algorithm
36 as getcwd(). (Actually, getcwd() is abs_path(".")) Symbolic links
37 and relative-path components ("." and "..") are resolved to return
38 the canonical pathname, just like realpath(3). Also callable as
41 The fastcwd() function looks the same as getcwd(), but runs faster.
42 It's also more dangerous because it might conceivably chdir() you out
43 of a directory that it can't chdir() you back into. If fastcwd
44 encounters a problem it will return undef but will probably leave you
45 in a different directory. For a measure of extra security, if
46 everything appears to have worked, the fastcwd() function will check
47 that it leaves you in the same directory that it started in. If it has
48 changed it will C<die> with the message "Unstable directory path,
49 current directory changed unexpectedly". That should never happen.
51 The fast_abs_path() function looks the same as abs_path(), but runs faster.
52 And like fastcwd() is more dangerous.
54 The cwd() function looks the same as getcwd and fastgetcwd but is
55 implemented using the most natural and safe form for the current
56 architecture. For most systems it is identical to `pwd` (but without
57 the trailing line terminator).
59 It is recommended that cwd (or another *cwd() function) is used in
60 I<all> code to ensure portability.
62 If you ask to override your chdir() built-in function, then your PWD
63 environment variable will be kept up to date. (See
64 L<perlsub/Overriding Builtin Functions>.) Note that it will only be
65 kept up to date if all packages which use chdir import it from Cwd.
73 our $VERSION = '2.03';
75 use base qw/ Exporter /;
76 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
77 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
80 # The 'natural and safe form' for UNIX (pwd may be setuid root)
84 # `pwd` may fail e.g. if the disk is full
85 chomp($cwd) if defined $cwd;
89 # Since some ports may predefine cwd internally (e.g., NT)
90 # we take care not to override an existing definition for cwd().
92 unless(defined &cwd) {
93 # The pwd command is not available in some chroot(2)'ed environments
94 if(grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
95 *cwd = \&_backtick_pwd;
103 # By Brandon S. Allbery
105 # Usage: $cwd = getcwd();
114 # Usage: $cwd = &fastcwd;
116 # This is a faster version of getcwd. It's also more dangerous because
117 # you might chdir out of a directory that you can't chdir back into.
120 my($odev, $oino, $cdev, $cino, $tdev, $tino);
124 my($orig_cdev, $orig_cino) = stat('.');
125 ($cdev, $cino) = ($orig_cdev, $orig_cino);
128 ($odev, $oino) = ($cdev, $cino);
129 CORE::chdir('..') || return undef;
130 ($cdev, $cino) = stat('.');
131 last if $odev == $cdev && $oino == $cino;
132 opendir(DIR, '.') || return undef;
134 $direntry = readdir(DIR);
135 last unless defined $direntry;
136 next if $direntry eq '.';
137 next if $direntry eq '..';
139 ($tdev, $tino) = lstat($direntry);
140 last unless $tdev != $odev || $tino != $oino;
143 return undef unless defined $direntry; # should never happen
144 unshift(@path, $direntry);
146 $path = '/' . join('/', @path);
147 if ($^O eq 'apollo') { $path = "/".$path; }
148 # At this point $path may be tainted (if tainting) and chdir would fail.
149 # To be more useful we untaint it then check that we landed where we started.
150 $path = $1 if $path =~ /^(.*)\z/s; # untaint
151 CORE::chdir($path) || return undef;
152 ($cdev, $cino) = stat('.');
153 die "Unstable directory path, current directory changed unexpectedly"
154 if $cdev != $orig_cdev || $cino != $orig_cino;
159 # Keeps track of current working directory in PWD environment var
167 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
168 my($dd,$di) = stat('.');
169 my($pd,$pi) = stat($ENV{'PWD'});
170 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
176 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
179 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
180 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
181 my($pd,$pi) = stat($2);
182 my($dd,$di) = stat($1);
183 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
191 my $newdir = @? ? shift : ''; # allow for no arg (chdir to HOME dir)
192 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
193 chdir_init() unless $chdir_init;
194 return 0 unless CORE::chdir $newdir;
196 return $ENV{'PWD'} = $ENV{'DEFAULT'}
198 elsif ($^O eq 'MSWin32') {
199 $ENV{'PWD'} = Win32::GetFullPathName($newdir);
203 if ($newdir =~ m#^/#s) {
204 $ENV{'PWD'} = $newdir;
206 my @curdir = split(m#/#,$ENV{'PWD'});
207 @curdir = ('') unless @curdir;
209 foreach $component (split(m#/#, $newdir)) {
210 next if $component eq '.';
211 pop(@curdir),next if $component eq '..';
212 push(@curdir,$component);
214 $ENV{'PWD'} = join('/',@curdir) || '/';
219 # Taken from Cwd.pm It is really getcwd with an optional
220 # parameter instead of '.'
225 my $start = @_ ? shift : '.';
226 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
228 unless (@cst = stat( $start ))
230 carp "stat($start): $!";
239 unless (opendir(PARENT, $dotdots))
241 carp "opendir($dotdots): $!";
244 unless (@cst = stat($dotdots))
246 carp "stat($dotdots): $!";
250 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
258 unless (defined ($dir = readdir(PARENT)))
260 carp "readdir($dotdots): $!";
264 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
266 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
269 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
271 } while (defined $dir);
272 chop($cwd) unless $cwd eq '/'; # drop the trailing /
276 # added function alias for those of us more
277 # used to the libc function. --tchrist 27-Jan-00
278 *realpath = \&abs_path;
282 my $path = @_ ? shift : '.';
283 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
284 my $realpath = getcwd();
285 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
289 # added function alias to follow principle of least surprise
290 # based on previous aliasing. --tchrist 27-Jan-00
291 *fast_realpath = \&fast_abs_path;
294 # --- PORTING SECTION ---
296 # VMS: $ENV{'DEFAULT'} points to default directory at all times
297 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
298 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
299 # in the process logical name table as the default device and directory
300 # seen by Perl. This may not be the same as the default device
301 # and directory seen by DCL after Perl exits, since the effects
302 # the CRTL chdir() function persist only until Perl exits.
305 return $ENV{'DEFAULT'};
309 return $ENV{'DEFAULT'} unless @_;
310 my $path = VMS::Filespec::pathify($_[0]);
311 croak("Invalid path name $_[0]") unless defined $path;
312 return VMS::Filespec::rmsexpand($path);
316 $ENV{'PWD'} = `cmd /c cd`;
318 $ENV{'PWD'} =~ s:\\:/:g ;
323 $ENV{'PWD'} = Win32::GetCwd();
324 $ENV{'PWD'} =~ s:\\:/:g ;
328 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
329 defined &Win32::GetCwd);
331 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
334 if (!defined &Dos::GetCwd) {
335 $ENV{'PWD'} = `command /c cd`;
337 $ENV{'PWD'} =~ s:\\:/:g ;
339 $ENV{'PWD'} = Dos::GetCwd();
345 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
351 my $path = @_ ? shift : '.';
352 my $realpath=`/usr/bin/fullpath -t $path`;
358 $ENV{'PWD'} = EPOC::getcwd();
363 no warnings; # assignments trigger 'subroutine redefined' warning
367 *getcwd = \&_vms_cwd;
368 *fastcwd = \&_vms_cwd;
369 *fastgetcwd = \&_vms_cwd;
370 *abs_path = \&_vms_abs_path;
371 *fast_abs_path = \&_vms_abs_path;
373 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
374 # We assume that &_NT_cwd is defined as an XSUB or in the core.
377 *fastcwd = \&_NT_cwd;
378 *fastgetcwd = \&_NT_cwd;
379 *abs_path = \&fast_abs_path;
381 elsif ($^O eq 'os2') {
382 # sys_cwd may keep the builtin command
383 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
387 *abs_path = \&fast_abs_path;
389 elsif ($^O eq 'dos') {
391 *getcwd = \&_dos_cwd;
392 *fastgetcwd = \&_dos_cwd;
393 *fastcwd = \&_dos_cwd;
394 *abs_path = \&fast_abs_path;
396 elsif ($^O eq 'qnx') {
398 *getcwd = \&_qnx_cwd;
399 *fastgetcwd = \&_qnx_cwd;
400 *fastcwd = \&_qnx_cwd;
401 *abs_path = \&_qnx_abs_path;
402 *fast_abs_path = \&_qnx_abs_path;
404 elsif ($^O eq 'cygwin') {
408 *abs_path = \&fast_abs_path;
410 elsif ($^O eq 'epoc') {
411 *getcwd = \&_epoc_cwd;
412 *fastgetcwd = \&_epoc_cwd;
413 *fastcwd = \&_epoc_cwd;
414 *abs_path = \&fast_abs_path;
418 # package main; eval join('',<DATA>) || die $@; # quick test
423 BEGIN { import Cwd qw(:DEFAULT chdir); }
424 print join("\n", cwd, getcwd, fastcwd, "");
426 print join("\n", cwd, getcwd, fastcwd, "");