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 *cwd = \&_backtick_pwd unless defined &cwd;
95 # By Brandon S. Allbery
97 # Usage: $cwd = getcwd();
106 # Usage: $cwd = &fastcwd;
108 # This is a faster version of getcwd. It's also more dangerous because
109 # you might chdir out of a directory that you can't chdir back into.
112 my($odev, $oino, $cdev, $cino, $tdev, $tino);
116 my($orig_cdev, $orig_cino) = stat('.');
117 ($cdev, $cino) = ($orig_cdev, $orig_cino);
120 ($odev, $oino) = ($cdev, $cino);
121 CORE::chdir('..') || return undef;
122 ($cdev, $cino) = stat('.');
123 last if $odev == $cdev && $oino == $cino;
124 opendir(DIR, '.') || return undef;
126 $direntry = readdir(DIR);
127 last unless defined $direntry;
128 next if $direntry eq '.';
129 next if $direntry eq '..';
131 ($tdev, $tino) = lstat($direntry);
132 last unless $tdev != $odev || $tino != $oino;
135 return undef unless defined $direntry; # should never happen
136 unshift(@path, $direntry);
138 $path = '/' . join('/', @path);
139 if ($^O eq 'apollo') { $path = "/".$path; }
140 # At this point $path may be tainted (if tainting) and chdir would fail.
141 # To be more useful we untaint it then check that we landed where we started.
142 $path = $1 if $path =~ /^(.*)\z/s; # untaint
143 CORE::chdir($path) || return undef;
144 ($cdev, $cino) = stat('.');
145 die "Unstable directory path, current directory changed unexpectedly"
146 if $cdev != $orig_cdev || $cino != $orig_cino;
151 # Keeps track of current working directory in PWD environment var
159 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos') {
160 my($dd,$di) = stat('.');
161 my($pd,$pi) = stat($ENV{'PWD'});
162 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
169 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
170 if ($ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
171 my($pd,$pi) = stat($2);
172 my($dd,$di) = stat($1);
173 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
181 my $newdir = shift || ''; # allow for no arg (chdir to HOME dir)
182 $newdir =~ s|///*|/|g;
183 chdir_init() unless $chdir_init;
184 return 0 unless CORE::chdir $newdir;
185 if ($^O eq 'VMS') { return $ENV{'PWD'} = $ENV{'DEFAULT'} }
187 if ($newdir =~ m#^/#s) {
188 $ENV{'PWD'} = $newdir;
190 my @curdir = split(m#/#,$ENV{'PWD'});
191 @curdir = ('') unless @curdir;
193 foreach $component (split(m#/#, $newdir)) {
194 next if $component eq '.';
195 pop(@curdir),next if $component eq '..';
196 push(@curdir,$component);
198 $ENV{'PWD'} = join('/',@curdir) || '/';
203 # Taken from Cwd.pm It is really getcwd with an optional
204 # parameter instead of '.'
209 my $start = @_ ? shift : '.';
210 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
212 unless (@cst = stat( $start ))
214 carp "stat($start): $!";
223 unless (opendir(PARENT, $dotdots))
225 carp "opendir($dotdots): $!";
228 unless (@cst = stat($dotdots))
230 carp "stat($dotdots): $!";
234 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
242 unless (defined ($dir = readdir(PARENT)))
244 carp "readdir($dotdots): $!";
248 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
250 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
253 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
255 } while (defined $dir);
256 chop($cwd) unless $cwd eq '/'; # drop the trailing /
260 # added function alias for those of us more
261 # used to the libc function. --tchrist 27-Jan-00
262 *realpath = \&abs_path;
266 my $path = shift || '.';
267 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
268 my $realpath = getcwd();
269 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
273 # added function alias to follow principle of least surprise
274 # based on previous aliasing. --tchrist 27-Jan-00
275 *fast_realpath = \&fast_abs_path;
278 # --- PORTING SECTION ---
280 # VMS: $ENV{'DEFAULT'} points to default directory at all times
281 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
282 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
283 # in the process logical name table as the default device and directory
284 # seen by Perl. This may not be the same as the default device
285 # and directory seen by DCL after Perl exits, since the effects
286 # the CRTL chdir() function persist only until Perl exits.
289 return $ENV{'DEFAULT'};
293 return $ENV{'DEFAULT'} unless @_;
294 my $path = VMS::Filespec::pathify($_[0]);
295 croak("Invalid path name $_[0]") unless defined $path;
296 return VMS::Filespec::rmsexpand($path);
300 $ENV{'PWD'} = `cmd /c cd`;
302 $ENV{'PWD'} =~ s:\\:/:g ;
307 $ENV{'PWD'} = Win32::GetCwd();
308 $ENV{'PWD'} =~ s:\\:/:g ;
312 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
313 defined &Win32::GetCwd);
315 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
318 if (!defined &Dos::GetCwd) {
319 $ENV{'PWD'} = `command /c cd`;
321 $ENV{'PWD'} =~ s:\\:/:g ;
323 $ENV{'PWD'} = Dos::GetCwd();
329 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
335 my $path = shift || '.';
336 my $realpath=`/usr/bin/fullpath -t $path`;
342 no warnings; # assignments trigger 'subroutine redefined' warning
346 *getcwd = \&_vms_cwd;
347 *fastcwd = \&_vms_cwd;
348 *fastgetcwd = \&_vms_cwd;
349 *abs_path = \&_vms_abs_path;
350 *fast_abs_path = \&_vms_abs_path;
352 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
353 # We assume that &_NT_cwd is defined as an XSUB or in the core.
356 *fastcwd = \&_NT_cwd;
357 *fastgetcwd = \&_NT_cwd;
358 *abs_path = \&fast_abs_path;
360 elsif ($^O eq 'os2') {
361 # sys_cwd may keep the builtin command
362 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
366 *abs_path = \&fast_abs_path;
368 elsif ($^O eq 'dos') {
370 *getcwd = \&_dos_cwd;
371 *fastgetcwd = \&_dos_cwd;
372 *fastcwd = \&_dos_cwd;
373 *abs_path = \&fast_abs_path;
375 elsif ($^O eq 'qnx') {
377 *getcwd = \&_qnx_cwd;
378 *fastgetcwd = \&_qnx_cwd;
379 *fastcwd = \&_qnx_cwd;
380 *abs_path = \&_qnx_abs_path;
381 *fast_abs_path = \&_qnx_abs_path;
383 elsif ($^O eq 'cygwin') {
387 *abs_path = \&fast_abs_path;
391 # package main; eval join('',<DATA>) || die $@; # quick test
396 BEGIN { import Cwd qw(:DEFAULT chdir); }
397 print join("\n", cwd, getcwd, fastcwd, "");
399 print join("\n", cwd, getcwd, fastcwd, "");