6 getcwd - get pathname of current working directory
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 algoritm as
36 getcwd(). (actually getcwd() is abs_path("."))
38 The fastcwd() function looks the same as getcwd(), but runs faster.
39 It's also more dangerous because it might conceivably chdir() you out
40 of a directory that it can't chdir() you back into. If fastcwd
41 encounters a problem it will return undef but will probably leave you
42 in a different directory. For a measure of extra security, if
43 everything appears to have worked, the fastcwd() function will check
44 that it leaves you in the same directory that it started in. If it has
45 changed it will C<die> with the message "Unstable directory path,
46 current directory changed unexpectedly". That should never happen.
48 The fast_abs_path() function looks the same as abs_path(), but runs faster.
49 And like fastcwd() is more dangerous.
51 The cwd() function looks the same as getcwd and fastgetcwd but is
52 implemented using the most natural and safe form for the current
53 architecture. For most systems it is identical to `pwd` (but without
54 the trailing line terminator).
56 It is recommended that cwd (or another *cwd() function) is used in
57 I<all> code to ensure portability.
59 If you ask to override your chdir() built-in function, then your PWD
60 environment variable will be kept up to date. (See
61 L<perlsub/Overriding Builtin Functions>.) Note that it will only be
62 kept up to date if all packages which use chdir import it from Cwd.
74 @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
75 @EXPORT_OK = qw(chdir abs_path fast_abs_path);
78 # The 'natural and safe form' for UNIX (pwd may be setuid root)
86 # Since some ports may predefine cwd internally (e.g., NT)
87 # we take care not to override an existing definition for cwd().
89 *cwd = \&_backtick_pwd unless defined &cwd;
92 # By Brandon S. Allbery
94 # Usage: $cwd = getcwd();
103 # Usage: $cwd = &fastcwd;
105 # This is a faster version of getcwd. It's also more dangerous because
106 # you might chdir out of a directory that you can't chdir back into.
108 # List of metachars taken from do_exec() in doio.c
109 my $quoted_shell_meta = quotemeta('$&*(){}[]";\\|?<>~`'."'\n");
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, $cino);
121 chdir('..') || return undef;
122 ($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 # At this point $path may be tainted (if tainting) and chdir would fail.
140 # To be more useful we untaint it then check that we landed where we started.
141 $path = $1 if $path =~ /^(.*)$/; # untaint
142 chdir($path) || return undef;
143 ($cdev, $cino) = stat('.');
144 die "Unstable directory path, current directory changed unexpectedly"
145 if $cdev != $orig_cdev || $cino != $orig_cino;
150 # Keeps track of current working directory in PWD environment var
158 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos') {
159 my($dd,$di) = stat('.');
160 my($pd,$pi) = stat($ENV{'PWD'});
161 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
168 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
169 if ($ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|) {
170 my($pd,$pi) = stat($2);
171 my($dd,$di) = stat($1);
172 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
180 my $newdir = shift || ''; # allow for no arg (chdir to HOME dir)
181 $newdir =~ s|///*|/|g;
182 chdir_init() unless $chdir_init;
183 return 0 unless CORE::chdir $newdir;
184 if ($^O eq 'VMS') { return $ENV{'PWD'} = $ENV{'DEFAULT'} }
186 if ($newdir =~ m#^/#) {
187 $ENV{'PWD'} = $newdir;
189 my @curdir = split(m#/#,$ENV{'PWD'});
190 @curdir = ('') unless @curdir;
192 foreach $component (split(m#/#, $newdir)) {
193 next if $component eq '.';
194 pop(@curdir),next if $component eq '..';
195 push(@curdir,$component);
197 $ENV{'PWD'} = join('/',@curdir) || '/';
202 # Taken from Cwd.pm It is really getcwd with an optional
203 # parameter instead of '.'
208 my $start = @_ ? shift : '.';
209 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
211 unless (@cst = stat( $start ))
213 carp "stat($start): $!";
222 unless (opendir(PARENT, $dotdots))
224 carp "opendir($dotdots): $!";
227 unless (@cst = stat($dotdots))
229 carp "stat($dotdots): $!";
233 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
241 unless (defined ($dir = readdir(PARENT)))
243 carp "readdir($dotdots): $!";
247 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
249 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
252 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
254 } while (defined $dir);
255 chop($cwd) unless $cwd eq '/'; # drop the trailing /
261 my $path = shift || '.';
262 chdir($path) || croak "Cannot chdir to $path:$!";
263 my $realpath = getcwd();
264 chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
269 # --- PORTING SECTION ---
271 # VMS: $ENV{'DEFAULT'} points to default directory at all times
272 # 06-Mar-1996 Charles Bailey bailey@genetics.upenn.edu
273 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
274 # in the process logical name table as the default device and directory
275 # seen by Perl. This may not be the same as the default device
276 # and directory seen by DCL after Perl exits, since the effects
277 # the CRTL chdir() function persist only until Perl exits.
280 return $ENV{'DEFAULT'};
284 return $ENV{'DEFAULT'} unless @_;
285 my $path = VMS::Filespec::pathify($_[0]);
286 croak("Invalid path name $_[0]") unless defined $path;
287 return VMS::Filespec::rmsexpand($path);
291 $ENV{'PWD'} = `cmd /c cd`;
293 $ENV{'PWD'} =~ s:\\:/:g ;
298 $ENV{'PWD'} = Win32::GetCwd();
299 $ENV{'PWD'} =~ s:\\:/:g ;
303 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
304 defined &Win32::GetCwd);
306 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
309 if (!defined &Dos::GetCwd) {
310 $ENV{'PWD'} = `command /c cd`;
312 $ENV{'PWD'} =~ s:\\:/:g ;
314 $ENV{'PWD'} = Dos::GetCwd();
320 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
326 my $path = shift || '.';
327 my $realpath=`/usr/bin/fullpath -t $path`;
333 local $^W = 0; # assignments trigger 'subroutine redefined' warning
337 *getcwd = \&_vms_cwd;
338 *fastcwd = \&_vms_cwd;
339 *fastgetcwd = \&_vms_cwd;
340 *abs_path = \&_vms_abs_path;
341 *fast_abs_path = \&_vms_abs_path;
343 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
344 # We assume that &_NT_cwd is defined as an XSUB or in the core.
347 *fastcwd = \&_NT_cwd;
348 *fastgetcwd = \&_NT_cwd;
349 *abs_path = \&fast_abs_path;
351 elsif ($^O eq 'os2') {
352 # sys_cwd may keep the builtin command
353 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
357 *abs_path = \&fast_abs_path;
359 elsif ($^O eq 'dos') {
361 *getcwd = \&_dos_cwd;
362 *fastgetcwd = \&_dos_cwd;
363 *fastcwd = \&_dos_cwd;
364 *abs_path = \&fast_abs_path;
366 elsif ($^O eq 'qnx') {
368 *getcwd = \&_qnx_cwd;
369 *fastgetcwd = \&_qnx_cwd;
370 *fastcwd = \&_qnx_cwd;
371 *abs_path = \&_qnx_abs_path;
372 *fast_abs_path = \&_qnx_abs_path;
376 # package main; eval join('',<DATA>) || die $@; # quick test
381 BEGIN { import Cwd qw(:DEFAULT chdir); }
382 print join("\n", cwd, getcwd, fastcwd, "");
384 print join("\n", cwd, getcwd, fastcwd, "");