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.
77 @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
78 @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
81 # The 'natural and safe form' for UNIX (pwd may be setuid root)
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.
111 # List of metachars taken from do_exec() in doio.c
112 my $quoted_shell_meta = quotemeta('$&*(){}[]";\\|?<>~`'."'\n");
115 my($odev, $oino, $cdev, $cino, $tdev, $tino);
119 my($orig_cdev, $orig_cino) = stat('.');
120 ($cdev, $cino) = ($orig_cdev, $orig_cino);
123 ($odev, $oino) = ($cdev, $cino);
124 CORE::chdir('..') || return undef;
125 ($cdev, $cino) = stat('.');
126 last if $odev == $cdev && $oino == $cino;
127 opendir(DIR, '.') || return undef;
129 $direntry = readdir(DIR);
130 last unless defined $direntry;
131 next if $direntry eq '.';
132 next if $direntry eq '..';
134 ($tdev, $tino) = lstat($direntry);
135 last unless $tdev != $odev || $tino != $oino;
138 return undef unless defined $direntry; # should never happen
139 unshift(@path, $direntry);
141 $path = '/' . join('/', @path);
142 if ($^O eq 'apollo') { $path = "/".$path; }
143 # At this point $path may be tainted (if tainting) and chdir would fail.
144 # To be more useful we untaint it then check that we landed where we started.
145 $path = $1 if $path =~ /^(.*)$/; # untaint
146 CORE::chdir($path) || return undef;
147 ($cdev, $cino) = stat('.');
148 die "Unstable directory path, current directory changed unexpectedly"
149 if $cdev != $orig_cdev || $cino != $orig_cino;
154 # Keeps track of current working directory in PWD environment var
162 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos') {
163 my($dd,$di) = stat('.');
164 my($pd,$pi) = stat($ENV{'PWD'});
165 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
172 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
173 if ($ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|) {
174 my($pd,$pi) = stat($2);
175 my($dd,$di) = stat($1);
176 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
184 my $newdir = shift || ''; # allow for no arg (chdir to HOME dir)
185 $newdir =~ s|///*|/|g;
186 chdir_init() unless $chdir_init;
187 return 0 unless CORE::chdir $newdir;
188 if ($^O eq 'VMS') { return $ENV{'PWD'} = $ENV{'DEFAULT'} }
190 if ($newdir =~ m#^/#) {
191 $ENV{'PWD'} = $newdir;
193 my @curdir = split(m#/#,$ENV{'PWD'});
194 @curdir = ('') unless @curdir;
196 foreach $component (split(m#/#, $newdir)) {
197 next if $component eq '.';
198 pop(@curdir),next if $component eq '..';
199 push(@curdir,$component);
201 $ENV{'PWD'} = join('/',@curdir) || '/';
206 # Taken from Cwd.pm It is really getcwd with an optional
207 # parameter instead of '.'
212 my $start = @_ ? shift : '.';
213 my($dotdots, $cwd, @pst, @cst, $dir, @tst);
215 unless (@cst = stat( $start ))
217 carp "stat($start): $!";
226 unless (opendir(PARENT, $dotdots))
228 carp "opendir($dotdots): $!";
231 unless (@cst = stat($dotdots))
233 carp "stat($dotdots): $!";
237 if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
245 unless (defined ($dir = readdir(PARENT)))
247 carp "readdir($dotdots): $!";
251 $tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
253 while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
256 $cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
258 } while (defined $dir);
259 chop($cwd) unless $cwd eq '/'; # drop the trailing /
263 # added function alias for those of us more
264 # used to the libc function. --tchrist 27-Jan-00
265 *realpath = \&abs_path;
269 my $path = shift || '.';
270 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
271 my $realpath = getcwd();
272 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
276 # added function alias to follow principle of least surprise
277 # based on previous aliasing. --tchrist 27-Jan-00
278 *fast_realpath = \&fast_abs_path;
281 # --- PORTING SECTION ---
283 # VMS: $ENV{'DEFAULT'} points to default directory at all times
284 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
285 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
286 # in the process logical name table as the default device and directory
287 # seen by Perl. This may not be the same as the default device
288 # and directory seen by DCL after Perl exits, since the effects
289 # the CRTL chdir() function persist only until Perl exits.
292 return $ENV{'DEFAULT'};
296 return $ENV{'DEFAULT'} unless @_;
297 my $path = VMS::Filespec::pathify($_[0]);
298 croak("Invalid path name $_[0]") unless defined $path;
299 return VMS::Filespec::rmsexpand($path);
303 $ENV{'PWD'} = `cmd /c cd`;
305 $ENV{'PWD'} =~ s:\\:/:g ;
310 $ENV{'PWD'} = Win32::GetCwd();
311 $ENV{'PWD'} =~ s:\\:/:g ;
315 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
316 defined &Win32::GetCwd);
318 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
321 if (!defined &Dos::GetCwd) {
322 $ENV{'PWD'} = `command /c cd`;
324 $ENV{'PWD'} =~ s:\\:/:g ;
326 $ENV{'PWD'} = Dos::GetCwd();
332 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
338 my $path = shift || '.';
339 my $realpath=`/usr/bin/fullpath -t $path`;
345 local $^W = 0; # assignments trigger 'subroutine redefined' warning
349 *getcwd = \&_vms_cwd;
350 *fastcwd = \&_vms_cwd;
351 *fastgetcwd = \&_vms_cwd;
352 *abs_path = \&_vms_abs_path;
353 *fast_abs_path = \&_vms_abs_path;
355 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
356 # We assume that &_NT_cwd is defined as an XSUB or in the core.
359 *fastcwd = \&_NT_cwd;
360 *fastgetcwd = \&_NT_cwd;
361 *abs_path = \&fast_abs_path;
363 elsif ($^O eq 'os2') {
364 # sys_cwd may keep the builtin command
365 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
369 *abs_path = \&fast_abs_path;
371 elsif ($^O eq 'dos') {
373 *getcwd = \&_dos_cwd;
374 *fastgetcwd = \&_dos_cwd;
375 *fastcwd = \&_dos_cwd;
376 *abs_path = \&fast_abs_path;
378 elsif ($^O eq 'qnx') {
380 *getcwd = \&_qnx_cwd;
381 *fastgetcwd = \&_qnx_cwd;
382 *fastcwd = \&_qnx_cwd;
383 *abs_path = \&_qnx_abs_path;
384 *fast_abs_path = \&_qnx_abs_path;
386 elsif ($^O eq 'cygwin') {
390 *abs_path = \&fast_abs_path;
394 # package main; eval join('',<DATA>) || die $@; # quick test
399 BEGIN { import Cwd qw(:DEFAULT chdir); }
400 print join("\n", cwd, getcwd, fastcwd, "");
402 print join("\n", cwd, getcwd, fastcwd, "");