6 Cwd - get pathname of current working directory
26 use Cwd 'abs_path'; # aka realpath()
27 print abs_path($ENV{'PWD'});
29 use Cwd 'fast_abs_path';
30 print fast_abs_path($ENV{'PWD'});
34 This module provides functions for determining the pathname of the
35 current working directory. By default, it exports the functions
36 cwd(), getcwd(), fastcwd(), and fastgetcwd() into the caller's
37 namespace. Each of these functions are called without arguments and
38 return the absolute path of the current working directory. It is
39 recommended that cwd (or another *cwd() function) be used in I<all>
40 code to ensure portability.
42 The cwd() is the most natural and safe form for the current
43 architecture. For most systems it is identical to `pwd` (but without
44 the trailing line terminator).
46 The getcwd() function re-implements the getcwd(3) (or getwd(3)) functions
49 The fastcwd() function looks the same as getcwd(), but runs faster.
50 It's also more dangerous because it might conceivably chdir() you out
51 of a directory that it can't chdir() you back into. If fastcwd
52 encounters a problem it will return undef but will probably leave you
53 in a different directory. For a measure of extra security, if
54 everything appears to have worked, the fastcwd() function will check
55 that it leaves you in the same directory that it started in. If it has
56 changed it will C<die> with the message "Unstable directory path,
57 current directory changed unexpectedly". That should never happen.
59 The fastgetcwd() function is provided as a synonym for cwd().
61 The abs_path() function takes a single argument and returns the
62 absolute pathname for that argument. It uses the same algorithm as
63 getcwd(). (Actually, getcwd() is abs_path(".")) Symbolic links and
64 relative-path components ("." and "..") are resolved to return the
65 canonical pathname, just like realpath(3). This function is also
66 callable as realpath().
68 The fast_abs_path() function looks the same as abs_path() but runs
69 faster and, like fastcwd(), is more dangerous.
71 If you ask to override your chdir() built-in function, then your PWD
72 environment variable will be kept up to date. (See
73 L<perlsub/Overriding Builtin Functions>.) Note that it will only be
74 kept up to date if all packages which use chdir import it from Cwd.
82 our $VERSION = '2.04';
84 use base qw/ Exporter /;
85 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
86 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
88 # Indicates if the XS portion has been loaded or not
91 # The 'natural and safe form' for UNIX (pwd may be setuid root)
95 # `pwd` may fail e.g. if the disk is full
96 chomp($cwd) if defined $cwd;
100 # Since some ports may predefine cwd internally (e.g., NT)
101 # we take care not to override an existing definition for cwd().
103 unless(defined &cwd) {
104 # The pwd command is not available in some chroot(2)'ed environments
105 if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
106 *cwd = \&_backtick_pwd;
113 # set a reasonable (and very safe) default for fastgetcwd, in case it
114 # isn't redefined later (20001212 rspier)
117 # By Brandon S. Allbery
119 # Usage: $cwd = getcwd();
126 # Now a callout to an XSUB. We have to delay booting of the XSUB
127 # until the first time fastcwd is called since Cwd::cwd is needed in the
128 # building of perl when dynamic loading may be unavailable
132 XSLoader::load("Cwd");
135 return &Cwd::_fastcwd;
139 # Keeps track of current working directory in PWD environment var
147 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
148 my($dd,$di) = stat('.');
149 my($pd,$pi) = stat($ENV{'PWD'});
150 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
156 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
159 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
160 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
161 my($pd,$pi) = stat($2);
162 my($dd,$di) = stat($1);
163 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
171 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
172 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
173 chdir_init() unless $chdir_init;
175 if ($^O eq 'MSWin32') {
176 # get the full path name *before* the chdir()
177 $newpwd = Win32::GetFullPathName($newdir);
180 return 0 unless CORE::chdir $newdir;
183 return $ENV{'PWD'} = $ENV{'DEFAULT'}
185 elsif ($^O eq 'MacOS') {
186 return $ENV{'PWD'} = cwd();
188 elsif ($^O eq 'MSWin32') {
189 $ENV{'PWD'} = $newpwd;
193 if ($newdir =~ m#^/#s) {
194 $ENV{'PWD'} = $newdir;
196 my @curdir = split(m#/#,$ENV{'PWD'});
197 @curdir = ('') unless @curdir;
199 foreach $component (split(m#/#, $newdir)) {
200 next if $component eq '.';
201 pop(@curdir),next if $component eq '..';
202 push(@curdir,$component);
204 $ENV{'PWD'} = join('/',@curdir) || '/';
209 # Now a callout to an XSUB
214 XSLoader::load("Cwd");
217 return &Cwd::_abs_path(@_);
220 # added function alias for those of us more
221 # used to the libc function. --tchrist 27-Jan-00
222 *realpath = \&abs_path;
226 my $path = @_ ? shift : '.';
227 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
228 my $realpath = getcwd();
229 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
233 # added function alias to follow principle of least surprise
234 # based on previous aliasing. --tchrist 27-Jan-00
235 *fast_realpath = \&fast_abs_path;
238 # --- PORTING SECTION ---
240 # VMS: $ENV{'DEFAULT'} points to default directory at all times
241 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
242 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
243 # in the process logical name table as the default device and directory
244 # seen by Perl. This may not be the same as the default device
245 # and directory seen by DCL after Perl exits, since the effects
246 # the CRTL chdir() function persist only until Perl exits.
249 return $ENV{'DEFAULT'};
253 return $ENV{'DEFAULT'} unless @_;
254 my $path = VMS::Filespec::pathify($_[0]);
255 croak("Invalid path name $_[0]") unless defined $path;
256 return VMS::Filespec::rmsexpand($path);
260 $ENV{'PWD'} = `cmd /c cd`;
262 $ENV{'PWD'} =~ s:\\:/:g ;
267 $ENV{'PWD'} = Win32::GetCwd();
268 $ENV{'PWD'} =~ s:\\:/:g ;
272 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
273 defined &Win32::GetCwd);
275 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
278 if (!defined &Dos::GetCwd) {
279 $ENV{'PWD'} = `command /c cd`;
281 $ENV{'PWD'} =~ s:\\:/:g ;
283 $ENV{'PWD'} = Dos::GetCwd();
289 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
295 my $path = @_ ? shift : '.';
296 my $realpath=`/usr/bin/fullpath -t $path`;
302 $ENV{'PWD'} = EPOC::getcwd();
307 no warnings; # assignments trigger 'subroutine redefined' warning
311 *getcwd = \&_vms_cwd;
312 *fastcwd = \&_vms_cwd;
313 *fastgetcwd = \&_vms_cwd;
314 *abs_path = \&_vms_abs_path;
315 *fast_abs_path = \&_vms_abs_path;
317 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
318 # We assume that &_NT_cwd is defined as an XSUB or in the core.
321 *fastcwd = \&_NT_cwd;
322 *fastgetcwd = \&_NT_cwd;
323 *abs_path = \&fast_abs_path;
325 elsif ($^O eq 'os2') {
326 # sys_cwd may keep the builtin command
327 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
331 *abs_path = \&fast_abs_path;
333 elsif ($^O eq 'dos') {
335 *getcwd = \&_dos_cwd;
336 *fastgetcwd = \&_dos_cwd;
337 *fastcwd = \&_dos_cwd;
338 *abs_path = \&fast_abs_path;
340 elsif ($^O eq 'qnx') {
342 *getcwd = \&_qnx_cwd;
343 *fastgetcwd = \&_qnx_cwd;
344 *fastcwd = \&_qnx_cwd;
345 *abs_path = \&_qnx_abs_path;
346 *fast_abs_path = \&_qnx_abs_path;
348 elsif ($^O eq 'cygwin') {
352 *abs_path = \&fast_abs_path;
354 elsif ($^O eq 'epoc') {
356 *getcwd = \&_epoc_cwd;
357 *fastgetcwd = \&_epoc_cwd;
358 *fastcwd = \&_epoc_cwd;
359 *abs_path = \&fast_abs_path;
361 elsif ($^O eq 'MacOS') {
365 *abs_path = \&fast_abs_path;
369 # package main; eval join('',<DATA>) || die $@; # quick test
374 BEGIN { import Cwd qw(:DEFAULT chdir); }
375 print join("\n", cwd, getcwd, fastcwd, "");
377 print join("\n", cwd, getcwd, fastcwd, "");