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 $VERSION = '2.04';
84 use base qw/ Exporter /;
85 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
86 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
88 # sys_cwd may keep the builtin command
90 # All the functionality of this module may provided by builtins,
91 # there is no sense to process the rest of the file.
92 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
94 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
100 *abs_path = \&sys_abspath;
101 *fast_abs_path = \&abs_path;
102 *realpath = \&abs_path;
103 *fast_realpath = \&abs_path;
109 XSLoader::load('Cwd');
112 # The 'natural and safe form' for UNIX (pwd may be setuid root)
116 # `pwd` may fail e.g. if the disk is full
117 chomp($cwd) if defined $cwd;
121 # Since some ports may predefine cwd internally (e.g., NT)
122 # we take care not to override an existing definition for cwd().
124 unless(defined &cwd) {
125 # The pwd command is not available in some chroot(2)'ed environments
126 if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
127 *cwd = \&_backtick_pwd;
134 # set a reasonable (and very safe) default for fastgetcwd, in case it
135 # isn't redefined later (20001212 rspier)
138 # By Brandon S. Allbery
140 # Usage: $cwd = getcwd();
147 # Keeps track of current working directory in PWD environment var
155 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
156 my($dd,$di) = stat('.');
157 my($pd,$pi) = stat($ENV{'PWD'});
158 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
164 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
167 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
168 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
169 my($pd,$pi) = stat($2);
170 my($dd,$di) = stat($1);
171 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
179 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
180 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
181 chdir_init() unless $chdir_init;
183 if ($^O eq 'MSWin32') {
184 # get the full path name *before* the chdir()
185 $newpwd = Win32::GetFullPathName($newdir);
188 return 0 unless CORE::chdir $newdir;
191 return $ENV{'PWD'} = $ENV{'DEFAULT'}
193 elsif ($^O eq 'MacOS') {
194 return $ENV{'PWD'} = cwd();
196 elsif ($^O eq 'MSWin32') {
197 $ENV{'PWD'} = $newpwd;
201 if ($newdir =~ m#^/#s) {
202 $ENV{'PWD'} = $newdir;
204 my @curdir = split(m#/#,$ENV{'PWD'});
205 @curdir = ('') unless @curdir;
207 foreach $component (split(m#/#, $newdir)) {
208 next if $component eq '.';
209 pop(@curdir),next if $component eq '..';
210 push(@curdir,$component);
212 $ENV{'PWD'} = join('/',@curdir) || '/';
217 # added function alias for those of us more
218 # used to the libc function. --tchrist 27-Jan-00
219 *realpath = \&abs_path;
223 my $path = @_ ? shift : '.';
224 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
225 my $realpath = getcwd();
226 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
230 # added function alias to follow principle of least surprise
231 # based on previous aliasing. --tchrist 27-Jan-00
232 *fast_realpath = \&fast_abs_path;
235 # --- PORTING SECTION ---
237 # VMS: $ENV{'DEFAULT'} points to default directory at all times
238 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
239 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
240 # in the process logical name table as the default device and directory
241 # seen by Perl. This may not be the same as the default device
242 # and directory seen by DCL after Perl exits, since the effects
243 # the CRTL chdir() function persist only until Perl exits.
246 return $ENV{'DEFAULT'};
250 return $ENV{'DEFAULT'} unless @_;
251 my $path = VMS::Filespec::pathify($_[0]);
252 croak("Invalid path name $_[0]") unless defined $path;
253 return VMS::Filespec::rmsexpand($path);
257 $ENV{'PWD'} = `cmd /c cd`;
259 $ENV{'PWD'} =~ s:\\:/:g ;
264 $ENV{'PWD'} = Win32::GetCwd();
265 $ENV{'PWD'} =~ s:\\:/:g ;
269 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
270 defined &Win32::GetCwd);
272 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
275 if (!defined &Dos::GetCwd) {
276 $ENV{'PWD'} = `command /c cd`;
278 $ENV{'PWD'} =~ s:\\:/:g ;
280 $ENV{'PWD'} = Dos::GetCwd();
286 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
292 my $path = @_ ? shift : '.';
293 my $realpath=`/usr/bin/fullpath -t $path`;
299 $ENV{'PWD'} = EPOC::getcwd();
304 no warnings; # assignments trigger 'subroutine redefined' warning
308 *getcwd = \&_vms_cwd;
309 *fastcwd = \&_vms_cwd;
310 *fastgetcwd = \&_vms_cwd;
311 *abs_path = \&_vms_abs_path;
312 *fast_abs_path = \&_vms_abs_path;
314 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
315 # We assume that &_NT_cwd is defined as an XSUB or in the core.
318 *fastcwd = \&_NT_cwd;
319 *fastgetcwd = \&_NT_cwd;
320 *abs_path = \&fast_abs_path;
322 elsif ($^O eq 'os2') {
323 # sys_cwd may keep the builtin command
324 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
328 *abs_path = \&fast_abs_path;
330 elsif ($^O eq 'dos') {
332 *getcwd = \&_dos_cwd;
333 *fastgetcwd = \&_dos_cwd;
334 *fastcwd = \&_dos_cwd;
335 *abs_path = \&fast_abs_path;
337 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
339 *getcwd = \&_qnx_cwd;
340 *fastgetcwd = \&_qnx_cwd;
341 *fastcwd = \&_qnx_cwd;
342 *abs_path = \&_qnx_abs_path;
343 *fast_abs_path = \&_qnx_abs_path;
345 elsif ($^O eq 'cygwin') {
349 *abs_path = \&fast_abs_path;
351 elsif ($^O eq 'epoc') {
353 *getcwd = \&_epoc_cwd;
354 *fastgetcwd = \&_epoc_cwd;
355 *fastcwd = \&_epoc_cwd;
356 *abs_path = \&fast_abs_path;
358 elsif ($^O eq 'MacOS') {
362 *abs_path = \&fast_abs_path;
366 # package main; eval join('',<DATA>) || die $@; # quick test
371 BEGIN { import Cwd qw(:DEFAULT chdir); }
372 print join("\n", cwd, getcwd, fastcwd, "");
374 print join("\n", cwd, getcwd, fastcwd, "");