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 $VERSION = '2.04';
84 use base qw/ Exporter /;
85 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
86 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
90 XSLoader::load('Cwd');
93 # The 'natural and safe form' for UNIX (pwd may be setuid root)
97 # `pwd` may fail e.g. if the disk is full
98 chomp($cwd) if defined $cwd;
102 # Since some ports may predefine cwd internally (e.g., NT)
103 # we take care not to override an existing definition for cwd().
105 unless(defined &cwd) {
106 # The pwd command is not available in some chroot(2)'ed environments
107 if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
108 *cwd = \&_backtick_pwd;
115 # set a reasonable (and very safe) default for fastgetcwd, in case it
116 # isn't redefined later (20001212 rspier)
119 # By Brandon S. Allbery
121 # Usage: $cwd = getcwd();
128 # Keeps track of current working directory in PWD environment var
136 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
137 my($dd,$di) = stat('.');
138 my($pd,$pi) = stat($ENV{'PWD'});
139 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
145 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
148 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
149 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
150 my($pd,$pi) = stat($2);
151 my($dd,$di) = stat($1);
152 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
160 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
161 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
162 chdir_init() unless $chdir_init;
164 if ($^O eq 'MSWin32') {
165 # get the full path name *before* the chdir()
166 $newpwd = Win32::GetFullPathName($newdir);
169 return 0 unless CORE::chdir $newdir;
172 return $ENV{'PWD'} = $ENV{'DEFAULT'}
174 elsif ($^O eq 'MacOS') {
175 return $ENV{'PWD'} = cwd();
177 elsif ($^O eq 'MSWin32') {
178 $ENV{'PWD'} = $newpwd;
182 if ($newdir =~ m#^/#s) {
183 $ENV{'PWD'} = $newdir;
185 my @curdir = split(m#/#,$ENV{'PWD'});
186 @curdir = ('') unless @curdir;
188 foreach $component (split(m#/#, $newdir)) {
189 next if $component eq '.';
190 pop(@curdir),next if $component eq '..';
191 push(@curdir,$component);
193 $ENV{'PWD'} = join('/',@curdir) || '/';
198 # added function alias for those of us more
199 # used to the libc function. --tchrist 27-Jan-00
200 *realpath = \&abs_path;
204 my $path = @_ ? shift : '.';
205 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
206 my $realpath = getcwd();
207 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
211 # added function alias to follow principle of least surprise
212 # based on previous aliasing. --tchrist 27-Jan-00
213 *fast_realpath = \&fast_abs_path;
216 # --- PORTING SECTION ---
218 # VMS: $ENV{'DEFAULT'} points to default directory at all times
219 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
220 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
221 # in the process logical name table as the default device and directory
222 # seen by Perl. This may not be the same as the default device
223 # and directory seen by DCL after Perl exits, since the effects
224 # the CRTL chdir() function persist only until Perl exits.
227 return $ENV{'DEFAULT'};
231 return $ENV{'DEFAULT'} unless @_;
232 my $path = VMS::Filespec::pathify($_[0]);
233 croak("Invalid path name $_[0]") unless defined $path;
234 return VMS::Filespec::rmsexpand($path);
238 $ENV{'PWD'} = `cmd /c cd`;
240 $ENV{'PWD'} =~ s:\\:/:g ;
245 $ENV{'PWD'} = Win32::GetCwd();
246 $ENV{'PWD'} =~ s:\\:/:g ;
250 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
251 defined &Win32::GetCwd);
253 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
256 if (!defined &Dos::GetCwd) {
257 $ENV{'PWD'} = `command /c cd`;
259 $ENV{'PWD'} =~ s:\\:/:g ;
261 $ENV{'PWD'} = Dos::GetCwd();
267 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
273 my $path = @_ ? shift : '.';
274 my $realpath=`/usr/bin/fullpath -t $path`;
280 $ENV{'PWD'} = EPOC::getcwd();
285 no warnings; # assignments trigger 'subroutine redefined' warning
289 *getcwd = \&_vms_cwd;
290 *fastcwd = \&_vms_cwd;
291 *fastgetcwd = \&_vms_cwd;
292 *abs_path = \&_vms_abs_path;
293 *fast_abs_path = \&_vms_abs_path;
295 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
296 # We assume that &_NT_cwd is defined as an XSUB or in the core.
299 *fastcwd = \&_NT_cwd;
300 *fastgetcwd = \&_NT_cwd;
301 *abs_path = \&fast_abs_path;
303 elsif ($^O eq 'os2') {
304 # sys_cwd may keep the builtin command
305 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
309 *abs_path = \&fast_abs_path;
311 elsif ($^O eq 'dos') {
313 *getcwd = \&_dos_cwd;
314 *fastgetcwd = \&_dos_cwd;
315 *fastcwd = \&_dos_cwd;
316 *abs_path = \&fast_abs_path;
318 elsif ($^O eq 'qnx') {
320 *getcwd = \&_qnx_cwd;
321 *fastgetcwd = \&_qnx_cwd;
322 *fastcwd = \&_qnx_cwd;
323 *abs_path = \&_qnx_abs_path;
324 *fast_abs_path = \&_qnx_abs_path;
326 elsif ($^O eq 'cygwin') {
330 *abs_path = \&fast_abs_path;
332 elsif ($^O eq 'epoc') {
334 *getcwd = \&_epoc_cwd;
335 *fastgetcwd = \&_epoc_cwd;
336 *fastcwd = \&_epoc_cwd;
337 *abs_path = \&fast_abs_path;
339 elsif ($^O eq 'MacOS') {
343 *abs_path = \&fast_abs_path;
347 # package main; eval join('',<DATA>) || die $@; # quick test
352 BEGIN { import Cwd qw(:DEFAULT chdir); }
353 print join("\n", cwd, getcwd, fastcwd, "");
355 print join("\n", cwd, getcwd, fastcwd, "");