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 On Mac OS (Classic), the path separator is ':', not '/', and the
83 current directory is denoted as ':', not '.'. To move up the directory
84 tree, you will use '::' to move up one level, but ':::' and so on to
85 move up the tree two or more levels (i.e. the equivalent to '../../..'
86 is '::::'). Generally, you should be careful about specifying relative pathnames.
87 While a full path always begins with a volume name, a relative pathname
88 should always begin with a ':'. If specifying a volume name only, a
89 trailing ':' is required.
91 Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
92 functions are all aliases for the C<cwd()> function, which, on Mac OS,
93 calls `pwd`. Likewise, the C<abs_path()> function is an alias for
104 our $VERSION = '2.05';
106 use base qw/ Exporter /;
107 our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
108 our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
110 # sys_cwd may keep the builtin command
112 # All the functionality of this module may provided by builtins,
113 # there is no sense to process the rest of the file.
114 # The best choice may be to have this in BEGIN, but how to return from BEGIN?
116 if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
122 *abs_path = \&sys_abspath;
123 *fast_abs_path = \&abs_path;
124 *realpath = \&abs_path;
125 *fast_realpath = \&abs_path;
131 XSLoader::load('Cwd');
135 # Find the pwd command in the expected locations. We assume these
136 # are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
137 # so everything works under taint mode.
139 foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
147 # The 'natural and safe form' for UNIX (pwd may be setuid root)
149 my $cwd = `$pwd_cmd`;
150 # `pwd` may fail e.g. if the disk is full
151 chomp($cwd) if defined $cwd;
155 # Since some ports may predefine cwd internally (e.g., NT)
156 # we take care not to override an existing definition for cwd().
158 unless(defined &cwd) {
159 # The pwd command is not available in some chroot(2)'ed environments
160 if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
161 *cwd = \&_backtick_pwd;
168 # set a reasonable (and very safe) default for fastgetcwd, in case it
169 # isn't redefined later (20001212 rspier)
172 # By Brandon S. Allbery
174 # Usage: $cwd = getcwd();
181 # Keeps track of current working directory in PWD environment var
189 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
190 my($dd,$di) = stat('.');
191 my($pd,$pi) = stat($ENV{'PWD'});
192 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
198 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
201 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
202 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
203 my($pd,$pi) = stat($2);
204 my($dd,$di) = stat($1);
205 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
213 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
214 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
215 chdir_init() unless $chdir_init;
217 if ($^O eq 'MSWin32') {
218 # get the full path name *before* the chdir()
219 $newpwd = Win32::GetFullPathName($newdir);
222 return 0 unless CORE::chdir $newdir;
225 return $ENV{'PWD'} = $ENV{'DEFAULT'}
227 elsif ($^O eq 'MacOS') {
228 return $ENV{'PWD'} = cwd();
230 elsif ($^O eq 'MSWin32') {
231 $ENV{'PWD'} = $newpwd;
235 if ($newdir =~ m#^/#s) {
236 $ENV{'PWD'} = $newdir;
238 my @curdir = split(m#/#,$ENV{'PWD'});
239 @curdir = ('') unless @curdir;
241 foreach $component (split(m#/#, $newdir)) {
242 next if $component eq '.';
243 pop(@curdir),next if $component eq '..';
244 push(@curdir,$component);
246 $ENV{'PWD'} = join('/',@curdir) || '/';
251 # added function alias for those of us more
252 # used to the libc function. --tchrist 27-Jan-00
253 *realpath = \&abs_path;
258 my $path = @_ ? shift : File::Spec->curdir;
259 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
260 my $realpath = getcwd();
261 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
265 # added function alias to follow principle of least surprise
266 # based on previous aliasing. --tchrist 27-Jan-00
267 *fast_realpath = \&fast_abs_path;
270 # --- PORTING SECTION ---
272 # VMS: $ENV{'DEFAULT'} points to default directory at all times
273 # 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
274 # Note: Use of Cwd::chdir() causes the logical name PWD to be defined
275 # in the process logical name table as the default device and directory
276 # seen by Perl. This may not be the same as the default device
277 # and directory seen by DCL after Perl exits, since the effects
278 # the CRTL chdir() function persist only until Perl exits.
281 return $ENV{'DEFAULT'};
285 return $ENV{'DEFAULT'} unless @_;
286 my $path = VMS::Filespec::pathify($_[0]);
287 croak("Invalid path name $_[0]") unless defined $path;
288 return VMS::Filespec::rmsexpand($path);
292 $ENV{'PWD'} = `cmd /c cd`;
294 $ENV{'PWD'} =~ s:\\:/:g ;
299 $ENV{'PWD'} = Win32::GetCwd();
300 $ENV{'PWD'} =~ s:\\:/:g ;
304 *_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
305 defined &Win32::GetCwd);
307 *_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
310 if (!defined &Dos::GetCwd) {
311 $ENV{'PWD'} = `command /c cd`;
313 $ENV{'PWD'} =~ s:\\:/:g ;
315 $ENV{'PWD'} = Dos::GetCwd();
321 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
327 my $path = @_ ? shift : '.';
328 my $realpath=`/usr/bin/fullpath -t $path`;
334 $ENV{'PWD'} = EPOC::getcwd();
339 no warnings; # assignments trigger 'subroutine redefined' warning
343 *getcwd = \&_vms_cwd;
344 *fastcwd = \&_vms_cwd;
345 *fastgetcwd = \&_vms_cwd;
346 *abs_path = \&_vms_abs_path;
347 *fast_abs_path = \&_vms_abs_path;
349 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
350 # We assume that &_NT_cwd is defined as an XSUB or in the core.
353 *fastcwd = \&_NT_cwd;
354 *fastgetcwd = \&_NT_cwd;
355 *abs_path = \&fast_abs_path;
357 elsif ($^O eq 'os2') {
358 # sys_cwd may keep the builtin command
359 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
363 *abs_path = \&fast_abs_path;
365 elsif ($^O eq 'dos') {
367 *getcwd = \&_dos_cwd;
368 *fastgetcwd = \&_dos_cwd;
369 *fastcwd = \&_dos_cwd;
370 *abs_path = \&fast_abs_path;
372 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
374 *getcwd = \&_qnx_cwd;
375 *fastgetcwd = \&_qnx_cwd;
376 *fastcwd = \&_qnx_cwd;
377 *abs_path = \&_qnx_abs_path;
378 *fast_abs_path = \&_qnx_abs_path;
380 elsif ($^O eq 'cygwin') {
384 *abs_path = \&fast_abs_path;
386 elsif ($^O eq 'epoc') {
388 *getcwd = \&_epoc_cwd;
389 *fastgetcwd = \&_epoc_cwd;
390 *fastcwd = \&_epoc_cwd;
391 *abs_path = \&fast_abs_path;
393 elsif ($^O eq 'MacOS') {
397 *abs_path = \&fast_abs_path;
401 # package main; eval join('',<DATA>) || die $@; # quick test
406 BEGIN { import Cwd qw(:DEFAULT chdir); }
407 print join("\n", cwd, getcwd, fastcwd, "");
409 print join("\n", cwd, getcwd, fastcwd, "");