1 .\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
3 .\" %%%LICENSE_START(VERBATIM)
4 .\" Permission is granted to make and distribute verbatim copies of this
5 .\" manual provided the copyright notice and this permission notice are
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8 .\" Permission is granted to copy and distribute modified versions of this
9 .\" manual under the conditions for verbatim copying, provided that the
10 .\" entire resulting derived work is distributed under the terms of a
11 .\" permission notice identical to this one.
13 .\" Since the Linux kernel and libraries are constantly changing, this
14 .\" manual page may be incorrect or out-of-date. The author(s) assume no
15 .\" responsibility for errors or omissions, or for damages resulting from
16 .\" the use of the information contained herein. The author(s) may not
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18 .\" which is licensed free of charge, as they might when working
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25 .\" Modified Wed Jul 21 22:35:42 1993 by Rik Faith (faith@cs.unc.edu)
26 .\" Modified 18 Mar 1996 by Martin Schulze (joey@infodrom.north.de):
27 .\" Corrected description of getwd().
28 .\" Modified Sat Aug 21 12:32:12 MET 1999 by aeb - applied fix by aj
29 .\" Modified Mon Dec 11 13:32:51 MET 2000 by aeb
30 .\" Modified Thu Apr 22 03:49:15 CEST 2002 by Roger Luethi <rl@hellgate.ch>
32 .TH GETCWD 3 2015-03-02 "GNU" "Linux Programmer's Manual"
34 getcwd, getwd, get_current_dir_name \- get current working directory
37 .B #include <unistd.h>
39 .BI "char *getcwd(char *" buf ", size_t " size );
41 .BI "char *getwd(char *" buf );
43 .B "char *get_current_dir_name(void);"
47 Feature Test Macro Requirements for glibc (see
48 .BR feature_test_macros (7)):
51 .BR get_current_dir_name ():
64 (_XOPEN_SOURCE\ >=\ 500 ||
65 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED) &&
66 !(_POSIX_C_SOURCE\ >=\ 200809L || _XOPEN_SOURCE\ >=\ 700)
70 _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
71 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
76 These functions return a null-terminated string containing an
77 absolute pathname that is the current working directory of
79 The pathname is returned as the function result and via the argument
83 If the current directory is not below the root directory of the current
84 process (e.g. because the process set a new filesystem root
87 without changing its current directory into the new root), the returned
88 path will be prefixed with the string "(unreachable)". Such behavior can
89 also be caused by an unprivileged user by changing the current directory
90 into another mount namespace.
91 When dealing with paths from untrusted sources, callers of these
92 functions should consider checking whether the returned path starts
93 with '/' or '(' to avoid misinterpreting an unreachable path
98 function copies an absolute pathname of the current working directory
99 to the array pointed to by
104 If the length of the absolute pathname of the current working directory,
105 including the terminating null byte, exceeds
107 bytes, NULL is returned, and
111 an application should check for this error, and allocate a larger
114 As an extension to the POSIX.1-2001 standard, glibc's
116 allocates the buffer dynamically using
121 In this case, the allocated buffer has the length
127 is allocated as big as necessary.
132 .BR get_current_dir_name ()
135 an array big enough to hold the absolute pathname of
136 the current working directory.
140 is set, and its value is correct, then that value will be returned.
151 argument should be a pointer to an array at least
154 If the length of the absolute pathname of the current working directory,
155 including the terminating null byte, exceeds
157 bytes, NULL is returned, and
161 (Note that on some systems,
163 may not be a compile-time constant;
164 furthermore, its value may depend on the filesystem, see
166 For portability and security reasons, use of
170 On success, these functions return a pointer to a string containing
171 the pathname of the current working directory.
176 this is the same value as
179 On failure, these functions return NULL, and
181 is set to indicate the error.
182 The contents of the array pointed to by
184 are undefined on error.
188 Permission to read or search a component of the filename was denied.
192 points to a bad address.
199 is not a null pointer.
208 The size of the null-terminated absolute pathname string exceeds
213 The current working directory has been unlinked.
218 argument is less than the length of the absolute pathname of the
219 working directory, including the terminating null byte.
220 You need to allocate a bigger array and try again.
222 For an explanation of the terms used in this section, see
228 Interface Attribute Value
232 T} Thread safety MT-Safe
234 .BR get_current_dir_name ()
235 T} Thread safety MT-Safe env
239 conforms to POSIX.1-2001.
240 Note however that POSIX.1-2001 leaves the behavior of
247 is present in POSIX.1-2001, but marked LEGACY.
248 POSIX.1-2008 removes the specification of
254 does not define any errors for
257 .BR get_current_dir_name ()
260 Under Linux, the function
262 is a system call (since 2.1.92).
263 On older systems it would query
265 If both system call and proc filesystem are missing, a
266 generic implementation is called.
267 Only in that case can
268 these calls fail under Linux with
271 These functions are often used to save the location of the current working
272 directory for the purpose of returning to it later.
274 directory (".") and calling
276 to return is usually a faster and more reliable alternative when sufficiently
277 many file descriptors are available, especially on platforms other than Linux.