1GETCWD(3) Linux Programmer's Manual GETCWD(3)
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6 getcwd, getwd, get_current_dir_name - get current working directory
7
9 #include <unistd.h>
10 char *getcwd(char *buf, size_t size);
12 char *getwd(char *buf);
14 char *get_current_dir_name(void);
16 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
18 get_current_dir_name():
20 _GNU_SOURCE
21 getwd():
23 Since glibc 2.12:
24 _BSD_SOURCE ||
25 (_XOPEN_SOURCE >= 500 ||
26 _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
27 !(_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)
28 Before glibc 2.12:
29 _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
30 _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
31
33 These functions return a null-terminated string containing an absolute
34 pathname that is the current working directory of the calling process.
35 The pathname is returned as the function result and via the argument
36 buf, if present.
37 The getcwd() function copies an absolute pathname of the current work‐
39 ing directory to the array pointed to by buf, which is of length size.
40 If the length of the absolute pathname of the current working direc‐
42 tory, including the terminating null byte, exceeds size bytes, NULL is
43 returned, and errno is set to ERANGE; an application should check for
44 this error, and allocate a larger buffer if necessary.
45 As an extension to the POSIX.1-2001 standard, Linux (libc4, libc5,
47 glibc) getcwd() allocates the buffer dynamically using malloc(3) if buf
48 is NULL. In this case, the allocated buffer has the length size unless
49 size is zero, when buf is allocated as big as necessary. The caller
50 should free(3) the returned buffer.
51 get_current_dir_name() will malloc(3) an array big enough to hold the
53 absolute pathname of the current working directory. If the environment
54 variable PWD is set, and its value is correct, then that value will be
55 returned. The caller should free(3) the returned buffer.
56 getwd() does not malloc(3) any memory. The buf argument should be a
58 pointer to an array at least PATH_MAX bytes long. If the length of the
59 absolute pathname of the current working directory, including the ter‐
60 minating null byte, exceeds PATH_MAX bytes, NULL is returned, and errno
61 is set to ENAMETOOLONG. (Note that on some systems, PATH_MAX may not
62 be a compile-time constant; furthermore, its value may depend on the
63 file system, see pathconf(3).) For portability and security reasons,
64 use of getwd() is deprecated.
65
67 On success, these functions return a pointer to a string containing the
68 pathname of the current working directory. In the case getcwd() and
69 getwd() this is the same value as buf.
70 On failure, these functions return NULL, and errno is set to indicate
72 the error. The contents of the array pointed to by buf are undefined
73 on error.
74
76 EACCES Permission to read or search a component of the filename was
77 denied.
78 EFAULT buf points to a bad address.
80 EINVAL The size argument is zero and buf is not a NULL pointer.
82 EINVAL getwd(): buf is NULL.
84 ENAMETOOLONG
86 getwd(): The size of the null-terminated absolute pathname
87 string exceeds PATH_MAX bytes.
88 ENOENT The current working directory has been unlinked.
90 ERANGE The size argument is less than the length of the absolute path‐
92 name of the working directory, including the terminating null
93 byte. You need to allocate a bigger array and try again.
94
96 getcwd() conforms to POSIX.1-2001. Note however that POSIX.1-2001
97 leaves the behavior of getcwd() unspecified if buf is NULL.
98 getwd() is present in POSIX.1-2001, but marked LEGACY. POSIX.1-2008
100 removes the specification of getwd(). Use getcwd() instead.
101 POSIX.1-2001 does not define any errors for getwd().
102 get_current_dir_name() is a GNU extension.
104
106 Under Linux, the function getcwd() is a system call (since 2.1.92). On
107 older systems it would query /proc/self/cwd. If both system call and
108 proc file system are missing, a generic implementation is called. Only
109 in that case can these calls fail under Linux with EACCES.
110 These functions are often used to save the location of the current
112 working directory for the purpose of returning to it later. Opening
113 the current directory (".") and calling fchdir(2) to return is usually
114 a faster and more reliable alternative when sufficiently many file
115 descriptors are available, especially on platforms other than Linux.
116
118 chdir(2), fchdir(2), open(2), unlink(2), free(3), malloc(3)
119
121 This page is part of release 3.53 of the Linux man-pages project. A
122 description of the project, and information about reporting bugs, can
123 be found at http://www.kernel.org/doc/man-pages/.
124GNU 2010-09-20 GETCWD(3)