1GETCWD(3) Linux Programmer's Manual GETCWD(3)
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6 getcwd, getwd, get_current_dir_name - Get current working directory
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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 getcwd(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
20 get_current_dir_name(): _GNU_SOURCE
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23 These functions return a null-terminated string containing an absolute
24 pathname that is the current working directory of the calling process.
25 The pathname is returned as the function result and via the argument
26 buf, if present.
27 The getcwd() function copies an absolute pathname of the current work‐
29 ing directory to the array pointed to by buf, which is of length size.
30 If the length of the absolute pathname of the current working direc‐
32 tory, including the terminating null byte, exceeds size bytes, NULL is
33 returned, and errno is set to ERANGE; an application should check for
34 this error, and allocate a larger buffer if necessary.
35 As an extension to the POSIX.1-2001 standard, Linux (libc4, libc5,
37 glibc) getcwd() allocates the buffer dynamically using malloc(3) if buf
38 is NULL. In this case, the allocated buffer has the length size unless
39 size is zero, when buf is allocated as big as necessary. The caller
40 should free(3) the returned buffer.
41 get_current_dir_name() will malloc(3) an array big enough to hold the
43 absolute pathname of the current working directory. If the environment
44 variable PWD is set, and its value is correct, then that value will be
45 returned. The caller should free(3) the returned buffer.
46 getwd() does not malloc(3) any memory. The buf argument should be a
48 pointer to an array at least PATH_MAX bytes long. If the length of the
49 absolute pathname of the current working directory, including the ter‐
50 minating null byte, exceeds PATH_MAX bytes, NULL is returned, and errno
51 is set to ENAMETOOLONG. (Note that on some systems, PATH_MAX may not
52 be a compile-time constant; furthermore, its value may depend on the
53 file system, see pathconf(3).) For portability and security reasons,
54 use of getwd() is deprecated.
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57 On success, these functions return a pointer to a string containing the
58 pathname of the current working directory. In the case getcwd() and
59 getwd() this is the same value as buf.
60 On failure, these functions return NULL, and errno is set to indicate
62 the error. The contents of the array pointed to by buf are undefined
63 on error.
64
66 EACCES Permission to read or search a component of the filename was
67 denied.
68 EFAULT buf points to a bad address.
70 EINVAL The size argument is zero and buf is not a null pointer.
72 EINVAL getwd(): buf is NULL.
74 ENAMETOOLONG
76 getwd(): The size of the null-terminated absolute pathname
77 string exceeds PATH_MAX bytes.
78 ENOENT The current working directory has been unlinked.
80 ERANGE The size argument is less than the length of the absolute path‐
82 name of the working directory, including the terminating null
83 byte. You need to allocate a bigger array and try again.
84
86 getcwd() conforms to POSIX.1-2001. Note however that POSIX.1-2001
87 leaves the behavior of getcwd() unspecified if buf is NULL.
88 getwd() is present in POSIX.1-2001, but marked LEGACY. POSIX.1-2008
90 removes the specification of getwd(). Use getcwd() instead.
91 POSIX.1-2001 does not define any errors for getwd().
92 get_current_dir_name() is a GNU extension.
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96 Under Linux, the function getcwd() is a system call (since 2.1.92). On
97 older systems it would query /proc/self/cwd. If both system call and
98 proc file system are missing, a generic implementation is called. Only
99 in that case can these calls fail under Linux with EACCES.
100 These functions are often used to save the location of the current
102 working directory for the purpose of returning to it later. Opening
103 the current directory (".") and calling fchdir(2) to return is usually
104 a faster and more reliable alternative when sufficiently many file
105 descriptors are available, especially on platforms other than Linux.
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108 chdir(2), fchdir(2), open(2), unlink(2), free(3), malloc(3)
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111 This page is part of release 3.25 of the Linux man-pages project. A
112 description of the project, and information about reporting bugs, can
113 be found at http://www.kernel.org/doc/man-pages/.
114GNU 2009-03-31 GETCWD(3)