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GETCWD(3) BSD Library Functions Manual GETCWD(3)
getcwd, getwd -- get working directory pathname
Standard C Library (libc, -lc)
getcwd(char *buf, size_t size);
The getcwd() function copies the absolute pathname of the current working directory into the
memory referenced by buf and returns a pointer to buf. The size argument is the size, in
bytes, of the array referenced by buf.
If buf is NULL, space is allocated as necessary to store the pathname. This space may later
The function getwd() is a compatibility routine which calls getcwd() with its buf argument
and a size of MAXPATHLEN (as defined in the include file <sys/param.h>). Obviously, buf
should be at least MAXPATHLEN bytes in length.
These routines have traditionally been used by programs to save the name of a working direc-
tory for the purpose of returning to it. A much faster and less error-prone method of
accomplishing this is to open the current directory ('.') and use the fchdir(2) function to
Upon successful completion, a pointer to the pathname is returned. Otherwise a NULL pointer
is returned and the global variable errno is set to indicate the error. In addition,
getwd() copies the error message associated with errno into the memory referenced by buf.
The getcwd() function will fail if:
[EACCES] Read or search permission was denied for a component of the pathname.
[EINVAL] The size argument is zero.
[ENOENT] A component of the pathname no longer exists.
[ENOMEM] Insufficient memory is available.
[ERANGE] The size argument is greater than zero but smaller than the length of the
pathname plus 1.
chdir(2), fchdir(2), malloc(3), strerror(3)
The getwd() and getcwd() functions conform to ISO/IEC 9945-1:1990 (``POSIX.1''). The IEEE
Std 1003.1-2004 (``POSIX.1'') revision marked getwd() as legacy and recommended the use of
getcwd() instead. The IEEE Std 1003.1-2008 (``POSIX.1'') revision removed getwd() from the
The ability to specify a NULL pointer and have getcwd() allocate memory as necessary is an
The getwd() function appeared in 4.0BSD.
As getwd() does not know the length of the supplied buffer, it is possible for a long (but
valid) path to overflow the buffer and provide a means for an attacker to exploit the call-
er. getcwd() should be used in place of getwd() (the latter is only provided for compati-
BSD April 29, 2010 BSD
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