getcwd, get_current_dir_name, getwd - Get current working directory
char *getcwd(char *buf, size_t size);
char *getwd(char *buf);
The getcwd() function copies an absolute pathname of the current working
directory to the array pointed to by buf, which is of length size.
If the current absolute path name would require a buffer longer than
size elements, NULL is returned, and errno is set to ERANGE; an application
should check for this error, and allocate a larger buffer if
If buf is NULL, the behaviour of getcwd() is undefined.
As an extension to the POSIX.1 standard, Linux (libc4, libc5, glibc)
getcwd() allocates the buffer dynamically using malloc() if buf is NULL
on call. In this case, the allocated buffer has the length size unless
size is zero, when buf is allocated as big as necessary. It is possible
(and, indeed, advisable) to free() the buffers if they have been
obtained this way.
get_current_dir_name, which is only prototyped if _GNU_SOURCE is
defined, will malloc(3) an array big enough to hold the current directory
name. If the environment variable PWD is set, and its value is
correct, then that value will be returned.
getwd, which is only prototyped if _BSD_SOURCE or
_XOPEN_SOURCE_EXTENDED is defined, will not malloc(3) any memory. The
buf argument should be a pointer to an array at least PATH_MAX bytes
long. getwd does only return the first PATH_MAX bytes of the actual
NULL on failure (for example, if the current directory is not readable),
with errno set accordingly, and buf on success. The contents of
the array pointed to by buf is undefined on error.
chdir(2), free(3), malloc(3)
GNU 1993-07-21 GETCWD(3)
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