getwd - get working directory pathname

#include <stdio.h>

char *getcwd(buf, size)
char *buf;
size_t size;

char *getwd(buf)
char *buf;

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 be free’d.

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 directory 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:

Read or search permission was denied for a component of the

The size argument is zero.

A component of the pathname no longer exists.

Insufficient memory is available.

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 getcwd function conforms to ANSI X33.159-1989. The ability to
specify a NULL pointer and have getcwd allocate memory as necessary
is an extension.

The getwd function does not do sufficient error checking and is not
able to return very long, but valid, paths. It is provided for