GeezerVison

NAME

getcwd, getwd — get working directory pathname

SYNOPSIS

#include <unistd.h>

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

char *
getwd(char *buf);

DESCRIPTION

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 not NULL and the length of the pathname plus the terminating NUL character is greater than size, a null pointer is returned and errno is set to ERANGE.

As an extension to IEEE Std 1003.1-2001 (“POSIX.1”), if buf is NULL, space is allocated as necessary to store the pathname. In this case, it is the responsibility of the caller to free(3) the pointer that getcwd() returns.

The deprecated getwd() function is similar to getcwd(), but assumes that buf is non-NULL and has a size of PATH_MAX (as defined by the include file <limits.h>). It does not allocate memory and is provided for source compatibility only. If the length of the pathname plus the terminating NUL character is greater than PATH_MAX, a null pointer is returned. On error, getwd() writes an error message into the memory referenced by buf.

These functions 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 return.

RETURN VALUES

Upon successful completion, a pointer to the pathname is returned. Otherwise a null pointer is returned and errno is set to indicate the error. In addition, getwd() copies the error message associated with errno into the memory referenced by buf.

ERRORS

The getcwd() function will fail if:

[EACCES]

Read or search permission was denied for a component of the pathname.

[EFAULT]

buf points to an invalid address.

[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.

SEE ALSO

pwd(1), chdir(2), malloc(3), strerror(3)

STANDARDS

The getcwd() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”). The ability to specify a null pointer and have getcwd() allocate memory as necessary is an extension.

HISTORY

The getwd() function first appeared in 4.0BSD. The getcwd() function first appeared in AT&T System V Release 1 UNIX and was reimplemented for 4.3BSD-Net/2.

In OpenBSD 4.0, getcwd() was reimplemented on top of the __getcwd() system call. Its calling convention differs from the standard function by requiring buf to not be NULL and by returning an integer, zero on success, and -1 with corresponding errno on failure. This is visible in the output of kdump(1).

BUGS

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