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
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.