getcwd, getwd, get_current_dir_name — get current working directory
These functions return a null-terminated string containing
an absolute pathname that is the current working directory of
the calling process. The pathname is returned as the function
result and via the argument
buf, if present.
If the current directory is not below the root directory of the current process (e.g., because the process set a new filesystem root using chroot(2) without changing its current directory into the new root), then, since Linux 2.6.36, the returned path will be prefixed with the string "(unreachable)". Such behavior can also be caused by an unprivileged user by changing the current directory into another mount namespace. When dealing with paths from untrusted sources, callers of these functions should consider checking whether the returned path starts with '/' or '(' to avoid misinterpreting an unreachable path as a relative path.
getcwd() function copies
an absolute pathname of the current working directory to the
array pointed to by
buf, which is of length
If the length of the absolute pathname of the current
working directory, including the terminating null byte,
NULL is returned, and
set to ERANGE; an application
should check for this error, and allocate a larger buffer if
As an extension to the POSIX.1-2001 standard, glibc's
getcwd() allocates the buffer
dynamically using malloc(3) if
buf is NULL. In this case, the
allocated buffer has the length
size is zero, when
buf is allocated as big as
necessary. The caller should free(3) the returned
malloc(3) an array big
enough to hold the absolute pathname of the current working
directory. If the environment variable
PWD is set, and its value is correct, then
that value will be returned. The caller should free(3) the returned
getwd() does not malloc(3) any memory. The
buf argument should
be a pointer to an array at least
PATH_MAX bytes long. If the length of the
absolute pathname of the current working directory, including
the terminating null byte, exceeds
PATH_MAX bytes, NULL is returned, and
errno is set to ENAMETOOLONG. (Note that on some systems,
PATH_MAX may not be a
compile-time constant; furthermore, its value may depend on
the filesystem, see pathconf(3).) For
portability and security reasons, use of
getwd() is deprecated.
On success, these functions return a pointer to a string
containing the pathname of the current working directory. In
getwd() this is the same value
On failure, these functions return NULL, and
errno is set to indicate the error. The
contents of the array pointed to by
buf are undefined on error.
Permission to read or search a component of the filename was denied.
to a bad address.
argument is zero and
buf is not a null
buf is NULL.
getwd(): The size of
the null-terminated absolute pathname string exceeds
Out of memory.
The current working directory has been unlinked.
argument is less than the length of the absolute
pathname of the working directory, including the
terminating null byte. You need to allocate a bigger
array and try again.
For an explanation of the terms used in this section, see attributes(7).
||Thread safety||MT-Safe env|
getcwd() conforms to
POSIX.1-2001. Note however that POSIX.1-2001 leaves the
getwd() is present in
POSIX.1-2001, but marked LEGACY. POSIX.1-2008 removes the
getcwd() instead. POSIX.1-2001
does not define any errors for
get_current_dir_name() is a
Under Linux, the function
getcwd() is a system call (since 2.1.92).
On older systems it would query
/proc/self/cwd. If both system call and
proc filesystem are missing, a generic implementation is
called. Only in that case can these calls fail under Linux
These functions are often used to save the location of the current working directory for the purpose of returning to it later. Opening the current directory (".") and calling fchdir(2) to return is usually a faster and more reliable alternative when sufficiently many file descriptors are available, especially on platforms other than Linux.
This page is part of release 4.07 of the Linux
man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
Copyright (c) 1993 by Thomas Koenig (ig25rz.uni-karlsruhe.de)
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date. The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein. The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
Modified Wed Jul 21 22:35:42 1993 by Rik Faith (faithcs.unc.edu)
Modified 18 Mar 1996 by Martin Schulze (joeyinfodrom.north.de):
Corrected description of getwd().
Modified Sat Aug 21 12:32:12 MET 1999 by aeb - applied fix by aj
Modified Mon Dec 11 13:32:51 MET 2000 by aeb
Modified Thu Apr 22 03:49:15 CEST 2002 by Roger Luethi <rlhellgate.ch>