.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)

.\"

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.\" Modified Wed Jul 21 22:35:42 1993 by Rik Faith (faith@cs.unc.edu)

.\" Modified 18 Mar 1996 by Martin Schulze (joey@infodrom.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 <rl@hellgate.ch>

.\"

.TH GETCWD 3 2017-09-15 "GNU" "Linux Programmer's Manual"

.SH NAME

getcwd, getwd, get_current_dir_name \- get current working directory

.SH SYNOPSIS

.nf

.B #include <unistd.h>

.PP

.BI "char *getcwd(char *" buf ", size_t " size );

.PP

.BI "char *getwd(char *" buf );

.PP

.B "char *get_current_dir_name(void);"

.fi

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.BR get_current_dir_name ():

.RS

_GNU_SOURCE

.RE

.PP

.BR getwd ():

.ad l

.RS 4

.PD 0

.TP 4

Since glibc 2.12:

.nf

(_XOPEN_SOURCE\ >=\ 500) && ! (_POSIX_C_SOURCE\ >=\ 200809L)

    || /* Glibc since 2.19: */ _DEFAULT_SOURCE

    || /* Glibc versions <= 2.19: */ _BSD_SOURCE

.TP 4

.fi

Before glibc 2.12:

_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500

.\"    || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED

.PD

.RE

.ad b

.SH DESCRIPTION

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

.IR buf ,

if present.

.PP

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

.BR chroot (2)

without changing its current directory into the new root),

then, since Linux 2.6.36,

.\" commit 8df9d1a4142311c084ffeeacb67cd34d190eff74

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.

.PP

The

.BR getcwd ()

function copies an absolute pathname of the current working directory

to the array pointed to by

.IR buf ,

which is of length

.IR size .

.PP

If the length of the absolute pathname of the current working directory,

including the terminating null byte, exceeds

.I size

bytes, NULL is returned, and

.I errno

is set to

.BR ERANGE ;

an application should check for this error, and allocate a larger

buffer if necessary.

.PP

As an extension to the POSIX.1-2001 standard, glibc's

.BR getcwd ()

allocates the buffer dynamically using

.BR malloc (3)

if

.I buf

is NULL.

In this case, the allocated buffer has the length

.I size

unless

.I size

is zero, when

.I buf

is allocated as big as necessary.

The caller should

.BR free (3)

the returned buffer.

.PP

.BR get_current_dir_name ()

will

.BR malloc (3)

an array big enough to hold the absolute pathname of

the current working directory.

If the environment

variable

.B PWD

is set, and its value is correct, then that value will be returned.

The caller should

.BR free (3)

the returned buffer.

.PP

.BR getwd ()

does not

.BR malloc (3)

any memory.

The

.I buf

argument should be a pointer to an array at least

.B PATH_MAX

bytes long.

If the length of the absolute pathname of the current working directory,

including the terminating null byte, exceeds

.B PATH_MAX

bytes, NULL is returned, and

.I errno

is set to

.BR ENAMETOOLONG .

(Note that on some systems,

.B PATH_MAX

may not be a compile-time constant;

furthermore, its value may depend on the filesystem, see

.BR pathconf (3).)

For portability and security reasons, use of

.BR getwd ()

is deprecated.

.SH RETURN VALUE

On success, these functions return a pointer to a string containing

the pathname of the current working directory.

In the case

.BR getcwd ()

and

.BR getwd ()

this is the same value as

.IR buf .

.PP

On failure, these functions return NULL, and

.I errno

is set to indicate the error.

The contents of the array pointed to by

.I buf

are undefined on error.

.SH ERRORS

.TP

.B EACCES

Permission to read or search a component of the filename was denied.

.TP

.B EFAULT

.I buf

points to a bad address.

.TP

.B EINVAL

The

.I size

argument is zero and

.I buf

is not a null pointer.

.TP

.B EINVAL

.BR getwd ():

.I buf

is NULL.

.TP

.B ENAMETOOLONG

.BR getwd ():

The size of the null-terminated absolute pathname string exceeds

.B PATH_MAX

bytes.

.TP

.B ENOENT

The current working directory has been unlinked.

.TP

.B ENOMEM

Out of memory.

.TP

.B ERANGE

The

.I size

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.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lbw22 lb lb

l l l.

Interface	Attribute	Value

T{

.BR getcwd (),

.BR getwd ()

T}	Thread safety	MT-Safe

T{

.BR get_current_dir_name ()

T}	Thread safety	MT-Safe env

.TE

.SH CONFORMING TO

.BR getcwd ()

conforms to POSIX.1-2001.

Note however that POSIX.1-2001 leaves the behavior of

.BR getcwd ()

unspecified if

.I buf

is NULL.

.PP

.BR getwd ()

is present in POSIX.1-2001, but marked LEGACY.

POSIX.1-2008 removes the specification of

.BR getwd ().

Use

.BR getcwd ()

instead.

POSIX.1-2001

does not define any errors for

.BR getwd ().

.PP

.BR get_current_dir_name ()

is a GNU extension.

.SH NOTES

Under Linux, the function

.BR getcwd ()

is a system call (since 2.1.92).

On older systems it would query

.IR /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 with

.BR EACCES .

.PP

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

.BR 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.

.SH SEE ALSO

.BR pwd (1),

.BR chdir (2),

.BR fchdir (2),

.BR open (2),

.BR unlink (2),

.BR free (3),

.BR malloc (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.