GETCWDGETCWD



GETCWDGETCWD

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
NOTES
SEE ALSO
COLOPHON

NAME

getcwd − get current working directory

SYNOPSIS

/*
* This page documents the getcwd(2) system call, which
* is not defined in any user-space header files; you should
* use getcwd(3) defined in <unistd.h> instead in applications.
*/

long getcwd(char *buf, unsigned long size);

DESCRIPTION

The getcwd() function copies an absolute pathname of the current working directory to the array pointed to by buf, which is of length size.

If the current absolute path name would require a buffer longer than size elements, -1 is returned, and errno is set to ERANGE; an application should check for this error, and allocate a larger buffer if necessary.

If buf is NULL, the behaviour of getcwd() is undefined.

RETURN VALUE

-1 on failure (for example, if the current directory is not readable), with errno set accordingly, and the number of characters stored in buf on success. The contents of the array pointed to by buf is undefined on error.

Note that this return value differs from the getcwd(3) library function, which returns NULL on failure and the address of buf on success.

ERRORS

ENOMEM

if user memory cannot be mapped

ENOENT

if directory does not exist (i.e. it has been deleted)

ERANGE

if not enough space available for storing the path

EFAULT

if memory access violation occurs while copying

CONFORMING TO

The getcwd system call is Linux specific, use the getcwd C library function for portability.

SEE ALSO

getcwd(3)

NAME

getcwd, getwd, get_current_dir_name − Get current working directory

SYNOPSIS

#include <unistd.h>

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

char *getwd(char *buf);

char *get_current_dir_name(void);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

get_current_dir_name():

_GNU_SOURCE

getwd():

Since glibc 2.12:

_BSD_SOURCE ||
(_XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
!(_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)

Before glibc 2.12:

_BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

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 buf, if present.

The getcwd() function copies an absolute pathname of the current working directory to the array pointed to by buf, which is of length size.

If the length of the absolute pathname of the current working directory, including the terminating null byte, exceeds size bytes, NULL is returned, and errno is set to ERANGE; an application should check for this error, and allocate a larger buffer if necessary.

As an extension to the POSIX.1-2001 standard, Linux (libc4, libc5, glibc) getcwd() allocates the buffer dynamically using malloc(3) if buf is NULL. In this case, the allocated buffer has the length size unless size is zero, when buf is allocated as big as necessary. The caller should free(3) the returned buffer.

get_current_dir_name() will 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 buffer.

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 file system, see pathconf(3).) For portability and security reasons, use of getwd() is deprecated.

RETURN VALUE

On success, these functions return a pointer to a string containing the pathname of the current working directory. In the case getcwd() and getwd() this is the same value as buf.

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.

ERRORS

EACCES

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

EFAULT

buf points to a bad address.

EINVAL

The size argument is zero and buf is not a NULL pointer.

EINVAL

getwd(): buf is NULL.

ENAMETOOLONG

getwd(): The size of the null-terminated absolute pathname string exceeds PATH_MAX bytes.

ENOENT

The current working directory has been unlinked.

ERANGE

The 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.

CONFORMING TO

getcwd() conforms to POSIX.1-2001. Note however that POSIX.1-2001 leaves the behavior of getcwd() unspecified if buf is NULL.

getwd() is present in POSIX.1-2001, but marked LEGACY. POSIX.1-2008 removes the specification of getwd(). Use getcwd() instead. POSIX.1-2001 does not define any errors for getwd().

get_current_dir_name() is a GNU extension.

NOTES

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 file system are missing, a generic implementation is called. Only in that case can these calls fail under Linux with EACCES.

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.

SEE ALSO

chdir(2), fchdir(2), open(2), unlink(2), free(3), malloc(3)

COLOPHON

This page is part of release 3.35 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://man7.org/linux/man-pages/.






Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.





Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.


Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.





Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.


Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.





Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.


Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.