GETCWD(3)						     Linux Programmer's Manual							 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 call-
       er 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 environ-
       ment 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 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2010-09-20								 GETCWD(3)