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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()  allo-
       cates  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 work-
       ing  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 con-
       tents 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 specifi-
       cation 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 3.53 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)
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