GETCWD(3)						     Linux Programmer's Manual							 GETCWD(3)

NAME

       getcwd, get_current_dir_name, getwd - Get current working directory

SYNOPSIS

       #include <unistd.h>

       char *getcwd(char *buf, size_t size);
       char *get_current_dir_name(void);
       char *getwd(char *buf);

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, NULL is returned, and errno is set to ERANGE; an appli-
       cation should check for this error, and allocate a larger buffer if necessary.

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

       As an extension to the POSIX.1 standard, Linux (libc4, libc5, glibc) getcwd() allocates the buffer dynamically using  malloc()  if  buf	is
       NULL  on  call.	In this case, the allocated buffer has the length size unless size is zero, when buf is allocated as big as necessary.	It
       is possible (and, indeed, advisable) to free() the buffers if they have been obtained this way.

       get_current_dir_name, which is only prototyped if _GNU_SOURCE is defined, will malloc(3) an array big enough to hold the current  directory
       name.  If the environment variable PWD is set, and its value is correct, then that value will be returned.

       getwd, which is only prototyped if _BSD_SOURCE or _XOPEN_SOURCE_EXTENDED is defined, will not malloc(3) any memory. The buf argument should
       be a pointer to an array at least PATH_MAX bytes long.  getwd does only return the first PATH_MAX bytes of the actual pathname.	Note  that
       PATH_MAX  need not be a compile-time constant; it may depend on the filesystem and may even be unlimited. For portability and security rea-
       sons, use of getwd is deprecated.

RETURN VALUE

       NULL on failure with errno set accordingly, and buf on success. The contents of the array pointed to by buf is undefined on error.

ERRORS

       EACCES Permission to read or search a component of the file name was denied.

       EFAULT buf points to a bad address.

       EINVAL The size argument is zero and buf is not a null pointer.

       ENOENT The current working directory has been unlinked.

       ERANGE The size argument is less than the length of the working directory name.	You need to allocate a bigger array and try again.

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.

CONFORMING TO

       POSIX.1

SEE ALSO

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

GNU
								    2002-04-22								 GETCWD(3)