getcwd

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)):

       getcwd(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
       get_current_dir_name(): _GNU_SOURCE

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  work-
       ing directory to the array pointed to by buf, which is of length size.

       If  the  length  of the absolute pathname of the current working direc-
       tory, 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 ter-
       minating 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.

       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  path-
              name  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 3.23 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                               2009-03-31                         GETCWD(3)