Provided by: manpages-dev_3.27-1ubuntu2_all bug

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 3.27 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/.