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

NAME
       getcwd, getwd, getcurrentdirname - get current working directory

SYNOPSIS
       #include 

       char *getcwd(char *buf, sizet size);

       char *getwd(char *buf);

       char *getcurrentdirname(void);

   Feature Test Macro Requirements for glibc (see featuretestmacros(7)):

       getcurrentdirname():
              GNUSOURCE

       getwd():
           Since glibc 2.12:
               BSDSOURCE ||
                   (XOPENSOURCE >= 500 ||
                       XOPENSOURCE && XOPENSOURCEEXTENDED) &&
                   !(POSIXCSOURCE >= 200809L || XOPENSOURCE >= 700)
           Before glibc 2.12:
               BSDSOURCE || XOPENSOURCE >= 500 ||
               XOPENSOURCE && XOPENSOURCEEXTENDED

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.

       getcurrentdirname()  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 PATHMAX bytes long.  If the length of the
       absolute pathname of the current working directory, including the  ter‐
       minating null byte, exceeds PATHMAX bytes, NULL is returned, and errno
       is set to ENAMETOOLONG.  (Note that on some systems, PATHMAX  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 PATHMAX 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.

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       ┌───────────────────────┬───────────────┬─────────────┐
       │Interface              │ Attribute     │ Value       │
       ├───────────────────────┼───────────────┼─────────────┤
       │getcwd(), getwd()      │ Thread safety │ MT-Safe     │
       ├───────────────────────┼───────────────┼─────────────┤
       │getcurrentdirname() │ Thread safety │ MT-Safe env │
       └───────────────────────┴───────────────┴─────────────┘
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().

       getcurrentdirname() 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)