Man Getwd en anglais
GETCWD(3)                  Linux Programmer's Manual                 GETCWD(3)



 

NAME


       getcwd, getwd, get_current_dir_name - Get current working directory

 

SYNOPSIS


       #include 

       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






       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  current  absolute  pathname 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 behavior of getcwd() is undefined.

       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 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(3) the buffers if  they
       have been obtained this way.

       get_current_dir_name(),  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(),  does  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 file
       system  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 filename 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  direc-
              tory name.  You need to allocate a bigger array and try again.

 

CONFORMING TO


       getcwd() conforms to POSIX.1-2001.  getwd() is present in POSIX.1-2001,
       but marked LEGACY.  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 3.05 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                               2007-07-26                         GETCWD(3)