getlogin(3C)															      getlogin(3C)

NAME

       getlogin(), getlogin_r() - get name of user logged in on this terminal

SYNOPSIS

DESCRIPTION

       The  function  retrieves  the  name  of	the  user currently logged in on a terminal associated with the calling process, as found in user-
       accounting database maintained by utmpd(1M).

       At least one of the standard input, standard output, or standard error must be a terminal.  For the first of these found that is  a  termi-
       nal,  a	user must have logged in on that terminal, and that terminal must be the controlling terminal of the session leader process of the
       calling process's session.

       The function can be used in conjunction with to locate the correct password file entry when the same user ID is	shared	by  several  login
       names.

       The  recommended procedure to obtain the user name associated with the real user ID of the calling process is to call and if that fails, to
       call

       To get the user name associated with the effective user ID, call

       performs the same operations as but returns the login name in the buffer to which buf points, whose size  in  bytes  should  be	passed	in
       buflen.	 buf  should have space for the name and the terminating null character.  The maximum size of the login name can be obtained using
       the API with as the argument.

APPLICATION USAGE

       The return value from points to static data whose content is overwritten by each call.

RETURN VALUE

       Upon successfully finding and validating the login name of the user logged in on the terminal, returns a pointer to the	name.	Otherwise,
       it returns a null pointer, and sets to indicate the error.

       Upon  successfully finding, validating, and copying to the buffer the login name of the user logged in on the terminal, returns 0 upon suc-
       cess and returns an error number upon failure.

ERRORS

       and fail if any of the following is true:

	      [EACCES]	     Access permission to get the status of the terminal device file, was denied.

	      [EMFILE]	     Too many file descriptors are in use by this process.

	      [ENFILE]	     Too many file descriptors are in use on the system.

	      [ENOENT]	     The terminal device file cannot be found.

	      [ENOTTY]	     None of the standard input, standard output, or standard error is a terminal, or for the first of	these  that  is  a
			     terminal,	no  current login is registered on that terminal, or the session leader process of the calling process has
			     no controlling terminal.

	      [EPERM]	     One of the standard input, standard output, or standard error is a terminal, and a current login was  found  on  that
			     terminal, but that terminal is not the same as the controlling terminal of the session of the calling process.

	      [ESRCH]	     The session leader process of the calling process is no longer running.

       The  error condition associated with [EPERM] prevents processes that have access to some other user's terminal from believing that they are
       related to that other user's login session.

       also fails if the following is true:

	      [ERANGE]	     The length of the name to be returned, including the terminating null byte, exceeds buflen.

WARNINGS

       Users of should note now conforms with the POSIX.1c Threads standard.  The old prototype of is supported for  compatibility  with  existing
       DCE applications only.

SEE ALSO

       utmpd(1M), getuid(2), sysconf(2), getgrent(3C), getpwent(3C), thread_safety(5).

STANDARDS CONFORMANCE

																      getlogin(3C)