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-account‐
       ing 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 terminal, 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 buf‐
       fer 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 overwrit‐
       ten 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 termi‐
			     nal 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  sys‐
			     tem.

	      [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 con‐
			     trolling 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)

Vote for polarhome