GETLOGIN(2)	    UNIX Programmer's Manual	      GETLOGIN(2)


NAME
     getlogin, setlogin - get/set login name

SYNOPSIS
     #include <unistd.h>

     char *
     getlogin()

     int
     setlogin(name)
	  char *name;

DESCRIPTION
     The getlogin routine returns the login name of the user
     associated with the current session, as previously set by
     setlogin.	The name is normally associated with a login
     shell at the time a session is created, and is inherited by
     all processes descended from the login shell.  (This is true
     even if some of those processes assume another user ID, for
     example when su(1) is used.)

     Setlogin sets the login name of the user associated with the
     current session to name.  This call is restricted to the
     super-user, and is normally used only when a new session is
     being created on behalf of the named user (for example, at
     login time, or when a remote shell is invoked).

RETURN VALUES
     If a call to getlogin succeeds, it returns a pointer to a
     null-terminated string in a static buffer.  If the name has
     not been set, it returns NULL.  If a call to setlogin
     succeeds, a value of 0 is returned.  If setlogin fails, a
     value of -1 is returned and an error code is placed in the
     global location errno.

ERRORS
     The following errors may be returned by these calls:

     EFAULT	    The name parameter gave an invalid address.

     EINVAL	    The name parameter pointed to a string that
		    was too long.  Login names are limited to
		    MAXLOGNAME (from <sys/param.h>) characters,
		    currently 16.

     EPERM	    The caller tried to set the login name and
		    was not the super-user.

SEE ALSO
     setsid(2)


Printed 11/26/99       September 23, 1997			1


GETLOGIN(2)	    UNIX Programmer's Manual	      GETLOGIN(2)


BUGS
     Login names are limited in length by setlogin.  However,
     lower limits are placed on login names elsewhere in the sys-
     tem (UT_NAMESIZE in <utmp.h>).

     In earlier versions of the system, getlogin failed unless
     the process was associated with a login terminal.	The
     current implementation (using setlogin) allows getlogin to
     succeed even when the process has no controlling terminal.
     In earlier versions of the system, the value returned by
     getlogin could not be trusted without checking the user ID.
     Portable programs should probably still make this check.

HISTORY
     The setlogin function first appeared in 4.4BSD.  The getlo-
     gin function was present in V7.


Printed 11/26/99       September 23, 1997			2


 
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