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Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ll-xn!mit-eddie!uw-beaver!apollo!mrst!sdti!mjy
From: mjy@sdti.UUCP (Michael J. Young)
Newsgroups: comp.unix.wizards,comp.unix.xenix
Subject: Re: multi/single-user mode flag?
Keywords: What number?
Message-ID: <268@sdti.UUCP>
Date: 18 May 88 15:21:00 GMT
References: <3595@psuvax1.psu.edu> <243@oha.UUCP> <340@conexch.UUCP> <166@ofc.Columbia.NCR.COM>
Reply-To: mjy@sdti.UUCP (0000-Michael J. Young)
Organization: Software Development Technologies, Sudbury MA
Lines: 43

In article <166@ofc.Columbia.NCR.COM> rogers@ofc.UUCP (H. L. Rogers) writes:
>In article <340@conexch.UUCP> root@conexch.UUCP (Larry Dighera) writes:
>>The normal way for a Sys V user to determine which run level state the system 
>>is in, is to do a 'who -r'.
>True, but since there is no 'standard' which specifies the system state for
>a particular run level number, a user program (application?) risks
>portability problems from vendor to vendor.  Does anyone know of any
>standards work to abstract the numerical run level for Un*x systems?

I don't know of a standard way, but this should work for System V at least.
No flames for style or accuracy.  Not a shar.
--------------------- cut here ---------------- cut here -------------------
# include <stdio.h>
# include <sys/types.h>
# include <utmp.h>

extern struct utmp *getutid ();
extern void utmpname ();

int main (){
	struct utmp *buf;	/* will hold utmp entry */
	struct utmp buf2;	/* dummy entry to hold search type */

	/*
	 * look for an entry in the utmp file that is of type RUN_LVL.
	 * The ut_line member of this entry will contain the string 
	 * "run-level %c", where %c is [sS1-6].
         */
	buf2.ut_type = RUN_LVL;
	utmpname ("/etc/utmp");	/* not really necessary */
	if ((buf = getutid (&buf2)) == NULL){
		perror ("rlvl: could not find RUN_LVL entry in /etc/utmp");
		exit (1);
	}
	else {
		printf ("%c\n", buf->ut_line[10]);
	}
	exit (0);
}
-- 
Mike Young - Software Development Technologies, Inc., Sudbury MA 01776
UUCP     : {decvax,harvard,linus,mit-eddie}!necntc!necis!mrst!sdti!mjy
Internet : mjy%sdti.uucp@harvard.harvard.edu      Tel: +1 617 443 5779
"Bill & Opus in '88" -- Consider the alternatives!