Path: utzoo!utgpu!attcan!uunet!vsedev!logan
From: logan@vsedev.VSE.COM (James Logan III)
Newsgroups: comp.unix.questions
Subject: Re: Login shell?
Message-ID: <1230@vsedev.VSE.COM>
Date: 7 Nov 88 23:55:16 GMT
References: <3ed799bc.103e8@hi-csc.UUCP> <13851@mimsy.UUCP> <511@imec.UUCP> <25721@bu-cs.BU.EDU> <10791@ulysses.homer.nj.att.com> <1217@vsedev.VSE.COM> <1623@solo10.cs.vu.nl>
Reply-To: logan@vsedev.VSE.COM (James Logan III)
Organization: VSE Software Development Lab
Lines: 41

In article <1623@solo10.cs.vu.nl> maart@cs.vu.nl (Maarten Litmaath) writes:
>In article <1217@vsedev.VSE.COM> logan@vsedev.VSE.COM (James Logan III) writes:
>\... If you just want to find out what if the current
>\shell is indeed the shell spawned by init(1M) (via getty(1M), login(1)),
>\then just write a simple C program like this:
>\--------
>\#include <stdio.h>
>\
>\main()
>\{
>\	if (getppid() == getpgrp())
>\		exit(0);
>\	exit(1);
>\}
>
>1)
>	Why #include <stdio.h>?

It's not necessary, I just always need it when I don't already have it,
so it's just a habit, I guess.  It doesn't hurt anything and it will only
take a fraction of a second longer to compile it.  In addition, if he
adds an fprintf(), the program won't compile without it since the
type "FILE" will be undefined.

I wouldn't suggest #including every header file you might ever need,
but this one is so often used, why not?

>2)
>	This scheme won't work for rsh/rlogin.

It works just fine for rlogin, thank you.  I just tested it on my
system.  

Since you don't have a true session with rsh it will indicate
correctly that the program running is not your login shell.  

			-Jim
-- 
Jim Logan		logan@vsedev.vse.com
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