Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!caip!ut-sally!seismo!umcp-cs!mark
From: mark@umcp-cs.UUCP (Mark Weiser)
Newsgroups: net.unix-wizards,net.unix
Subject: Re: which is my login terminal
Message-ID: <2222@umcp-cs.UUCP>
Date: Mon, 30-Jun-86 23:13:24 EDT
Article-I.D.: umcp-cs.2222
Posted: Mon Jun 30 23:13:24 1986
Date-Received: Wed, 2-Jul-86 03:22:49 EDT
References: <34@gec-rl-hrc.co.uk>
Reply-To: mark@maryland.UUCP (Mark Weiser)
Organization: University of Maryland, Dept. of Computer Sci.
Lines: 20
Xref: watmath net.unix-wizards:18683 net.unix:8469

In article <34@gec-rl-hrc.co.uk> nwh@gec-rl-hrc.co.uk (Nigel Holder Marconi) writes:
>
>   I have an application that needs to know whether I am logged
>on at the console to decide whether I can paint all over the
>sun bit-mapped screen.  I could be in suntools, a pty (either via
>suntools, remote login or any windowing system), the normal console,
>device, or an external port (eg. ttya).  What I really need to know
>is whether I actually logged in at the console for this session.
>As other people might want to run the application the solution must
>be general.  If I'm not on a pty then it is possible to use ttyname().

There is no sure fire method, but one I use is: check ttyname(0)
(i.e. of the file descripter underlying stdin).  If it is /dev/console,
assume you DO have screen access.  If that is not
/dev/console, then check for the existence of the WINDOW_GFX environment
variable.  If it is not set, assume you do not have screen access.
-- 
Spoken: Mark Weiser 	ARPA:	mark@maryland	Phone: +1-301-454-7817
CSNet:	mark@umcp-cs 	UUCP:	{seismo,allegra}!umcp-cs!mark
USPS: Computer Science Dept., University of Maryland, College Park, MD 20742