Subject: Re: serial line ideas
To: Phil Knaack <email@example.com>
From: Curt Sampson <firstname.lastname@example.org>
Date: 11/15/1996 12:07:06
On Fri, 15 Nov 1996, Phil Knaack wrote:
> One of the common ways to determine if a PID exists is to send
> it a signal 0 .. signal 0 just bounces off the process without any effect;
> if the process doesn't exist, you get ESRCH.
> However, even sending a signal 0 is subject to the process's
> credentials, and a UUCP-owned process sending signal 0 to a non-UUCP
> process will return EPERM.
Which is fine, BTW. If you get ESRCH, you know the process doesn't
exist; if you get EPERM or no error, you know it does exist. This
is how I coded it, and uucp has to trouble determining whether the
lock is `alive' or not.
Curt Sampson email@example.com Info at http://www.portal.ca/
Internet Portal Services, Inc.
Vancouver, BC (604) 257-9400 De gustibus, aut bene aut nihil.