Date: Mon, 24 Nov 2003 10:51:18 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: freebsd-questions@FreeBSD.ORG Subject: Re: daemon monitoring Message-ID: <20031124105118.GA14538@happy-idiot-talk.infracaninophile.co.uk> In-Reply-To: <20031124011921.GC96651@users.munk.nu> References: <3B75ECFD-1DE6-11D8-A141-000A95DBBE34@mercurycloud.net> <20031123215725.GC557@dds.nl> <98017B2C-1E17-11D8-A141-000A95DBBE34@mercurycloud.net> <20031124011139.GA60027@dds.nl> <20031124011921.GC96651@users.munk.nu>
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On Mon, Nov 24, 2003 at 01:19:21AM +0000, Jez Hancock wrote:
> - for each pid, send a CHLD signal to the pid
Careful -- not all processes will be set up to deal with SIGCHLD, and
some of them will be set up to deal with it in ways that don't meet
your expectations.
You can use signal '0' to test if a process of a given PID exists,
without obnoxious side effects:
% kill -0 $$
% echo $?
0
% kill -0 999
999: No such process
% echo $?
1
However you need to be careful as kill is a shell built-in in many
shells -- tcsh(1) has a built-in but it behaves just like /bin/kill in
this case. sh(1) and bash(1) seem not to use a built-in.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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