Date: Fri, 11 May 2001 12:35:21 -0500 From: Dan Nelson <dnelson@emsphone.com> To: Michael Lucas <mwlucas@blackhelicopters.org> Cc: questions@FreeBSD.ORG Subject: Re: syslog.conf && executing programs Message-ID: <20010511123521.A2528@dan.emsphone.com> In-Reply-To: <20010511110227.A27757@blackhelicopters.org>; from "Michael Lucas" on Fri May 11 11:02:27 GMT 2001 References: <20010511110227.A27757@blackhelicopters.org>
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In the last episode (May 11), Michael Lucas said:
> I'd like to use syslogd to mail me upon certain events.
>
> local3.* | /usr/bin/mail -s alert mwlucas
>
> The first time something is appended to the log, I get a mail.
>
> The second time, I get a hang:
>
> loghost/etc;ps -ax | grep mail
> 25711 ?? Is 0:00.00 sh -c /usr/bin/mail -s alert mwlucas
> 25712 ?? I 0:00.00 /usr/bin/mail -s alert mwlucas loghost/etc;
For efficiency, syslogd treats the program as a pipe; it will spawn it
once, then send log entries one line at a time as they come in. The
child process will be killed after 60 seconds of idle time.
Excerpt from syslog.conf manpage:
So if it is desired that the subprocess should get exactly one line
of input only (which can be very resource-consuming if there are a
lot of messages flowing quickly), this can be achieved by exiting
after just one line of input. If necessary, a script wrapper can
be written to this effect.
--
Dan Nelson
dnelson@emsphone.com
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