Hi Patrick,
On Tue, Jan 28, 2020 at 09:29:20AM +0100, Patrick Kristiansen wrote:
| Hi Ingo
|
| Thank you for your reply.
|
| I can't say I disagree with your and the OpenBSD team's attitude about
| bug-free daemons. But I am just a lowly application programmer, and
| sometimes I introduce horrible bugs that make our systems crash. In many
| cases it will be preferable to just start the process again (and, of
| course, fix the bug) for the purposes of keeping our business running.
|
| But another use for daemon(8) is for its ability to detach the child
| process from the controlling terminal and furthermore redirect its
| stdout/stderr to syslog. Is there some mechanism to do that from the
| shell? Perhaps a combination of nohup and starting a background job?
What I do to run a "normal" (non-daemon) program like a daemon, is to
start it in tmux. To have this start during system startup, I have an
@reboot cronjob:
----------------------------------------------------------------------
[weerd@cube] $ cat ~/bin/conlog
#!/bin/sh
# conlog: start a tmux session with cu logging to a file
######################################################################
# Can be used with the following @reboot cron line to start at boot:
#
# @reboot /home/weerd/bin/conlog
PATH=/bin:/usr/bin
LOG="/home/weerd/data/conlog/log.`date +%s`"
mkdir -p `dirname ${LOG}`
tmux new -d "script -c 'cu -l cuaU0 -s 115200' ${LOG}"
----------------------------------------------------------------------
At reboot, this will start a new (detached) tmux session that launches
cu (under script) to log the serial console output from another
OpenBSD machine. I can attach the tmux session and interact with the
console of that machine if necessary.
For the purpose of restarting crashing programs, you could do
something similar: run your program in a tmux session (convenient to
attach to when you want to look at its stdout/stderr output) and
script something to restart when it errors out. You could then also
send yourself e-mail to alert you to the restart.
Cheers,
Paul 'WEiRD' de Weerd
--
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