My "Bread and Butter" Process Keep Alive Perl Script.... Post: 302883288

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Top Forums UNIX for Beginners Questions & Answers Answers to Frequently Asked Questions Tips and Tutorials My "Bread and Butter" Process Keep Alive Perl Script.... Post 302883288 by MadeInGermany on Monday 13th of January 2014 05:33:45 AM

01-13-2014

Registered User

Now the haute cuisine:
a shell daemon that polls /proc every 30 seconds:

Code:

#!/bin/bash

# name of the daemon to watch
pname=named
pstart=/usr/sbin/$pname

# this script
me=${0##*/}
# e.g. me=named_watcher.sh

export PATH=/bin:/usr/bin:/usr/sbin:/sbin

# sh sends SIGHUP on exit, we need to continue
trap 'echo "SIGHUP captured"' HUP

# no interactions, log all output and errors
mkdir -p /var/log
exec </dev/null >/var/log/${me%.*}.log 2>&1

# Solaris needs -z option
zopt=`{ zonename; } 2>/dev/null`
zopt=${zopt:+"-z $zopt"}

echo "$me started with pid $$"
sleep 3
# initiate the pid variables
pid=`pgrep $zopt -x $pname`
[ -n "$pid" ] || exec echo "no $pname process - exiting"
echo "$me watching $pname[$pid]"

# endless loop
while :
do
 sleep 30
 if [ \! -d /proc/$pid ]; then
  echo "`date` $me $pid is gone!"
  sleep 1
  echo "starting $pname"
  date
  eval $pstart
  sleep 3
  # renew the pid variables
  pid=`pgrep $zopt -x $pname`
  [ -n "$pid" ] || exec echo "no $pname process - exiting"
  echo "$me watching $pname[$pid]"
 fi
done

The script should be background-started (with &) in the start section of the process (here: named) init script, *after* the process is started.
And killed in the stop section of the process start script, *before* the process is killed.

Last edited by MadeInGermany; 01-13-2014 at 03:46 PM..

MadeInGermany

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LEARN ABOUT DEBIAN

bcrontab

bcrontab(1)						      General Commands Manual						       bcrontab(1)

NAME

       bcrontab - Manage users crontab files

SYNOPSIS

       bcrontab [ -u user ] file

       bcrontab [ -u user ] { -l | -r | -e }

DESCRIPTION

       bcrontab interfaces with the bcron-spool daemon to manage crontab files in the privileged spool directory.

OPTIONS

       -u user
	      Tell  bcron-spool  that we are acting on behalf of the named user.  bcron-spool will only accept the username if bcrontab is running
	      as either root or the same user ID as the named user.

       -l     List the cronab crontab to standard output.

       -r     Remove the user's crontab.

       -e     Edit the current crontab.

ENVIRONMENT

       VISUAL If this is set, it is used as the editor to invoke to edit a crontab.

       EDITOR If $VISUAL is not set and this is, it is used as the editor to invoke to edit a crontab.	If neither are set, /bin/vi is used.

       BCRON_SOCKET
	      The path to the named socket used to communicate with bcron-spool.  Defaults to /var/run/bcron-spool.

       LOGNAME

       USER   These two variables are used, in order, to determine the user name invoking the program.	One must be set if the -u  option  is  not
	      used.

FILES

       bcrontab  tries	to  writes  a  temporary  file	into the current directory, and then into /tmp if that fails, in order to edit the current
       crontab.

SEE ALSO

       bcron-spool(8), crontab(5)

AUTHOR

       Bruce Guenter <bruceg@em.ca>

																       bcrontab(1)