I suppose you may say all of this can be just as easily be done via systemd service config files. Well, yes and no. Yes, it can be done. And, no, not as easily. Not even close. Because systemd sucks by design. But this is a subject for another post. For now, here’s just yet another lazy sysadmin’s scripted shortcut.

The script below will get a list of enabled services. It will then figure out which of those are not running and restart them (unless you added them to the exclude list in the script). An entry will be added to the log and you’ll get an email as well.

So nothing fancy, just a quick and dirty way to bounce dead services without getting into why they died in the first place. A bit like fixing your ceiling over and over while your roof is leaking. You can get this script from my GitHub repo as well.

#!/bin/bash
#
#                                      |
#                                  ___/"\___
#                          __________/ o \__________
#                            (I) (G) \___/ (O) (R)
#                                   Igor Os
#                           igor@comradegeneral.com
#                                 2019-08-08
# ----------------------------------------------------------------------------
# Identify active system services that are not running and restart them.
# Tested with RHEL/CentOS 7
#
# Documentation URL: https://
#
# CHANGE CONTROL
# ----------------------------------------------------------------------------
# 2019-08-08  igor wrote this script
# ----------------------------------------------------------------------------

function func_configure() {
  # A list of services that should not be restarted even if they're not running
  exclude="rhel|abrt|mdmonitor|microcode|raid|systemd|ntpd|chrony"
  tmpfile="$(mktemp)"
  #
  this_host="$(hostname | awk -F. '{print $1}')"
  this_script=$(basename "$(test -L "$0" && readlink "$0" || echo "$0")")
  this_script_full="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/$(basename "${BASH_SOURCE[0]}")"
  this_time_db=$(date +'%Y-%m-%d %H:%M:%S')
  this_time_epoch=$(date -d "${this_time_db}" '+%s')
  this_time=$(date -d "${this_time_db}" +'%Y-%m-%d_%H:%M:%S')
  #
  logdirbase="/var/log"
  logdir="${logdirbase}/${this_script}"
  if [ ! -d "${logdir}" ]
  then
    /bin/mkdir -p "${logdir}" 2>/dev/null || exit 100
  fi
  logfile="${logdir}/${this_script}.log"
  if [ ! -f "${logfile}" ]
  then
    /bin/touch "${logfile}" || exit 110
  fi
  #
  mail_subject="${this_host} generated an event at ${this_time}"
  mail_recipients="you@domain.com"
}

function func_systemctl_check() {
  /bin/systemctl 2>/dev/null 1>&2; echo $?
}

function func_service_check() {
  if [ $(func_systemctl_check) -eq 0 ]
  then
    /bin/systemctl list-unit-files | grep enabled | grep -Ev "${exclude}" | awk '{print $1}' | while read i
    do
      s="$(/bin/systemctl status ${i} 2>/dev/null | grep -oP "(?<=Active: )[a-z]{1,}(?= )")"
      if [ ! -z "${s}" ]
      then
        echo -e "${i}\t${s}"
      fi
    done | column -t | sort -k2r
  fi
}

function func_service_dead() {
  if [ $(func_systemctl_check) -eq 0 ]
  then
    func_service_check | grep inactive | awk '{print $1}'
  fi
}

function func_service_restart() {
  if [ $(func_systemctl_check) -eq 0 ]
  then
    j=0; echo "${j}" > "${tmpfile}"
    func_service_dead | while read i
    do
      (( j = j + 2 )); echo "${j}" > "${tmpfile}"
      echo "Restarting dead ${i}" | tee -a "${logfile}"
      /bin/systemctl restart "${i}" 2>/dev/null
      sleep 3
      s="$(/bin/systemctl status ${i} 2>/dev/null | grep -oP "(?<=Active: )[a-z]{1,}(?= )")"
      echo "New status of ${i} is: ${s}" | tee -a "${logfile}"
    done
    j="$(head -1 "${tmpfile}")"
    if [ ${j} -gt 0 ]
    then
      tail -${j} "${logfile}" | mailx -s "${mail_subject}" "${mail_recipients}"
    fi
  fi
}

# ----------------------------------------------------------------------------
# RUNTIME
# \(^_^)/                                      __|__
#                                     __|__ *---o0o---*
#                            __|__ *---o0o---*
#                         *---o0o---*
# ----------------------------------------------------------------------------
func_configure
func_service_restart