gistfile1.txt

#!/usr/bin/env bash

set -euxo pipefail

# constants definition
LOGFILE="/var/log/ss-monitor.log"
TARGET_SERVICE="shadowsocks-libev"

log() {
        printf '[%s] %s\n' "$(date -Is)" "$@" >> $LOGFILE
}

getprop() {
        systemctl show "$TARGET_SERVICE" -P "$1"
}

# check systemd for process status
pid="$(getprop 'MainPID')"
if test "$pid" -eq 0; then # according to systemd docs 0 means dead.
        # service has died, gather some more data
        diedat="$(getprop 'ExecMainExitTimestamp')"
        log "ERRO: service $TARGET_SERVICE has died at ${diedat}."
else
        # service is running, all good
        log "INFO: service $TARGET_SERVICE is running. (pid: ${pid})"
fi

ss-monitor.service

[Service]
ExecStart=/opt/ss-monitor.sh

ss-monitor.timer

[Timer]
OnCalendar=*:*:0/30
Persistent=true

[Install]
WantedBy=multi-user.target