Some if-then-else-case examples

# If process not exist
if [ `ps ax|grep squid|grep -v grep|wc -l` = 0 ]; then
    echo "Squid is down. Starting"
    /usr/local/squid/sbin/squid
fi
#-=-=-=-=-=-=-=-=-
if [ ! `pgrep -f "memcached.*128" >/dev/null` ];then /usr/sbin/memcached; fi
#-=-=-=-=-=-=-=-=-
pgrep -f "memcached.*128" >/dev/null || /usr/sbin/memcached

# If file exist
zpid=/var/tmp/zabbix_agentd.аpid
if [ -f $zpid ]; then
    rm -f $zpid
fi

# If variable is empty:
if [ -z ${HOSTS} ]
# If variable found:
if [[ "${PREPARING_COMMAND}" ]]

# If 1 OR 2
if [ -z ${HOSTS[$i]#*:} ] || [ ${HOSTS[$i]#*:} == "ALL" ]
# If 1 AND 2
if (( $time >= 8 )) && (( $time <= 12 ))

# If substring found
msg="test test PROBLEM asd asd"
if [[ "$msg" == *PROBLEM* ]]
then
       echo bla
fi


# Case
case "$1" in
  start)
        echo "Starting"
        ;;
  stop)
        echo "Stopping"
        ;;
  reload)
        ;;
  restart|force-reload)
        echo "Restarting"
        ;;
  *)
        echo "Usage: $0 {start|stop|status|try-restart|restart|force-reload|reload}" >&2
        ;;
esac