/etc/init.d/zramswap for system without upstart

#! /bin/sh
#
# zramswap - Script to setup zramswap.
# based on atftpd and zramswap-enabler.
#
### BEGIN INIT INFO
# Provides:          atftpd
# Required-Start:    $syslog $network $remote_fs
# Required-Stop:     $syslog $network $remote_fs
# Should-Start:      $local_fs
# Should-Stop:       $local_fs
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Setup zramswap
# Description:       Setup zramswap, to compress memory.
### END INIT INFO

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
NAME=zramswap
DESC="zram swapping"
OPTIONS=""

set -e

# get the number of CPUs
num_cpus=$(grep -c processor /proc/cpuinfo)
# if something goes wrong, assume we have 1
[ "$num_cpus" != 0 ] || num_cpus=1
# set decremented number of CPUs
decr_num_cpus=$((num_cpus - 1))
# get the amount of memory in the machine
mem_total_kb=$(grep MemTotal /proc/meminfo | grep -E --only-matching '[[:digit:]]+')
mem_total=$((mem_total_kb * 1024))

case "$1" in
  start)
        echo -n "Starting $DESC: "
        # load dependency modules
        modprobe zram zram_num_devices=$num_cpus

        # initialize the devices
        for i in $(seq 0 $decr_num_cpus); do
        echo $((mem_total / num_cpus)) > /sys/block/zram$i/disksize
        done

        # Creating swap filesystems
        for i in $(seq 0 $decr_num_cpus); do
        mkswap /dev/zram$i
        done

        # Switch the swaps on
        for i in $(seq 0 $decr_num_cpus); do
        swapon -p 100 /dev/zram$i
        done
        echo "$NAME."
        ;;
  stop)
        echo -n "Stopping $DESC: "
        # Switching off swap
        for i in $(seq 0 $decr_num_cpus); do
        if [ "$(grep /dev/zram$i /proc/swaps)" != "" ]; then
        swapoff /dev/zram$i
        fi
        done

        rmmod zram
        echo "$NAME."
        ;;
  restart|reload|force-reload)
        /etc/init.d/zramswap stop
        sleep 1
        /etc/init.d/zramswap start
        ;;
  *)
        N=/etc/init.d/$NAME
        echo "Usage: $N {start|stop|restart|reload|force-reload}" >&2
        exit 1
        ;;
esac

exit 0