_service.md

Sample service script for debianoids

Look at LSB init scripts for more information.

Usage

Copy to /etc/init.d:

# replace "$YOUR_SERVICE_NAME" with your service's name (whenever it's not enough obvious)
cp "service.sh" "/etc/init.d/$YOUR_SERVICE_NAME"
chmod +x /etc/init.d/$YOUR_SERVICE_NAME

Edit the script and replace following tokens:

• <NAME> = $YOUR_SERVICE_NAME
• <DESCRIPTION> = Describe your service here (be concise)
• Feel free to modify the LSB header, I've made default choices you may not agree with
• <COMMAND> = Command to start your server (for example /home/myuser/.dropbox-dist/dropboxd)
• <USER> = Login of the system user the script should be run as (for example myuser)

Start and test your service:

service $YOUR_SERVICE_NAME start
service $YOUR_SERVICE_NAME stop

Install service to be run at boot-time:

update-rc.d $YOUR_SERVICE_NAME defaults

Enjoy

Uninstall

The service can uninstall itself with service $NAME uninstall. Yes, that's very easy, therefore a bit dangerous. But as it's an auto-generated script, you can bring it back very easily. I use it for tests and often install/uninstall, that's why I've put that here.

Don't want it? Remove lines 56-58 of the service's script.

Logs?

Your service will log its output to /var/log/$NAME.log. Don't forget to setup a logrotate :)

I'm noob and/or lazy

Yep, I'm lazy too. But still, I've written a script to automate this :)

wget 'https://raw.github.com/gist/4275302/new-service.sh' && bash new-service.sh

In this script I will download service.sh into a tempfile, replace some tokens, and then show you commands you should run as superuser.

If you feel confident enough with my script, you can sudo the script directly:

wget 'https://raw.github.com/gist/4275302/new-service.sh' && sudo bash new-service.sh

Note: the cool hipsterish curl $URL | bash won't work here, I don't really want to check why.

Demo

Creating the service:

Looking at service files (logs, pid):

Uninstalling service:

new-service.sh

#!/bin/bash

SERVICE_FILE=$(tempfile)

echo "--- Download template ---"
wget -q -O "$SERVICE_FILE" 'https://raw.github.com/gist/4275302/service.sh'
chmod +x "$SERVICE_FILE"
echo ""

echo "--- Customize ---"
echo "I'll now ask you some information to customize script"
echo "Press Ctrl+C anytime to abort."
echo "Empty values are not accepted."
echo ""

prompt_token() {
  local VAL=""
  while [ "$VAL" = "" ]; do
    echo -n "${2:-$1} : "
    read VAL
    if [ "$VAL" = "" ]; then
      echo "Please provide a value"
    fi
  done
  VAL=$(printf '%q' "$VAL")
  eval $1=$VAL
  sed -i "s/<$1>/$(printf '%q' "$VAL")/g" $SERVICE_FILE
}

prompt_token 'NAME'        'Service name'
if [ -f "/etc/init.d/$NAME" ]; then
  echo "Error: service '$NAME' already exists"
  exit 1
fi

prompt_token 'DESCRIPTION' ' Description'
prompt_token 'COMMAND'     '     Command'
prompt_token 'USERNAME'    '        User'
if ! id -u "$USERNAME" &> /dev/null; then
  echo "Error: user '$USERNAME' not found"
  exit 1
fi

echo ""

echo "--- Installation ---"
if [ ! -w /etc/init.d ]; then
  echo "You don't gave me enough permissions to install service myself."
  echo "That's smart, always be really cautious with third-party shell scripts!"
  echo "You should now type those commands as superuser to install and run your service:"
  echo ""
  echo "   mv \"$SERVICE_FILE\" \"/etc/init.d/$NAME\""
  echo "   touch \"/var/log/$NAME.log\" && chown \"$USERNAME\" \"/var/log/$NAME.log\""
  echo "   update-rc.d \"$NAME\" defaults"
  echo "   service \"$NAME\" start"
else
  echo "1. mv \"$SERVICE_FILE\" \"/etc/init.d/$NAME\""
  mv -v "$SERVICE_FILE" "/etc/init.d/$NAME"
  echo "2. touch \"/var/log/$NAME.log\" && chown \"$USERNAME\" \"/var/log/$NAME.log\""
  touch "/var/log/$NAME.log" && chown "$USERNAME" "/var/log/$NAME.log"
  echo "3. update-rc.d \"$NAME\" defaults"
  update-rc.d "$NAME" defaults
  echo "4. service \"$NAME\" start"
  service "$NAME" start
fi

echo ""
echo "---Uninstall instructions ---"
echo "The service can uninstall itself:"
echo "    service \"$NAME\" uninstall"
echo "It will simply run update-rc.d -f \"$NAME\" remove && rm -f \"/etc/init.d/$NAME\""
echo ""
echo "--- Terminated ---"

service.sh

#!/bin/sh
### BEGIN INIT INFO
# Provides:          <NAME>
# Required-Start:    $local_fs $network $named $time $syslog
# Required-Stop:     $local_fs $network $named $time $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Description:       <DESCRIPTION>
### END INIT INFO

SCRIPT=<COMMAND>
RUNAS=<USERNAME>

PIDFILE=/var/run/<NAME>.pid
LOGFILE=/var/log/<NAME>.log

start() {
  if [ -f /var/run/$PIDNAME ] && kill -0 $(cat /var/run/$PIDNAME); then
    echo 'Service already running' >&2
    return 1
  fi
  echo 'Starting service…' >&2
  local CMD="$SCRIPT &> \"$LOGFILE\" & echo \$!"
  su -c "$CMD" $RUNAS > "$PIDFILE"
  echo 'Service started' >&2
}

stop() {
  if [ ! -f "$PIDFILE" ] || ! kill -0 $(cat "$PIDFILE"); then
    echo 'Service not running' >&2
    return 1
  fi
  echo 'Stopping service…' >&2
  kill -15 $(cat "$PIDFILE") && rm -f "$PIDFILE"
  echo 'Service stopped' >&2
}

uninstall() {
  echo -n "Are you really sure you want to uninstall this service? That cannot be undone. [yes|No] "
  local SURE
  read SURE
  if [ "$SURE" = "yes" ]; then
    stop
    rm -f "$PIDFILE"
    echo "Notice: log file is not be removed: '$LOGFILE'" >&2
    update-rc.d -f <NAME> remove
    rm -fv "$0"
  fi
}

case "$1" in
  start)
    start
    ;;
  stop)
    stop
    ;;
  uninstall)
    uninstall
    ;;
  retart)
    stop
    start
    ;;
  *)
    echo "Usage: $0 {start|stop|restart|uninstall}"
esac