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I need some linux / ubuntu help:

I have a HTTP Comet server that I run with the following command:

$ node comet.js > /dev/null &

The > /dev/null bit is so all output is "shredded", and the ampersand is to run the task in the background.

How can I possibly run this command at linux startup?

I tried adding a script to /etc/init.d/node and then adding it to runtime using "update-rc.d node defaults", however for some reason the boot process then hung on startup with the output of the "node /path/to/comet.js" command.

I have the feeling that there is a better way to daemonize this process. How would I do this? Can anyone clear this up for me and explain to me some of the options that I have to start this script reliably?

Thanks, your help is really appreciated. Best, Chris

Here's my /etc/init.d/node:

#! /bin/sh
### BEGIN INIT INFO
# Provides:          node.js comet server
# Required-Start:    $remote_fs
# Required-Stop:     $remote_fs
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Example initscript
# Description:       This file should be used to construct scripts to be
#                    placed in /etc/init.d.
### END INIT INFO

# Author: Foo Bar <foobar@baz.org>
#
# Please remove the "Author" lines above and replace them
# with your own name if you copy and modify this script.

# Do NOT "set -e"

# PATH should only include /usr/* if it runs after the mountnfs.sh script
PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/bin/node
DESC="Node.js comet server"
NAME=node
DAEMON="/usr/local/bin/node"
DAEMON_ARGS="/home/chris/sites/www/comet/comet.js > /dev/null &"
PIDFILE=/var/run/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME

#
# Function that starts the daemon/service
#
do_start()
{
    # Return
    #   0 if daemon has been started
    #   1 if daemon was already running
    #   2 if daemon could not be started
    start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \
        || return 1
    start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON -- \
        $DAEMON_ARGS \
        || return 2
    # Add code here, if necessary, that waits for the process to be ready
    # to handle requests from services started subsequently which depend
    # on this one.  As a last resort, sleep for some time.
}

#
# Function that stops the daemon/service
#
do_stop()
{
    # Return
    #   0 if daemon has been stopped
    #   1 if daemon was already stopped
    #   2 if daemon could not be stopped
    #   other if a failure occurred
    start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 --pidfile $PIDFILE --name $NAME
    RETVAL="$?"
    [ "$RETVAL" = 2 ] && return 2
    # Wait for children to finish too if this is a daemon that forks
    # and if the daemon is only ever run from this initscript.
    # If the above conditions are not satisfied then add some other code
    # that waits for the process to drop all resources that could be
    # needed by services started subsequently.  A last resort is to
    # sleep for some time.
    start-stop-daemon --stop --quiet --oknodo --retry=0/30/KILL/5 --exec $DAEMON
    [ "$?" = 2 ] && return 2
    # Many daemons don't delete their pidfiles when they exit.
    rm -f $PIDFILE
    return "$RETVAL"
}

#
# Function that sends a SIGHUP to the daemon/service
#
do_reload() {
    #
    # If the daemon can reload its configuration without
    # restarting (for example, when it is sent a SIGHUP),
    # then implement that here.
    #
    start-stop-daemon --stop --signal 1 --quiet --pidfile $PIDFILE --name $NAME
    return 0
}

case "$1" in
  start)
    [ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$NAME"
    do_start
    case "$?" in
        0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
        2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
    esac
    ;;
  stop)
    [ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$NAME"
    do_stop
    case "$?" in
        0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
        2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
    esac
    ;;
  #reload|force-reload)
    #
    # If do_reload() is not implemented then leave this commented out
    # and leave 'force-reload' as an alias for 'restart'.
    #
    #log_daemon_msg "Reloading $DESC" "$NAME"
    #do_reload
    #log_end_msg $?
    #;;
  restart|force-reload)
    #
    # If the "reload" option is implemented then remove the
    # 'force-reload' alias
    #
    log_daemon_msg "Restarting $DESC" "$NAME"
    do_stop
    case "$?" in
      0|1)
        do_start
        case "$?" in
            0) log_end_msg 0 ;;
            1) log_end_msg 1 ;; # Old process is still running
            *) log_end_msg 1 ;; # Failed to start
        esac
        ;;
      *)
        # Failed to stop
        log_end_msg 1
        ;;
    esac
    ;;
  *)
    echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload}" >&2
    exit 3
    ;;
esac

:
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1  
Chris, I'm trying to understand where you got the 'node' and 'comet' programs since those are types of servers as opposed to specific products ... but I'm having problems googling for it since the terms are so generic. Could you please provide some links to the source of the software? It does matter to help answer the question accurately. –  Karl Katzke Aug 20 '09 at 1:38
    
Please post the startup script (/etc/init.d/node) that you tried to make. –  Zoredache Aug 20 '09 at 1:52
    
Thanks Karl and Zoredache.. node is an evented HTTP server written on top of Google V8. tinyclouds.org/node= comet.js is the source of my comet/http server written for node. I posted my init.d script above. I used the ubuntu init.d skeleton as a guide. –  Chris Aug 20 '09 at 2:15
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3 Answers

Ok, I've been working on this for a while, and I finally got it working.

I ended up using the new Ubuntu "upstart" service. It's a replacement for the /etc/init.d system.

Here's how it worked for me:

I put a file in /etc/event.d that describes my process:

description "node.js comet server"
author      "Chris"

start on startup
stop on shutdown
exec /usr/local/bin/node /path/to/comet.js > /dev/null &
respawn

Then I restarted, and it worked! Much better and easier than writing /etc/init.d scripts!

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This is totally a shot in the dark, because I'm not familiar with Ubuntu's start-stop-daemon, but maybe it's already doing the STDIN/STDOUT/STDERR redirection and job control? It's easy enough to test - just remove the " > /dev/null &" off the back end of $DAEMON_ARGS.

share|improve this answer
    
Ok I'll test that. I'm doing some tinkering with it right now. The last solution I posted actually doesn't work yet, it's missing all the LSB stuff; so I'm working on that now. Thanks Justin. :) –  Chris Aug 20 '09 at 3:02
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Here's the init.d script I use on a daily basis to monitor node.js servers on Debian. It should work "as is" on Ubuntu. It's versatile enough to enable a sysadmin to run multiple node instances under different usernames at startup

usage: /etc/init.d/MyNodejsServer.sh start|stop|restart|status

#! /bin/sh
# ------------------------------------------------------------------------------ 
# SOME INFOS : fairly standard (debian) init script.
#                 Note that node doesn't create a PID file (hence --make-pidfile) 
#                 has to be run in the background (hence --background)
#                 and NOT as root (hence --chuid)
#
# MORE INFOS :  INIT SCRIPT       http://www.debian.org/doc/debian-policy/ch-opersys.html#s-sysvinit
#               INIT-INFO RULES   http://wiki.debian.org/LSBInitScripts
#               INSTALL/REMOVE    http://www.debian-administration.org/articles/28
# ------------------------------------------------------------------------------
#                                                                              #
#                     BEGIN <MODIFY TO REFLECT YOUR SETTINGS>                  #
#                                                                              #
#
#  1) Don't forget to also modify the COMMENTED fields in the "### BEGIN INIT INFO"
#     below (don't uncomment them) if you wish to install system-wide with update-rc.d
#     eg: provides, Short-Description, Description
#
#  2) in case you have different node.js servers running, each init.d script should
#     (obviously) have a UNIQUE BASE name so that PIDS do not conflict
#     --> name them accordingly
#     eg: node_static_server, node_express1, node_load_balancer.sh...
#
#  3) copy the renamed/modified script(s) to /etc/init.d
#     chmod 755,
#
#  4) if you wish the Daemon to be lauched at boot / stopped at shutdown :
#     INSTALL : update-rc.d scriptname defaults 
#     (UNINSTALL : update-rc.d -f  scriptname remove)
#
#  5)  based on : Debian /etc/init.d/skeleton
#      modified by : Peter Host (www.oghme.com)
# ______________________________________________________________________________ 
### BEGIN INIT INFO
# Provides:          node_debian_init
# Required-Start:    $remote_fs $named $syslog
# Required-Stop:     $remote_fs $named $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: DEBIAN initscript for node.js servers/apps
# Description:       ex : proxy server is a node.js http server listening on
#                    port 8080 (relayed from 80 by iptables). It balances
#                    http requests between the main nodejs server 
#                    (nodejs.mydomain.com:8000), the static file-server 
#                    (static.mydomain.com) and the legacy apache server
#                    (apache.mydomain.com) and possibly other servers
#                    place this file in /etc/init.d.
### END INIT INFO

# Author: My Name <myname@domain.tld>
#
# Please remove the "Author" lines above and replace them
# with your own name if you copy and modify this script.
# ______________________________________________________________________________ 
#
# PATH should only include /usr/* if it runs after the mountnfs.sh script
PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/bin # modify if you need

DAEMON_ARGS="/path/to/app.js"               # path to your node.js server/app
                                            # NB: don't use ~/ in path

DESC="node.js http server"                  # whatever fancy description you like

NODEUSER=myuser:mygroup                     # USER who OWNS the daemon process (no matter whoever runs the init script)
                                            # user:group (if no group is specified, the primary GID for that user is used)

LOCAL_VAR_RUN=/usr/local/var/run            # in case the init script is run by non-root user, you need to
                                            # indicate a directory writeable by $NODEUSER to store the PID file
                                            # NB : 1) /usr/local/var/run does not exist by DEFAULT. Either create it
                                            #      or choose one of your own liking.
                                            #      2) node, npm,... are best NOT installed/run as ROOT.
                                            #         (see here: https://github.com/isaacs/npm/blob/master/README.md)

NAME=node                                   # name of the node.js executable
DAEMON=/usr/local/bin/$NAME                 # this SHOULD POINT TO where your node executable is
#
#                                                                              #
#                   END </MODIFY TO REFLECT YOUR SETTINGS>                     #
#                (Nothing else to modify from this point on...)                #
# ------------------------------------------------------------------------------ 





# Do NOT "set -e"

[ $UID -eq "0" ] && LOCAL_VAR_RUN=/var/run # in case this script is run by root, override user setting
THIS_ARG=$0
INIT_SCRIPT_NAME=`basename $THIS_ARG`
[ -h $THIS_ARG ] && INIT_SCRIPT_NAME=`basename $(readlink $THIS_ARG)` # in case of symlink
INIT_SCRIPT_NAME_NOEXT=${INIT_SCRIPT_NAME%.*}                            
PIDFILE="$LOCAL_VAR_RUN/$INIT_SCRIPT_NAME_NOEXT.pid"
SCRIPTNAME=/etc/init.d/$INIT_SCRIPT_NAME

# Exit if the package is not installed
[ -x "$DAEMON" ] ||  { echo "can't find Node.js ($DAEMON)"  >&2; exit 0; }

# Exit if the 'run' folder is not present
[ -d "$LOCAL_VAR_RUN" ] || { echo "Directory $LOCAL_VAR_RUN does not exist. Modify the '$INIT_SCRIPT_NAME_NOEXT' init.d script ($THIS_ARG) accordingly" >&2; exit 0; }

# Read configuration variable file if it is present
[ -r /etc/default/$INIT_SCRIPT_NAME ] && . /etc/default/$INIT_SCRIPT_NAME

# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh

# Define LSB log_* functions.
# Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
. /lib/lsb/init-functions

# uncomment to override system setting
# VERBOSE=yes

#
# Function that starts the daemon/service
#
do_start()
{
    # Return
    #   0 if daemon has been started
    #   1 if daemon was already running
    #   2 if daemon could not be started
    start-stop-daemon --start --quiet --pidfile $PIDFILE --chuid $NODEUSER --background --exec $DAEMON --test > /dev/null \
        || { [ "$VERBOSE" != no ] && log_daemon_msg  "  --->  Daemon already running $DESC" "$INIT_SCRIPT_NAME_NOEXT"; return 1; }
    start-stop-daemon --start --quiet --chuid $NODEUSER --make-pidfile --pidfile $PIDFILE --background --exec $DAEMON -- \
        $DAEMON_ARGS \
        || { [ "$VERBOSE" != no ] && log_daemon_msg  "  --->  could not be start $DESC" "$INIT_SCRIPT_NAME_NOEXT"; return 2; }
    # Add code here, if necessary, that waits for the process to be ready
    # to handle requests from services started subsequently which depend
    # on this one.  As a last resort, sleep for some time.
    [ "$VERBOSE" != no ] && log_daemon_msg  "  --->  started $DESC" "$INIT_SCRIPT_NAME_NOEXT"
}

#
# Function that stops the daemon/service
#
do_stop()
{
    # Return
    #   0 if daemon has been stopped
    #   1 if daemon was already stopped
    #   2 if daemon could not be stopped
    #   other if a failure occurred
    start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 --pidfile $PIDFILE  --chuid $NODEUSER --name $DAEMON
    RETVAL="$?"
    #[ "$VERBOSE" != no ] && [ "$RETVAL" = 1 ] && log_daemon_msg  "  --->  SIGKILL failed => hardkill $DESC" "$INIT_SCRIPT_NAME_NOEXT"
    [ "$RETVAL" = 2 ] && return 2
    # Wait for children to finish too if this is a daemon that forks
    # and if the daemon is only ever run from this initscript.
    # If the above conditions are not satisfied then add some other code
    # that waits for the process to drop all resources that could be
    # needed by services started subsequently.  A last resort is to
    # sleep for some time.
    start-stop-daemon --stop --quiet --oknodo --retry=0/3/KILL/5 --pidfile $PIDFILE  --chuid $NODEUSER --exec $DAEMON -- $DAEMON_ARGS
    [ "$?" = 2 ] && return 2
    # Many daemons don't delete their pidfiles when they exit.
    rm -f $PIDFILE
  [ "$VERBOSE" != no ] && [ "$RETVAL" = 1 ] && log_daemon_msg "  --->  $DESC not running" "$INIT_SCRIPT_NAME_NOEXT"
  [ "$VERBOSE" != no -a "$RETVAL" = 0 ] && log_daemon_msg "  --->  $DESC stopped" "$INIT_SCRIPT_NAME_NOEXT"
    return "$RETVAL"
}

#
# Function that sends a SIGHUP to the daemon/service
#
do_reload() {
    #
    # If the daemon can reload its configuration without
    # restarting (for example, when it is sent a SIGHUP),
    # then implement that here.
    #
    start-stop-daemon --stop --quiet --signal 1 --pidfile $PIDFILE  --chuid $NODEUSER --name $NAME
    return 0
}

#
# Function that returns the daemon 
#
do_status() {
  #
  # http://refspecs.freestandards.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
  # 0 program is running or service is OK
  # 1 program is dead and /var/run pid file exists
  # (2 program is dead and /var/lock lock file exists) (not used here)
  # 3 program is not running
  # 4 program or service status is unknown
  RUNNING=$(running)

  # $PIDFILE corresponds to a live $NAME process
  ispidactive=$(pidof $NAME | grep `cat $PIDFILE 2>&1` >/dev/null 2>&1)
  ISPIDACTIVE=$?

  if [ -n "$RUNNING" ]; then
    if [ $ISPIDACTIVE ]; then 
      log_success_msg "$INIT_SCRIPT_NAME_NOEXT (launched by $USER) (--chuid $NODEUSER) is running"
      exit 0      
    fi
  else
    if [ -f $PIDFILE ]; then
      log_success_msg "$INIT_SCRIPT_NAME_NOEXT (launched by $USER) (--chuid $NODEUSER) is not running, phantom pidfile $PIDFILE"
      exit 1
    else
      log_success_msg "no instance launched by $USER, of $INIT_SCRIPT_NAME_NOEXT (--chuid $NODEUSER) found"
      exit 3
    fi
  fi

}

running() {
  RUNSTAT=$(start-stop-daemon --start --quiet --pidfile $PIDFILE --chuid $NODEUSER --background --exec $DAEMON --test > /dev/null)
  if [ "$?" = 1 ]; then
    echo y
  fi

}


case "$1" in
  start)
    [ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$INIT_SCRIPT_NAME_NOEXT"
    do_start
    case "$?" in
        0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
        2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
    esac
    ;;
  stop)
    [ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$INIT_SCRIPT_NAME_NOEXT"
    do_stop
    case "$?" in
        0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
        2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
    esac
    ;;
  #reload|force-reload)
    #
    # If do_reload() is not implemented then leave this commented out
    # and leave 'force-reload' as an alias for 'restart'.
    #
    #log_daemon_msg "Reloading $DESC" "$NAME"
    #do_reload
    #log_end_msg $?
    #;;
  restart|force-reload)
    #
    # If the "reload" option is implemented then remove the
    # 'force-reload' alias
    #
    log_daemon_msg "Restarting $DESC" "$INIT_SCRIPT_NAME_NOEXT"
    do_stop
    case "$?" in
      0|1)
        do_start
        case "$?" in
            0) log_end_msg 0 ;;
            1) log_end_msg 1 ;; # Old process is still running
            *) log_end_msg 1 ;; # Failed to start
        esac
        ;;
      *)
        # Failed to stop
        log_end_msg 1
        ;;
    esac
    ;;
  status)
    do_status
  ;;
  *)
    #echo "Usage: $SCRIPTNAME {start|stop|restart|reload|force-reload}" >&2
    echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload}" >&2
    exit 3
    ;;
esac

exit 0
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