1

My goal

To run x.flux with parameters on startup

My attempt

An init.d script. It can be invoked manually via

sudo /etc/init.d/xflux start
[ ok ] Starting xflux (via systemctl): xflux.service.

My problem

The program "x.flux" is not running properly after startup, i.e. the screen does not get redder as intended. Invoking it manually after startup in the cli with the same arguments works as intended.

The logs and an assumption

I receive

sudo service xflux status
● xflux.service - LSB: xflux start script
   Loaded: loaded (/etc/init.d/xflux; generated; vendor preset: enabled)
   Active: inactive (dead) since [...] CEST; 18min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 4153 ExecStop=/etc/init.d/xflux stop (code=exited, status=0/SUCCESS)
  Process: 4065 ExecStart=/etc/init.d/xflux start (code=exited, status=0/SUCCESS)

systemd[1]: Starting LSB: xflux start script...
xflux[4065]: Couldn't open display (null)
xflux[4065]: .
xflux[4065]: [10B blob data]
xflux[4065]: --------
xflux[4065]: Welcome to xflux (f.lux for X)
xflux[4065]: This will only work if you're running X on console.
systemd[1]: Started LSB: xflux start script.
systemd[1]: Stopping LSB: xflux start script...
systemd[1]: Stopped LSB: xflux start script.

So that might be could-not-open-display-null-error-how-can-i-fix-this but I don't understand how to fix this, if it actually is the problem.

The script

For sake of completion here goes the script

#! /bin/sh
### BEGIN INIT INFO
# Provides:          xflux
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: xflux start script
### END INIT INFO

# Do NOT "set -e"

# PATH should only include /usr/* if it runs after the mountnfs.sh script
PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="Description of the service"
NAME=xflux
RUNDIR=/usr/local/bin/$NAME
DAEMON=/usr/local/bin/$NAME
DAEMON_ARGS="hereGoesMyLocationAsParam"
PIDFILE=/var/run/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME

# Exit if the package is not installed
[ -x "$DAEMON" ] || exit 0

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

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

# Define LSB log_* functions.
# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
# and status_of_proc is working.
. /lib/lsb/init-functions

#
# 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) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
    esac
    ;;
  status)
    status_of_proc "$DAEMON" "$NAME" && exit 0 || exit $?
    ;;
  #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|reload|force-reload}" >&2
    echo "Usage: $SCRIPTNAME {start|stop|status|restart|force-reload}" >&2
    exit 3
    ;;
esac

:
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3
  • The reason I've seen the most for this is that your script depends on some environment variable (PATH being the most commonly seen with this) that has different values when run manually from on startup. (I'm off to bed, so I don't have time to read through your script to see if there's another obvious reason or another environment variable that is depended on.) Commented Aug 30, 2019 at 22:23
  • As you can see in [ ok ] Starting xflux (via systemctl): xflux.service. your distribution uses systemd. Hence, liking it or not, you may have a simpler life by learning how to use systemd feature and write a service unit file to run your program, instead of sticking to /etc/init.d/. That should remove the need of a lot of boilerplate in your current code. Commented Aug 30, 2019 at 22:30
  • 1
    Couldn't open display (null) typically means that the variable DISPLAY is not set, hence the application that tries to run does not know so to speak where to display itself (a computer can have multiple local or remote display devices). Also is your program, which seems graphical, expected to run without any user logged in or session? When the computer boots it may not have a graphical interface, so what is your program supposed to do then? If it is tied to a user logged in, you may want instead to start it in some .xsession script or equivalent. There is also systemctl --user. Commented Aug 30, 2019 at 22:32

1 Answer 1

Reset to default
0

So, kudos go to Patrick Mevzek. The hint to look into .xsession brought me to someone with the same need. And from there to Debian's description on xinitrc. The description there states:

Note : Modern Desktop environment also have (easier|GUI) session management tools. (Under Gnome System Menu > Preferences > session). Except for very specific purpose, it shouldn't be necessary to touch xinitrc file.

I use Xfce and yes it has a possibility to add programs on session start under:
-> Settings
-> Session and startup behavior
-> Automatically started programs

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