CEHJ
asked on
Cups and /dev/lp0
Goal: to ensure that a print command issued by ImageMagick 'display' (which apparently wants to print to /dev/lp0) is forwarded to the Cups server
Firstly, i don't know if this is necessary (i probably don't know enough about Cups) but i have the following script:
This works ok, but i thought it should properly become an init.d script so i edited /etc/init.d/skeleton to provide:
Starting went off ok, but (possibly because of the infinite loop [i don't know]) no pid file ever got created so stopping the 'service' simply failed.
So the question is
a. is my workaround even necessary?
b. if yes, how can i ensure proper working of the script as far as changing state is concerned (between running, stopped, status etc)
Firstly, i don't know if this is necessary (i probably don't know enough about Cups) but i have the following script:
#!/bin/bash
spooling_file=/tmp/img.ps
printer_dev=/dev/lp0
if [ ! -p ${printer_dev} ];then
sudo mkfifo ${printer_dev}
fi
while [ true ]; do
cat ${printer_dev} >${spooling_file}
lp ${spooling_file}
done
This works ok, but i thought it should properly become an init.d script so i edited /etc/init.d/skeleton to provide:
#! /bin/sh
### BEGIN INIT INFO
# Provides: skeleton
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Example initscript
# Description: This file should be used to construct scripts to be
# placed in /etc/init.d.
### END INIT INFO
# Author: Foo Bar <foobar@baz.org>
#
# Please remove the "Author" lines above and replace them
# with your own name if you copy and modify this script.
# Do NOT "set -e"
# PATH should only include /usr/* if it runs after the mountnfs.sh script
PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="Use /dev/lp0 with Cups"
NAME=img-backend
DAEMON=/usr/local/bin/$NAME
DAEMON_ARGS="--options args"
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 --background --pidfile $PIDFILE --exec $DAEMON --test > /dev/null \ || return 1
start-stop-daemon --start --quiet --background --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
:
Incidentally do_start was originallydo_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.
}
but i deleted the --test business, firstly because i didn't know what was going on and secondly because with it in, it simply caused two processes to get run.Starting went off ok, but (possibly because of the infinite loop [i don't know]) no pid file ever got created so stopping the 'service' simply failed.
So the question is
a. is my workaround even necessary?
b. if yes, how can i ensure proper working of the script as far as changing state is concerned (between running, stopped, status etc)
SOLUTION
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yes but separating jobs that come through a pipe is a pain to do.
So in stead of using display to print an image use the other ImageMagick command convert to transpose it to PS and feed that to the cups queue... A lot less hassle.
And if you have to process a lot of file you could make a directory,
run incron on it and every time you drop a file into that directory the incron job can process the file.
So in stead of using display to print an image use the other ImageMagick command convert to transpose it to PS and feed that to the cups queue... A lot less hassle.
And if you have to process a lot of file you could make a directory,
run incron on it and every time you drop a file into that directory the incron job can process the file.
ASKER CERTIFIED SOLUTION
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ASKER
Actually i think the pid file issue is simply solved by specifying --make-pidfile to start-stop-daemon. I assumed (incorrectly) that start-stop-daemon created this
ASKER
Thanks. Issue solved by --make-pidfile
ASKER