If one of the points of switching to a new init system in Debian is
to get rid of huge
init.d scripts, I doubt we need to switch away from sysvinit and
init.d scripts at all. Here is an example init.d script, ie a rewrite
of /etc/init.d/rsyslog:
#!/lib/init/init-d-script
### BEGIN INIT INFO
# Provides: rsyslog
# Required-Start: $remote_fs $time
# Required-Stop: umountnfs $time
# X-Stop-After: sendsigs
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: enhanced syslogd
# Description: Rsyslog is an enhanced multi-threaded syslogd.
# It is quite compatible to stock sysklogd and can be
# used as a drop-in replacement.
### END INIT INFO
DESC="enhanced syslogd"
DAEMON=/usr/sbin/rsyslogd
Pretty minimalistic to me... For the record, the original sysv-rc
script was 137 lines, and the above is just 15 lines, most of it meta
info/comments.
How to do this, you ask? Well, one create a new script
/lib/init/init-d-script looking something like this:
#!/bin/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
}
SCRIPTNAME=$1
scriptbasename="$(basename $1)"
echo "SN: $scriptbasename"
if [ "$scriptbasename" != "init-d-library" ] ; then
script="$1"
shift
. $script
else
exit 0
fi
NAME=$(basename $DAEMON)
PIDFILE=/var/run/$NAME.pid
# 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
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|status|restart|force-reload}" >&2
exit 3
;;
esac
:
It is based on /etc/init.d/skeleton, and could be improved quite a
lot. I did not really polish the approach, so it might not always
work out of the box, but you get the idea. I did not try very hard to
optimize it nor make it more robust either.
A better argument for switching init system in Debian than reducing
the size of init scripts (which is a good thing to do anyway), is to
get boot system that is able to handle the kernel events sensibly and
robustly, and do not depend on the boot to run sequentially. The boot
and the kernel have not behaved sequentially in years.
