#!/bin/bash

# This script launches a videotext-process to display a videotext-file.
# If videotext is already running, it justs sends a signal to the old
# process to make it display the new file.

PIDFILE=~/.view_vtx.pid
trap "" USR1

if [ $# -ne 1 ]; then
  echo "Usage: view_vtx <file>" >&2
  exit 1
fi

if [ -e "$PIDFILE" ]; then
  pid="`cat $PIDFILE`"
  cat "$1" > /tmp/vtx$pid
  kill -USR1 $pid &>/dev/null && exit
fi

# This part gets executed only when no pid-file exists in the user's home-
# directory or we weren't able to send a signal to the old videotext-process,
# which probably means that the contents of the pid-file are obsolete.

trap "rm -f $PIDFILE" 0
pid=$$
echo $pid > "$PIDFILE"
cat "$1" > /tmp/vtx$pid
videotext -f "/tmp/vtx$pid" &
vtxpid=$!
trap "kill -USR1 $vtxpid" USR1
wait >/dev/null
rm -f /tmp/vtx$pid