apache-log-mean-response-time-in-background

#!/bin/sh

logFile=$1
update_time_seconds=1

[ -f "$logFile" ] || { echo "usage: $0 <apache log file>"; exit 1; }

tmp_file=/var/tmp/apache-log-mean-for-snmp--`basename $logFile`
pid_file="$tmp_file.pid"

if [ -f "$pid_file" ]; then
    pid=`cat "$pid_file"`
    rm -f "$pid_file"
    if ps -p "$pid" -o cmd= | grep -q apache-log-mean-response-time; then
	kill $pid
    fi
fi

if [ -f "$tmp_file" ]; then
    # previous background process has given an answer, return it
    cat "$tmp_file"
    rm -f "$tmp_file"
else
    # no value
    echo
fi

# run in background to compute next answer in $tmp_file
nohup apache-log-mean-response-time $update_time_seconds $logFile $tmp_file >/dev/null 2>&1 &
echo $! > "$pid_file"