bash script to restart Apache automatically

I wrote a bash script to restart Apache when it hanged and send email to the admin. The code is shown below. the code will restart Apache if the number of Apache process is zero. The problem is: Apache some time hangs 开发者_Go百科and processes is still not zero,so in this case the script will not restart Apache. The needed is: how do I modify the code to restart Apache if it hanged and the processes is not zero.

#!/bin/bash
if [ `pgrep apache2 -c` -le "0" ]; then
/etc/init.d/apache2 stop
pkill -u www-data  
/etc/init.d/apache2 start
 echo "restarting....."
SUBJECT="Apache auto restart"
# Email To ?
EMAIL="me@mydomain.com"
# Email text/message
EMAILMESSAGE="apache auto restart done"
# send an email using /bin/mail
/bin/mail -s "$SUBJECT" "$EMAIL" "$EMAILMESSAGE"
fi

We used to have Apache segfaulting sometimes on a machine; here's the script we used trying to debug the problem while keeping Apache up. It ran from cron (as root) once every minute or so. It should be self-explanatory.

#!/bin/sh
# Script that checks whether apache is still up, and if not:
# - e-mail the last bit of log files
# - kick some life back into it
# -- Thomas, 20050606

PATH=/bin:/usr/bin
THEDIR=/tmp/apache-watchdog
EMAIL=yourself@example.com
mkdir -p $THEDIR

if ( wget --timeout=30 -q -P $THEDIR http://localhost/robots.txt )
then
    # we are up
    touch ~/.apache-was-up
else
    # down! but if it was down already, don't keep spamming
    if [[ -f ~/.apache-was-up ]]
    then
        # write a nice e-mail
        echo -n "apache crashed at " > $THEDIR/mail
        date >> $THEDIR/mail
        echo >> $THEDIR/mail
        echo "Access log:" >> $THEDIR/mail
        tail -n 30 /var/log/apache2_access/current >> $THEDIR/mail
        echo >> $THEDIR/mail
        echo "Error log:" >> $THEDIR/mail
        tail -n 30 /var/log/apache2_error/current >> $THEDIR/mail
        echo >> $THEDIR/mail
        # kick apache
        echo "Now kicking apache..." >> $THEDIR/mail
        /etc/init.d/apache2 stop >> $THEDIR/mail 2>&1
        killall -9 apache2 >> $THEDIR/mail 2>&1
        /etc/init.d/apache2 start >> $THEDIR/mail 2>&1
        # send the mail
        echo >> $THEDIR/mail
        echo "Good luck troubleshooting!" >> $THEDIR/mail
        mail -s "apache-watchdog: apache crashed" $EMAIL < $THEDIR/mail
        rm ~/.apache-was-up
    fi
fi

rm -rf $THEDIR

We never did figure out the problem...

Can the count of a process really be less than zero?

This should be sufficient:

if ! pgrep apache2 -c >/dev/null; then

You could try to send an http request to apache (e.g. using wget --timeout=10) and if that request times out or fails (exit status != 0), you kill and restart apache.

Why would Apache hang? Can you get to the cause?

There are a number of scripts and tools out there to 'daemonize' apps and watch over them. As you seem to be on Debian or Ubuntu, have a look at the packages daemon and daemontools. I am sure there are others too.