Unix Articles & FAQ

Squid has a restart feature built in. This greatly simplifies starting Squid and means that you don't need to use RunCache or inittab. At the minimum, you only need to enter the pathname to the Squid executable. For example:

/usr/local/squid/sbin/squid

Squid will automatically background itself and then spawn a child process. In your syslog messages file, you should see something like this:

Sep 23 23:55:58 kitty squid[14616]: Squid Parent: child process 14617 started

That means that process ID 14563 is the parent process which monitors the child process (pid 14617). The child process is the one that does all of the work. The parent process just waits for the child process to exit. If the child process exits unexpectedly, the parent will automatically start another child process. In that case, syslog shows:

Sep 23 23:56:02 kitty squid[14616]: Squid Parent: child process 14617 exited with status 1
Sep 23 23:56:05 kitty squid[14616]: Squid Parent: child process 14619 started

If there is some problem, and Squid can not start, the parent process will give up after a while. Your syslog will show:

Sep 23 23:56:12 kitty squid[14616]: Exiting due to repeated, frequent failures

When this happens you should check your syslog messages and cache.log file for error messages.

When you look at a process (ps command) listing, you'll see two squid processes:

24353  ??  Ss     0:00.00 /usr/local/squid/bin/squid
24354  ??  R      0:03.39 (squid) (squid)

The first is the parent process, and the child process is the one called "(squid)". Note that if you accidentally kill the parent process, the child process will not notice.

If you want to run Squid from your termainal and prevent it from backgrounding and spawning a child process, use the -N command line option.

/usr/local/squid/bin/squid -N

from inittab

On systems which have an /etc/inittab file (Digital Unix, Solaris, IRIX, HP-UX, Linux), you can add a line like this:

sq:3:respawn:/usr/local/squid/sbin/squid.sh < /dev/null >> /tmp/squid.log 2>&1

We recommend using a squid.sh shell script, but you could instead call Squid directly with the -N option and other options you may require. A samplesquid.sh script is shown below:

C=/usr/local/squid
PATH=/usr/bin:$C/bin
TZ=PST8PDT
export PATH TZ

# User to notify on restarts
notify="root"

# Squid command line options
opts=""

cd $C
umask 022
sleep 10
while [ -f /var/run/nosquid ]; do
        sleep 1
done
/usr/bin/tail -20 $C/logs/cache.log 
        | Mail -s "Squid restart on ´hostname´ at ´date´" $notify
exec bin/squid -N $opts

from rc.local

On BSD-ish systems, you will need to start Squid from the "rc" files, usually /etc/rc.local. For example:

if [ -f /usr/local/squid/sbin/squid ]; then
        echo -n ' Squid'
        /usr/local/squid/sbin/squid
fi

from init.d

Squid ships with a init.d type startup script in contrib/squid.rc which works on most init.d type systems. Or you can write your own using any normal init.d script found in your system as template and add the start/stop fragments shown below.

Start:

/usr/local/squid/sbin/squid

Stop:

/usr/local/squid/sbin/squid -k shutdown
n=120
while /usr/local/squid/sbin/squid -k check && [ $n -gt 120 ]; do
    sleep 1
    echo -n .
    n=´expr $n - 1´
done

with daemontools

Create squid service directory, and the log directory (if it does not exist yet).

mkdir -p /usr/local/squid/supervise/log /var/log/squid
chown squid /var/log/squid

Then, change to the service directory,

cd /usr/local/squid/supervise

and create 2 executable scripts: run

rm -f /var/run/squid/squid.pid
exec /usr/local/squid/sbin/squid -N 2>&1

and log/run.

exec /usr/local/bin/multilog t /var/log/squid

Finally, start the squid service by linking it into svscan monitored area.

cd /service
ln -s /usr/local/squid/supervise squid

Squid should start within 5 seconds.