DansGuardian is a WebProxy with phrase based filtering, useful for schools or other institutions which can't afford to have children viewing pornography. It is GPLed, but uses a weird scheme placing restrictions on the permission to download it for commercial users.
cat > /etc/logrotate.d/dansguardian << EOF /var/log/dansguardian/access.log {
rotate 31 daily prerotate
/etc/init.d/dansguardian stop || true
endscript postrotate
sleep 2 && /etc/init.d/dansguardian start || \ (sleep 2; /etc/init.d/dansguardian start)
endscript
} EOF
This just adds in a sleep and a second attempt to restart DansGuardian if the first fails (the || will execute only if the output from the init script is a fail code).
4 pages link to DansGuardian: