Signals are a POSIX inter-process communications mechanism. If you are using Windows then this documentation does not apply.
Zope responds to signals which are sent to the process id specified in the file ‘$INSTANCE_HOME/var/Z2.pid’:
SIGHUP - close open database connections, then restart the server process. A idiom for restarting a Zope server is: kill -HUP `cat $INSTANCE_HOME/var/z2.pid` SIGTERM - close open database connections then shut down. A common idiom for shutting down Zope is: kill -TERM `cat $INSTANCE_HOME/var/Z2.pid` SIGINT - same as SIGTERM SIGUSR2 - close and re-open all Zope log files (z2.log, event log, detailed log.) A common idiom after rotating Zope log files is: kill -USR2 `cat $INSTANCE_HOME/var/z2.pid`