This will be used in wordpress logfollower version.

This is for concistency purpose.

This allow submanager to do some cleanup when it receive sigterm
(in this case removing pid file and killing subprocess).

This script allow to run a command and restart it
it if some files changes.

The submanager catch SIGUSR1 and checks if the specified
files has changed.

It can use a pid file where its own pid is written.

This is usefull for restarting a service from a recipe.

Example :
  submanager -c config.cfg -- command --with-options -y
    Run “command --with-options -y” and restart it if
    config.cfg is modified after receiving SIGUSR