daemontools is a collection of tools for managing UNIX services.

supervise monitors a service. It starts the service and restarts
the service if it dies. Setting up a new service is easy: all
supervise needs is a directory with a run script that runs the
service.

multilog saves error messages to one or more logs. It optionally
timestamps each line and, for each log, includes or excludes lines
matching specified patterns. It automatically rotates logs to limit
the amount of disk space used. If the disk fills up, it pauses and
tries again, without losing any data.