Pass all stdout line by line to an file, reopening it periodically.
Provides an easy way to rotate log files for applications which are not clever enough to reopen logfiles for themselves.
Reopener was obsolete since Release 5.0 OldPew (16 Feb 2016), when we completely switched to systemd with journald as logging facility.
But first decade of March 2016 shows the Journald isn't the best solution for reliable logging. For example, it can die when memory of the node is consumed by another daemon and experience shows it doesn't recover after such issue.
So we decided to switch our daemons back to the simple pipe writer with old good logrotate tool.
/usr/bin/stupid-daemon | reopener /var/log/stupid-daemon.log