s6
Software
skarnet.org
 The s6-ftrig-wait program 
s6-ftrig-wait subscribes to a fifodir and
waits for a pattern of events to occur on this fifodir.
 Interface 
     s6-ftrig-wait [ -t timeout ] fifodir regexp
 -  s6-ftrig-wait subscribes to fifodir 
-  It waits for the series of events received on fifodir
to match regexp. regexp must be an
Extended
Regular Expression. 
-  When the series of read events matches regexp,
s6-ftrig-wait prints the last event it received to stdout (one byte followed by a newline),
then exits 0. 
 Options 
 -  -t timeout : if the events on fifodir have not
matched regexp after timeout milliseconds, print an error message on
stderr and exit 1. By default, s6-ftrig-wait waits indefinitely for a matching series
of events.