The s6-ftrig-listen program
s6-ftrig-listen subscribes to several fifodirs, then spawns a program, then waits for pattern of events to occur on the fifodirs.
Interface
In an execlineb script:
s6-ftrig-listen [ -a | -o ] [ -t timeout ] { fifodir1 regexp1 fifodir2 regexp2 ... } prog...
- s6-ftrig-listen subscribes to fifodir1 with the regexp regexp1, to fifodir2 with the regexp regexp2, and so on.
- It then forks and exec prog... with all its arguments
- It waits for the series of events received on fifodir-i to match regexp-i, The regexp-i must be Extended Regular Expressions.
- When the series of read events matches the regexps, s6-ftrig-listen exits 0.
Options
- -t timeout : if the events on the fifodirs have not matched the regexps after timeout milliseconds, print an error message on stderr and exit 1. By default, s6-ftrig-listen waits indefinitely for a matching series of events.
- -a : and (conjunction). s6-ftrig-listen will only exit when all the fifodir-i have been notified with events matching the corresponding regexp-i. This is the default.
- -o : one (disjunction). s6-ftrig-listen will exit as soon as one of the fifodir-i has been notified with events matching its regexp-i.
Notes
s6-ftrig-listen can be used outside of an execlineb script by using the internal argv syntax, but this syntax is an implementation detail and is not documented as stable. In a shell script, use execlineb -Pc 's6-ftrig-listen ...' to get the benefits of the execlineb brace syntax.