[Clarification] pid:! vs pid:

[hongkongkiwi]

I notice that there are some places in the documentation where the syntax is: pid:!/var/run/myapp.pid

and in another place it shows: pid:/var/run/myapp.pid

What is the exclamation mark for? is this necessary?

[hongkongkiwi]

Oh I see, it's a little bit confusing in the docs, but from my understanding: pid: then finit creates and manages the pid pid:! then finit monitors the pid (but does not create or manage)

[troglobit]

Yup, it's very confusing, but you got it. By default the PID file name for a monitored service is discovered by an inotify callback that reads the contents of PID files from /run and matches them with services. The special case for pid:! is to cover directories that Finit does not monitor. (There is also a historical/legacy reason for it ...)

[hongkongkiwi]

Subsequently I found this in pid.c which was helpful. Just a suggestion that maybe this can be in the docs:

/*
 * This function parses a PID file @arg for @svc.
 *
 * The logic is explained below.  Please note that using the first form
 * of the syntax not only creates and removes the PID file, but it also
 * calls touch to update the mtime on service_restart(), only applicable
 * to processes that accept SIGHUP.  This to ensure dependent services
 * are sent SIGCONT properly on reload, otherwise their condition would
 * never be asserted again after `initctl reload`.
 *
 * pid          --> /run/$(basename).pid
 * pid:foo      --> /run/foo.pid
 * pid:foo.pid  --> /run/foo.pid
 * pid:foo.tla  --> /run/foo.tla.pid
 * pid:/tmp/foo --> /tmp/foo.pid        (Not handled by pidfile plugin!)
 *
 * An exclamation mark, or logial NOT, in the first character position
 * indicates that Finit should *not* manage the PID file, and that the
 * process uses a "non-standard" location.  Eg. if service is 'bar'
 * Finit would assume the PID file is /run/bar.pid and the below simply
 * 'redirects' Finit to use the correct PID file.
 *
 * pid:!foo          --> !/run/foo.pid
 * pid:!/run/foo.pid --> !/run/foo.pid
 *
 * Note, nothing is created or removed by Finit in this latter form.
 */

[troglobit]

The project is open to receive patches and pull requests to improve the documentation.