The s6lockd program
s6lockd is the s6lock daemon. It is a program that manages
a set of lock files in a given directory, and associated timeouts.
s6lockd does not fork, does not background itself automatically,
and does not use syslog. It is not meant to be run directly by the
user: it will be spawned by the
s6lock client library.
There are 2 ways to use s6lockd:
- Use the s6lock_startf() library call.
An s6lockd child will then be spawned from your
calling process, and automatically reaped when you call
s6lock_end(). It requires care with applications that
trap SIGCHLD. It also requires care with lock file permissions:
an s6lockd instance might not be able
to open a lock file created by a former instance run by another
client with different permissions.
- Use the s6lock_start() library call, together with a
For once, this is the recommended setup: s6lockd creates empty
lock files, and having all s6lockd instances run under the same user
simplifies permissions management considerably.
When run as a service, s6lockd has no "standalone" mode: it is
designed to work with a Unix
domain super-server, like
s6lockd follows the UCSPI
interface, it can be directly executed from the super-server.
- Unix does not natively provide a way to stop blocking on a lock
acquisition after a timeout. To emulate such behaviour, s6lockd actually
spawns an s6lockd-helper child per