s6
Software
skarnet.org
 The s6-instance-create program 
s6-instance-create creates a new instance of a currently supervised
instanced service.
 Interface 
     s6-instance-create [ -d | -D ] [ -P ] [ -f ] [ -t timeout ] servicedir name
 -  s6-instance-create expects a running, supervised
instanced service in servicedir.
This service typically has been created by linking the result of an
s6-instance-maker invocation into
an existing scan directory. 
-  s6-instance-create creates a new instance of that service, named
name. Depending on the given options, it may start it
immediately, or keep it down until a later
s6-instance-control invocation. 
-  It waits for the new instance to be ready to take commands from
s6-instance-control. 
-  It exits 0. 
 Exit codes 
 -  0: success 
-  99: timeout while waiting for the instance supervisor to start 
-  100: wrong usage 
-  111: system call failed 
 Options 
 -  -d : down. The instance supervisor will be started, but the instance
itself will remain down. Any down file for the instance will be
deleted. By default, if neither the -d nor -D options have
been given, the supervisor auto-starts the instance as soon as it runs. 
-  -D : down, and stay down. The instance supervisor will be started,
but the instance itself will remain down. A down file
will be created for the instance. By default, if neither the -d nor -D options have
been given, the supervisor auto-starts the instance as soon as it runs. 
-  -P : public. Everyone will be able to subscribe to the
instance supervisor's notification. By default, only processes running with the same gid
as the instanced service can subscribe to it. 
-  -f : force permissions. You should never need to use this
option, it is only there for testing purposes. 
-  -t timeout : if the instance supervisor has not started
after timeout milliseconds, s6-instance-create will print a message
to stderr and exit 99. By default, timeout is 0, which means no time
limit. 
 Notes 
 -  s6-instance-create is similar to
s6-svlink, because it uses the same underlying
library functions. Under the hood, an instance is a regular service running
on a supervision tree that is specific to the instanced service, and
s6-instance-create adds a service directory to that tree and ensures it gets
supervised. 
-  If the template for the service is logged, then s6-instance-create will
wait until supervisors have been spawned for both the instance and its logger. 
-  s6-instance-create and s6-instance-delete
are relatively expensive operations, because they have to recursively copy or
delete directories and use the synchronization mechanism
with the instance supervisor, compared to
s6-instance-control which only has to send
commands to already existing supervisors. If you are going to turn instances on and
off on a regular basis, it is more efficient to keep the instance existing and control
it with s6-instance-control than it is to
repeatedly create and delete it.