From 496b7282f2b8fb56cc88d7113202ef0e1d9ce22c Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Mon, 9 Mar 2015 17:21:12 +0000 Subject: - Added s6-uevent-listener and s6-uevent-spawner - s6-devd is now a wrapper around the former two - version: bump to 2.0.2.0, still missing s6-devd doc --- doc/s6-uevent-spawner.html | 79 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 doc/s6-uevent-spawner.html (limited to 'doc/s6-uevent-spawner.html') diff --git a/doc/s6-uevent-spawner.html b/doc/s6-uevent-spawner.html new file mode 100644 index 0000000..e9be726 --- /dev/null +++ b/doc/s6-uevent-spawner.html @@ -0,0 +1,79 @@ + + + + + s6-linux-utils: the s6-uevent-spawner program + + + + + + +

+s6-linux-utils
+Software
+skarnet.org +

+ +

The `s6-uevent-spawner` program

+ +

+s6-uevent-spawner listens to its standard input for +netlink-style events, and launches a helper program for every event, +similarly to what the hotplug interface does. +

+ +

+ It is meant to be used together with +s6-uevent-listener. +

+ +

Interface

+ +

+     s6-uevent-spawner [ -v verbosity ] [ -l linevar ] [ -t l:t:k ] prog...
+

+ +

s6-uevent-spawner listens to its stdin for a series of strings +representing kernel uevents, as formatted by +s6-uevent-listener.
For every event it reads, it spawns prog... with +the event variables added to the environment, just as if prog... +had been registered in /proc/sys/kernel/hotplug. However, +it reads the events sequentially, and waits for a prog instance +to finish before spawning another one.
When s6-uevent-spawner receives EOF: if an instance of +prog is alive, it first waits for it to die. Then it exits +0.

+ +

Options

+ +

-v verbosity : be more or less verbose. +Default verbosity is 1. 0 only prints fatal error messages. 3 is too much.
-l linevar : make the event description +(i.e. the first string in the netlink message announcing the event) +available in prog under the environment variable linevar. +By default, this first string is ignored - it is not needed, all the +event information is already in the other variables.
-t l:t:k : If l, t or k is +specified, they specify timeouts; by default, they are infinite. +If prog... is still alive after l milliseconds, s6-devd sends +it a SIGTERM. Then, if prog... is still alive after t more +milliseconds, s6-devd sends it a SIGKILL. Then, if prog... is still +alive after k more milliseconds, s6-uevent-spawner yells and exits 99.

+ +

Notes

+ +

The prog... helper should be very short-lived, +even if you are not using the -t option to s6-devd. Since helpers are +spawned sequentially, slow helpers can make events queue up and fill up +buffers.

+ + + -- cgit v1.2.3

The s6-uevent-spawner program

Interface

Options

Notes

The `s6-uevent-spawner` program