On Fri, 2009-06-12 at 04:46 -0700, Hui wrote:
> Hi guys,
>
> I was enlightened by the 'puppet+augeas modprobe.conf' post (thanks!)
> and was going to put inittab under puppet/augeas management.
>
> My goal is to add this one line for spawning a console on the serial
> port if it doesn't exist:
> co:12345:respawn:/sbin/agetty ttyS0 19200 vt100
>
> However the task proved to be more tricky than I first imaged. There
> were two thing I was stuck on. Firstly inittab tree in augeas starts
> with number instead of arrays, and I had to work around to append with
> ins and last().
Assuming you're happy with appending that line to the end of the file,
you shouldn't need to do anything fancy .. just a bunch of set's should
be fine.
> Secondly the match in onlyif didn't seem to like
> spaces, so I was unsure how I can match the sequence exactly.
That is a bug that's been addressed in the current master branch (ticket
#2141)
> I came up with the following:
> augeas { "inittab":
> context => "/files/etc/inittab",
> changes => [ "set 100/id 'co'",
> "set 100/runlevels 12345",
> "set 100/action respawn",
> "set 100/process \"/sbin/agetty ttyS0 19200 vt100\"",
> ],
> onlyif => "match */id[.='co'] size == 0'",
> #onlyif => "match */process[.='/sbin/agetty ttyS0 19200 vt100']
> size == 0",
> }
>
> So for my first problem, I used an arbitary large number (100) so it's
> outside the existing line ranges - not robust and could inadvertently
> overwrite something else.
A much better way to make sure numbered nodes are truly unique is to use
labels that start with a '0' - you're guaranteed that they will never
appear in a tree that was just read from file; so you'd say "set 01/id
'co'" etc.
> But for the matching, the first onlyif
> works but the commented out one would error with
That can actually be also written as "match *[id='co'] size == 0"
> err: //Augeas[inittab]: Failed to retrieve current state of resource:
> Error sending command 'match' with params ["vt100']", "size", "==",
> "0"]/unknown error - Matching path expression '/files/etc/inittab/*/
> process[.='/sbin/agetty' failed
That's another manifestation of bug #2141.
> I would really want to match on the serial console port (ttyS0) in
> case it's named under a different id on an existing host.
This would really require that Augeas path expressions grow a way to
match regexps or at least substrings, so that you could say
onlyif => "match *[process =~ @^/sbin/agetty tt...@] size == 0"
or some such.
David
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