While I disagree with Mark about usefulness of exit status (at least
of exit status 0 in this case), in case of packages, it's pretty easy
to check some vital file for existence as I stated already. I use such
a method to detect availability of a package, and it never harmed me.
Moreover, I use it like follows:
classes:
"ntpd_installed" expression => fileexists("/usr/sbin/ntpd");
packages
!ntpd_installed::
"ntpd"
package_method => yum,
package_policy => "add";
This approach saves me from wasting CPU and time for unnecessary
package manager invocation when a package is already installed.
2010/9/17 Mark Burgess <mark.burg...@iu.hio.no>:
>
>
> On 09/17/2010 11:09 AM, Davide Brini wrote:
>> On Friday 17 Sep 2010 09:59:10 Seva Gluschenko wrote:
>>
>>> Davide,
>>>
>>> as far as I'm known, Cfengine does not analyze package manager exit
>>> status. You might check certain file from a package for existence or
>>> ask Mark to add exit status recognition :)
>>
>> Well that makes it pretty useless doesn't it? How can one detect if the
>> installation failed (or succeeded, for that matter)? Even the documentation
>> itself uses that same exact code (classes => if_ok ...) to make an example of
>> setting a class upon success.
>>
>> The documentation says "Package promises are like commands promises in the
>> sense that cfengine promises nothing about the outcome of executing a
>> command.
>> All it can promise is to interface with it, starting it and using the results
>> in good faith. Packages are basically `outsourced', to invoke IT parlance."
>>
>> As I read it, "using the result in good faith" should mean "trust the
>> command", including its exit status, which is also (imho) the only possible
>> sensible policy, short of building package management into cfengine.
>>
>
> David, the problem is one of semantics. In bulk operations, some things
> succeed and some
> fail. You are entirely slave to the behaviour of the package manager, making
> it difficult
> to have a consistent behaviour that everyone can agree on. Installing one by
> one is
> inefficient, but possible.
>
> Try to think more about the final (desired) state rather than the outcome of
> the shell
> command.
>
> M
>
--
SY, Seva Gluschenko.
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