Let me point out that your command is not quite deterministic.
ps -aef | grep blah | head -2 | tail -1 | awk '{print $2}'
Assuming that there is a command named blah that is running, the ps
might return:
UID PID PPID C STIME TTY TIME CMD
99 123 1 0 0:03.56 ?? 0:04.83 blah
99 234 726 0 0:01.99 ?? 0:02.36 bash
99 235 234 0 0:25.36 ?? 0:47.66 awk {print $2}
99 236 235 0 0:04.51 ?? 0:06.78 tail -1
99 237 236 0 0:01.99 ?? 0:02.36 head -2
99 238 237 0 0:25.36 ?? 0:47.66 grep blah
99 239 238 0 0:04.51 ?? 0:06.78 ps -aef
grep selects the lines that match blah
99 123 1 0 0:03.56 ?? 0:04.83 blah
99 238 237 0 0:25.36 ?? 0:47.66 grep blah
head -2 returns the first 2 of these lines (i.e., all of them in this
case)
tail -1 gives the last one:
99 238 237 0 0:25.36 ?? 0:47.66 grep blah
and finally awk '{print $2}' gives
238
BUT, if the blah and grep blah commands had come in the other order in
the list from ps, then you'd get 123. Does that help you?
Here's something to try (particularly if the pattern is fixed):
ps -aef | grep -e '[b]lah' | awk '{print $2}'
(or try it with just the ps|grep part and not the awk)
The thing to note is that '[b]lah' does not match itself because it is
not a 'b' (the only character in the class [b]) followed by 'l', 'a',
and 'h'. It is a 'b' then a ']' and only THEN 'lah'.
Your problem is not capistrano, but the command that it happens to be
running.
(and you could just do it all in one command, too:
run "kill $(ps -aef | grep -e '[b]lah' | awk '{print $2}')"
but then you wouldn't have learned to fish.)
-Rob
On Sep 18, 2009, at 11:46 AM, pete wrote:
>
> I used Capture, which seems a bit cleaner, I don't have the ability to
> use pkill.
>
> However, I get the wrong PID returned??
>
> When I run my command on the command line manually I get 32553, as an
> example.
>
> When Cap runs, it returns 32106, or something like that.
>
> Why am I getting different PIDs?
>
> On Sep 17, 7:45 pm, Donovan Bray <[email protected]> wrote:
>> Use capture instead of run
>> And parameterize the second command to use what was captured
>>
>> Or investigate pskill and killall that can do it in one step
>>
>> On Sep 17, 2009, at 11:28 AM, pete <[email protected]> wrote:
>>
>>> Let me clarify this a little better...
>>
>>> I would like to do something like this:
>>
>>> task :myTask, :roles => :myhost do
>>> run "ps- -aef | grep <searchstring> | head -2 | tail
>>> -1 | awk '{print $2}'"
>>> run "kill <PID FROM PREVIOUS run COMMAND>"
>>> end
>>
>>> On Sep 17, 11:57 am, pete <[email protected]> wrote:
>>>> Hi-
>>
>>>> I want to use Cap to kill a process, but I don't know the PID so
>>>> I am
>>>> using what I have below to get it:
>>
>>>> ps- -aef | grep <searchstring> | head -2 | tail -1 | awk '{print
>>>> $2}'
>>
>>>> Is it possible to use the results of the above command in a custom
>>>> task and kill off the PID that is returned?
>>
>>>> Thanks!
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