On Sun, Apr 12, 2009 at 14:14, Michael Alipio <[email protected]> wrote:
>
> Hi,
>
> I have a program that constantly displays values on the screen. The program
> 'ping' for example.
>
> What I'd like to do is watch the output and as soon as i see some values, i
> would do something. For example, as suppose when pinging a host I would
> constantly get a reply. however, if I remove the network cable, of my pc, I
> would start seeing host unreachable or something. As soon as I see this
> message, I would like to do something. This is how I want to do this
> (executing the program once and watching the output). I could probably run
> ping every one second and check the output of each execution, however, that
> is not how I want to do it. The program I will be running has to be run only
> once, like for example the 'top' program.
>
> Any idea how to accomplish this?
snip
Programs like ping that output a stream of information are easy to work with:
ping wonkden.net | perl -ne 'print "I saw $_"'
Perl defaults to a line buffered mode, so if your the program you want
to watch outputs lines, then you just need a loop watching stdin (as
above). To use top, you must put it in logging mode
OS X
top -l 0 | perl -ne 'print if /firefox/'
Linux
top -b | perl -ne 'print if /firefox/'
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
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