Automation: (Was: List of Command Line Tools) - Hijacked from PGP

[Joshua Zeidner]

 Hi Al,

  you might want to take a look at the perl -n -e switches.

  -jmz

On Sun, May 17, 2009 at 10:51 AM, Al Tobey <tobert at gmail.com> wrote:
> On Sun, May 17, 2009 at 6:39 AM, Bryan O'Neal
> <boneal at cornerstonehome.com> wrote:
>> Great list. I would also add scp (secure copy) ps aux (list of currently
>> running processes) and I also like any app that has a command line function,
>> like xmms.
>>
>> While we are on the subject, excluding writing everything in bash, what is
>> the best way for various programs (pick your language) to access command
>> line tools and parse the output?  I would like to crank my automation
>> techniques up a level.
>
> In perl,
>
> use strict;
> use warnings;
>
> # pipe at the end of the open string means run the program and grab its stdout
> # pipe at the beginning means let me print to its stdin
> # see perldoc -f open
> # see perldoc IPC::Open2 for how to do both sides
> open( my $fh, '/usr/bin/foo |' )
>    or die "Could not execute foo: $!";
>
> while ( my $line = <$fh> ) {
>    chomp($line); # kill whatever newline/carriage return may be there
>     # process it ...
> }
>
> close $fh; # optional, but good style
>
> The old standards are still good too, just not as elegant (most of the time).
>
> my @output = `/usr/bin/foo`;
> system( '/usr/bin/foo' );
>
> Also check out http://search.cpan.org/~rcaputo/POE-1.005/lib/POE/Wheel/Run.pm
>
> POE takes a bit to learn, but it's really worth it when you have a
> single process managing hundreds of tasks without threading or fork.
> Python's twisted framework should have something similar and work
> similarly, but would be more likely to appease the language snobs.
>
> -Al
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