The simplest (perl) filter for the job

geohar has asked for the wisdom of the Perl Monks concerning the following question:

Ok, this is a bit of an odd one but it's been bugging me for days. I'm using perl as part of a filter for listing all running applications. The point is to be able to use the list returned as a completion for a command in tcsh... Ok. So this is really fairly obscure.

I'm running OSX, so some explanation of how applications show up in ps listings may be required. Using ps -axwwo command= I'll get a list of processes including those without controlling terminals, and doesn't width-limit the result and only prints the command path + arguments.

As well as the applications which are running, there's also going to be a fair few other processes. I don't want those in the list.

The rules for how an application looks in the ps listing:

1. All applications have XXX.app/Contents/ in their path, the actual executable being at something like somepath/XXX.app/Contents/MacOS/XXX Or perhaps somepath/XXX.app/Contents/MacOSClassic/XXX. Anyhow, all applications have XXX.app/Contents/ in their path.

2. Applications may infact be nested (helper apps etc). So may appear as somepath/XXX.app/Contents/Resources/Helper.app/Contents/MacOS/Helper which kinda confuses things somewhat, as the running app is actually Helper, not XXX.

3. In the ps listing you have often a postfixed "-psn=101010" indicating the psn of the application.

4. Incidentally application names may contain spaces ;(

I want a listing consisting of the running applications, only. In the form

A.app
B.app
C.app
[download]

etc. even when C.app may be inside D.app's bundle folder.

Yeah, this is very esoteric.

So currently, I have the following line which I execute in tcsh.

/bin/ps -axwwo command= | grep '\.ap\{2\}/Contents' | perl -p -e 's|^/(([^/]+)+/)+(.+\.app)/.*$|$3|'

Can anyone do better? I'm looking for a one-liner. I'd love to fold the grep into the perl, but it complicates processes finding themselves, and I couldn't see how to do it as a perl filter...

Note that the use of the grep and it's bizarre construction means it doesn't match itself or the perl filter.

Comment on The simplest (perl) filter for the job Select or Download Code

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Re: The simplest (perl) filter for the job by ccn (Vicar) on Oct 15, 2004 at 09:30 UTC
`/bin/ps -axwwo command= \| perl -pe '$_ = /\.app\/Contents/ && m{([^/]+ +\.app)/} ? $1 : ""'` [download] Update: shorten	[reply] [d/l]
Re^2: The simplest (perl) filter for the job by geohar (Acolyte) on Oct 15, 2004 at 10:03 UTC
Excellent. Though a couple of mods `/bin/ps -axwwo command= \| perl -pe '$_="" if ! /\.app\/Contents/ ; $_ += m{([^/]+\.app)/} ? "$1\n" : ""'` [download] The expression order needs to be swapped as the previous order stripped off the /Contents before it can be matched by the second expression. Also a space after the '!' prevents tcsh trying to history-expand the search... Thanks	[reply] [d/l]
Re^2: The simplest (perl) filter for the job by geohar (Acolyte) on Oct 15, 2004 at 11:07 UTC
Yeah, that's nice. Out of interest, is the match guaranteed to return the last match (as in the case of an app in an app) ? It seems to, but I wasn't sure...	[reply]
Re^3: The simplest (perl) filter for the job by geohar (Acolyte) on Oct 15, 2004 at 11:13 UTC
Damn, replying to my own post. The + or * operator seems to leave the bound backref as the last match out of all the repetitions...	[reply]
Re: The simplest (perl) filter for the job by Roger (Parson) on Oct 15, 2004 at 12:09 UTC
Try to use a regular expression to capture all occurances of .app into an anonymous list, an then retrieve the last occurance of .app in the list: `+(/(\w+.app)/g)[-1]` [download]	[reply] [d/l]