trap stdout and stderr and format without adding to command line?

trap stdout and stderr and format without adding to command line?

[Trevor Wennblom]

Hello,

I'm attempting to find a way to arbitrarily format stdout and stderr by default.

Essentially:

% ls
  [stdout]  file00  file03  file06  file09  file12  file15  file18
  [stdout]  file01  file04  file07  file10  file13  file16  file19
  [stdout]  file02  file05  file08  file11  file14  file17
%

The closest I've gotten is Jeroen van Wolffelaar's annotate script[1] and trying to wrap it with preexec (where much learning occurred and adventure was had).

I'm guessing I could compile a custom shell to always prefix the command with the annotate script. Alternately could stdout/stderr be modified by the shell itself?

Second question, somewhat related. I noticed the annotate script would treat output differently. For instance; stripping coloring, treating 'ls -C' like 'ls -1', etc.

trevor

[1]: http://jeroen.a-eskwadraat.nl/sw/annotate/annotate

Re: trap stdout and stderr and format without adding to command line?

[Bart Schaefer]

On Jun 28,  9:42pm, Trevor Wennblom wrote:
} 
} I'm attempting to find a way to arbitrarily format stdout and stderr
} by default.

I suggest you read the thread around these posts:

http://www.zsh.org/mla/users/2011/msg00358.html
http://www.zsh.org/mla/users/2011/msg00361.html

Although not exactly the same question, it will give you some idea of
the complications you're up against.  

} I'm guessing I could compile a custom shell to always prefix the
} command with the annotate script.

If you're only worried about doing this from interactive shells, some
zle widget programming (override accept-line, for example) may suffice.

} Alternately could stdout/stderr be modified by the shell itself? 

Generally speaking, no, or at least not without potentially changing
the behavior of the commands (see your next question).  You'd want to
exclude programs such as editors that expect to interact, etc.

} Second question, somewhat related. I noticed the annotate script would
} treat output differently.  For instance; stripping coloring, treating
} 'ls -C' like 'ls -1', etc.

It doesn't "strip" anything -- the commands themselves are noticing that
the output is not a terminal, and altering their behavior accordingly.

If you want to do this transparently, you need to at least be using the
zsh/zpty module -- see Functions/Misc/nslookup, for example.  E.g. if
you want to prefix every line with "  [stdout]  " you could create a
zpty terminal that is 12 columns narrower than your actual terminal,
so that the output would leave enough space.