Comments for Andrew Birkett's blog

Comment on BBC invents new SI unit by Claire

Claire — Tue, 27 May 2008 08:30:24 +0000

It’s all part of the BBC’s helpful strategy of taking easily understandable news stories and reporting them in such simple terms that they lose all meaning

Comment on Squawk (simple queues using awk) by Andrew

Andrew — Wed, 14 May 2008 11:37:24 +0000

Ken: Yep, that works fine if you are using netcat as a data source and filtering its output with awk. But for squawk I also need the output from awk to be fed back into netcat’s stdin - its a two way conversation. I use netcat -c “my_awk_command” for this. But that means my awk command invocation would need to be escaped otherwise bash will expand things like ‘$0′ which I intend for awk.

Hmm, actually, I think in this case I can surround the awk invocation with single quotes and then consistently use double quotes within the awk script. In an earlier version I was relying on the awk script being bash-expanded to do variable substitution for the queue name. But now I explicitly pass the arguments in with –assign.

Ah, no .. I still need to shell-expand the –assign part of the awk invocation, so it can’t be in single quotes.

This page has some suggestions; I’ll see if I can get it to work: http://www.gnu.org/manual/gawk/html_node/Quoting.html. I didn’t know that if you run something like this:

ls ‘foo’”bar” (no space between the quotes)

.. then ls receives a single argument - I’d always assumed it’d get two arguments.

Comment on Squawk (simple queues using awk) by ken horn

ken horn — Wed, 14 May 2008 10:11:41 +0000

you can get away with this:
#! /bin/bash

(echo “GET / HTTP/1.0″ ; echo “”) | nc http://www.yahoo.com 80 | awk ‘
BEGIN{
i=0
}
{
print i++ “> ” $0;
}’ | head -20

alternatively if you need more processing, use ” instead or you can even process the current file and pipe it to awk if stdin is spare (i’ve used ## comments to give a grep target), using back ticks to get extra nested shells is a neat trick too..

Comment on RAID-1 sans disks by Hugo

Hugo — Thu, 10 Apr 2008 09:16:45 +0000

that’s cool!
very elegant way of working with both bash and lo

Comment on Polymorphic function; a tale of two forM_’s by Porges

Porges — Sun, 06 Apr 2008 10:14:48 +0000

Ah, I had a similar issue earlier. I was looking for forM_ over a Map and found it in the Traversable class… as forM, with no forM_ to be found.

Now I know I should have been looking in Foldable all along…!