Comments on From the Canyon Edge - :-Dustin Kirkland: Buy 1, get 8 Free! Or, a Useful Awk Hack...

"When systems programming, do you ever find y...

2010-08-27T09:05:27.044-05:00

"When systems programming, do you ever find yourself with an unfamiliar error code, and then you're off Googling what the heck it actually means?"

Never. I read the manuals of the functions I use and account for the errors that might occur. It shouldn't happen that you find yourself with the actual _number_ of the error code. You should rather print a/the message associated with the error as it is handled in your program. Like... right? I mean, am I alone in this methodology?

and, accusing people of attempting to help you get...

2010-08-27T04:25:23.958-05:00

and, accusing people of attempting to help you get your tool placed into the most appropriate place (it's certainly /not/ an Ubuntu development tool) of bikeshedding is a great way to demotivate them. Nice one.

You really shouldn't use such generic names; i...

2010-08-27T04:22:03.736-05:00

You really shouldn't use such generic names; it's probably best to namespace them instead: $namespace-1..9. Otherwise, that's a good idea.

In general, its a good idea to avoid eval. Below ...

2010-08-26T22:27:19.866-05:00

In general, its a good idea to avoid eval. Below is a solution without eval. Before you get on my case and tell me that '${2:+}' didn't work in some ancient versions of /bin/sh, i don't really care. If you do, change it to /bin/bash.

Second thing i like is it doesn't rely on being named something specific. 'fno' or 'field number' requires input of a field. you can then easily set up aliases to pass it that field, as shown below.

$ cat ~/bin/fno
#!/bin/sh
# arg1=field number # arg2 = optional field separator
[ -n "${1}" -a "${1#[0-9]}" != "${1}" ] ||
{ echo "bad input to ${0##*/}: $*" 1>&2; exit 1; }
exec awk ${2:+"-F${2}"} '{print $'"$1"'}'

$ for x in $(seq 1 9); do alias $x="fno $x"; done
$ echo "one two three four five" | fno 5
five
$ echo "one two three four five" | 4
four
$ echo "one:two:three:four:five" | 2

$ echo "one:two:three:four:five" | 2 :
two

Evil how? Did you try it?

2010-08-26T21:10:08.899-05:00

Evil how? Did you try it?

This looks evil.. glad you aptly labeled it as a &...

2010-08-26T21:03:30.399-05:00

This looks evil.. glad you aptly labeled it as a "hack" :)