[SOLVED] awk command in a shell script with a user-defined function

Quakeboy02 · 04-12-2014, 12:56 AM

As you can see from the following, I'm trying to combine two different things, and I don't know how to even get started. What I need to do is run the awk command, which needs to run the function f() which is listed above it, which uses a control variable listed above that. The function is a phase rotation function, not that that contributes anything to the question. How do I combine these into a working script; whether shell or awk or perl or whatever? I've never had enough need for scripting to learn anything other than simple shell stuff.

Code:

#!/bin/sh
offset=72
function f(x) { x > $offset ? x-$offset-1 : x+100-$offset-1}

awk '{print f($17)" "strtonum($14)}'  fll.dat | sort -g | uniq  > phase.dat

rknichols · 04-12-2014, 09:58 AM

You just put all of the awk statements within the program text on the command line:

Code:

awk 'BEGIN { offset = 72 }
     function f(x) { return (x > offset ? x-offset-1 : x+100-offset-1) }
     { print f($17)" "strtonum($14) }' fll.dat | sort -g | uniq  > phase.dat

I've broken up the awk statements on multiple lines for readability. You can leave them that way, or smoosh them all together on one line -- your choice, makes no difference.

You could also pass that offset value in as a parameter rather than setting it in the BEGIN block. That way it could be a shell variable:

Code:

#!/bin/bash
Offset=72
awk -v offset=$Offset 'function f(x) { return (x > offset ? x-offset-1 : x+100-offset-1) }
       { print f($17)" "strtonum($14) }' fll.dat | sort -g | uniq  > phase.dat

Quakeboy02 · 04-12-2014, 10:20 AM

Thanks! I figured the function had to be part of the awk statement, but couldn't find any examples of how to do that. Easy once you showed me. I chose the second one using the bash variable "Offset". It worked first try. That gives me a lot to work with in future efforts, as well. Cheers!