Invoking a script, which has an awk shebang, with parameters (vars)

Question

I have an awk script that I have defined thusly:

#!/usr/bin/env awk
BEGIN { if (!len) len = 1; end = start + len }
{ for (i = start; i < end; i++) { print $1 } }

I have saved it as columns and chmod +x'd it. I want invoke it so that start and end are defined as it traverses over a file. I was thinking this should work:

cat some_file | columns -v start=2

But it doesn't. Help!

Answer 1

Try using:

#!/usr/bin/awk -f

as an interpreter

Answer 2

What do you mean "it doesn't work"? Other than the fact that I had to add a -f to the shebang, it works fine for me:

#!/usr/bin/env awk -f

The trouble may be that your program behaves exactly the same regardless of the value of start, printing the first field len times.