[PhilipRoman]

I find it pretty nice for writing simple preprocessors. For example I have one which takes anything between two marker lines and pipes it through a command (one invocation per block). Awk has an amazing pipe operator which lets you do something like this:

    ... {
        print $0 | "command"
    }

"command" is executed once, and the pipe is kept open until closed explicitly by close("command"), at which point the next invocation will execute it again. The command string itself acts as a key for the pipe file descriptor.

And of course, no mention of awk is complete without the "uniq" implementation, which beats the coreutils uniq in every way possible (by supporting arbitrary expressions as keys and not requiring sorted input):

    !a[$0]++

[aktau]

I had no idea about this "keep the pipe open" behaviour. I thought it would spawn the binary on every print statement and thus didn't consider it in the past. But now...