Re: awk and fflush()/-W interactive

[Thorsten Wißmann <edu _at_ thorsten _minus_ wissmann _dot_ de>]

On Fri, Aug 16, 2013 at 10:49:24AM +0200, Florian Bruhin wrote:
> * Mono <mono _at_ posteo _dot_ de> [2013-08-16 08:04:56 +0200]:
> > how about having an sed command insert -W interactive during
> > installation, only if mawk is detected?  hmm, just an idea.
> 
> That sounds kind-of hacky, but it gave me a nice idea. What about
> something like this, in the actual script:
> 
>     if awk -Wv 2>/dev/null | head -1 | grep -q '^mawk'; then
>         awk_args=('-W' 'interactive')
>     else
>         awk_args=()
>     fi
>     # ...
>     awk "${awk_args[@]}" ...

Or even faster:

  if awk -Wv 2>/dev/null | head -1 | grep -q '^mawk'; then
      uniq_linebuffered() {
        awk -W interactive '$0 != l { print ; l=$0 ; fflush(); }' "$@"
      }
  else
      uniq_linebuffered() {
        awk '$0 != l { print ; l=$0 ; fflush(); }' "$@"
      }
  fi


> Though I should probably test how fflush() actually behaves for all
> these versions of awk.

Yes. Maybe there is some Posix specification.

Thorsten

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