Ed is the standard editor.

-rob


On Tue, Mar 30, 2021 at 1:36 AM Larry McVoy <lm@mcvoy.com> wrote:

> I had *.clients.your-server.de crawling mcvoy.com in violation of my
> robots.txt.  For whatever reason, the tty settings (or something)
> made vi not work, I dunno what the deal is, stty -tabs didn't help.
>
> So I had to resort to ed to write and debug the little program below.
> It was surprisingly pleasant, it's probably the first time I've used ed
> for anything real in at least a decade.  My fingers still know it.
>
> +1 for ed.  It's how many decades old and still useful?
>
>
> #!/usr/libexec/bitkeeper/bk tclsh
>
> int
> main(void)
> {
>         FILE    log = popen("/var/log/apache2/dns.l", "r");
>         string  buf, ip;
>         string  dropped{string};
>
>         fconfigure(log, buffering: "line");
>         while (buf = <log>) {
>                 unless (buf =~ /([^ ]+\.your-server\.de\.) /) continue;
>                 ip = $1;
>                 if (defined(dropped{ip})) continue;
>                 dropped{ip} = "yes";
>                 warn("DROP ${ip}\n");
>                 system("/sbin/iptables -I INPUT -s ${ip} -j DROP");
>         }
> }
>