in reply to Automatically killing a child

See perlopentut for details, but note that piped-opens return the pid of the forked child. 

#!/usr/bin/perl
my $kid = open (HTML, "-|") or exec("tail","-f","testlog.txt");
print while <HTML>;
kill 2, $kid;

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You can use that to kill or wait or waitpid, but as tail -f file will never terminate* unless the file goes away, you will probably need to kill it.

That said, if the file never goes away, tail will never terminate, so your print while <HTML> will never get eof, so you will never exit that loop in order to try and use kill.

*those versions of tail I've used.

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