From: Han Holl <han.holl@...>
Date: 2007-10-04T18:47:25+09:00
Subject: Signal handling strangeness (Linux)

 Hi,

The following program:

#!/usr/bin/ruby -w
IO.popen("tail -F --lines=0 --pid=#{Process.pid} /var/log/messages") do |h|
  while line = h.gets
    puts line
  end
end
# end-of-program

can be terminated with 'kill -TERM pid'.

This one:

#!/usr/bin/ruby -w
trap('TERM') do
  exit
end

IO.popen("tail -F --lines=0 --pid=#{Process.pid} /var/log/messages") do |h|
  while line = h.gets
    puts line
  end
end
# end-of-program

cannot. It hangs on a waitpid (or wait4) for the tail process.
Why is this ? And is it reasonable ?

Han Holl

PS Forgot to say: this is Linux.