Examples in README fail

[koudelka]

Looks like subexec's timeout functionality doesn't work unless you specify a logfile.

In https://github.com/nulayer/subexec/blob/master/lib/subexec.rb#L80, #readlines blocks.

$ time ruby -r subexec -e 'Subexec.run "echo 'hello' && sleep 3", :timeout => 1'
0.30s user 0.06s system 10% cpu 3.369 total

[koudelka]

IO#readlines blocks until #close is called on all the handles to the write side of the pipe, a long-running subprocess doesn't close its handle on the pipe until it exits, so the timeout loop gets jammed up there.

You might want to use IO#select instead, it supports a read timeout.

A better solution might be to use IO#read_nonblock to try to read a single character.