Hello,
I’m trying to run some simple commands using Kernel.exec but need to
capture the stderr for them. Is there an (easy) way to do it with
just ruby and the standard library or should I get open4?
Thanks,
-carl
On Sat, 9 Sep 2006, Carl L. wrote:
Hello,
I’m trying to run some simple commands using Kernel.exec but need to capture
the stderr for them. Is there an (easy) way to do it with just ruby and the
standard library or should I get open4?Thanks,
-carl
open4 adds quite a bit to open3, which is in the stdlib. so depending
on your
exact needs you may or may not need it.
however, by capture i assume you are on unix, since otherwise you cannot
fork
and exec just replaces the calling process so theres nothing to capture.
that
being the case you can just
out_err = ‘’
IO.popen("#{ cmd } 2>&1") do |pipe|
while((line = pipe.gets))
out_err << line
end
end
if you need to separate them you can do
require ‘open3’
stdout, stderr = ‘’, ‘’
Open3.popen3(cmd) do |i,o,e|
i.close
while((line = o.gets))
stdout << line
end
while((line = e.gets))
stderr << line
end
end
open4, as mentioned, does a whole lot more - check out the docs/samples.
regards.
-a
Carl L. wrote:
Hello,
I’m trying to run some simple commands using Kernel.exec but need to
capture the stderr for them. Is there an (easy) way to do it with
just ruby and the standard library or should I get open4?Thanks,
-carl
Kernel#exec never returns control; it replaces the ruby process with
the one you pass it. You need open3 (stdlib) or popen4.
[1] http://ruby-doc.org/stdlib/libdoc/open3/rdoc/index.html
[2] http://popen4.rubyforge.org/
Regards,
Jordan