Bug #1287: $? not set after Open3::popen3

• Status: Rejected
• Assignee: -
• Target version: 1.9.1
• ruby -v: ruby 1.9.1p0 (2009-01-30 revision 21907) [i686-linux]

[phasis68 (Heesob Park)]

=begin
$? is not set after popen3 in 1.9.1

Try following code:

require 'open3'
status = Open3::popen3("echo hello") do |stdin,stdout,stderr|
stdout.each { |line| puts "stdout:"+line }
end
p $?

[sidns@ns ~]$ ruby -v po.rb
ruby 1.8.6 (2007-09-24 patchlevel 111) [i686-linux]
stdout:hello
#<Process::Status: pid=20140,exited(0)>

[siweb@localhost ~]$ ruby -v po.rb
ruby 1.9.1p0 (2009-01-30 revision 21907) [i686-linux]
stdout:hello
nil
=end

[akr (Akira Tanaka)]

• Status changed from Open to Rejected

=begin
ruby 1.8 don't have a way to know the exit status because double fork is used.

$? doesn't reflect the actual status.

% ruby-1.8.6p287 -ropen3 -ve '
status = Open3::popen3("echo hello;exit 1") do |stdin,stdout,stderr|
stdout.each { |line| puts "stdout:"+line }
end
p $?'
ruby 1.8.6 (2008-08-11 patchlevel 287) [i686-linux]
stdout:hello
#<Process::Status: pid=31667,exited(0)>

open3 in ruby 1.9 has the fourth argument, wait thread, to the block.
The thread wait the child process and returns the exit status as the value of the thread.

% ruby-1.9.1p0 -ropen3 -ve '
status = Open3::popen3("echo hello;exit 1") do |stdin,stdout,stderr,waitth|
stdout.each { |line| puts "stdout:"+line }
p waitth.value
end
'
ruby 1.9.1p0 (2009-01-30 revision 21907) [i686-linux]
stdout:hello
#<Process::Status: pid 31847 exit 1>

=end

[schneems (Richard Schneeman)]

FWIW the work around is to capture the status and re-exec with an exit. It works, but the downside is that shell invocations are not cheap:

irb(main):042:0> a, b, c = Open3.capture3("ls /does/not/exist")
irb(main):043:0> `exit #{c.exitstatus}`
=> ""
irb(main):044:0> $?
=> #<Process::Status: pid 78179 exit 1>