okkez です。

バージョンによって返す値が違うみたいです。

    pid = fork {
      # child
      sleep 3
    }

    p pid
    th = Process.detach(pid)
    p th.value

ruby 1.8.0 (2003-08-04) [x86_64-linux]
6815
nil
ruby 1.8.1 (2003-12-25) [x86_64-linux]
6817
nil
ruby 1.8.2 (2004-12-25) [x86_64-linux]
6821
nil
ruby 1.8.3 (2005-09-21) [x86_64-linux]
6824
nil
ruby 1.8.4 (2005-12-24) [x86_64-linux]
6827
nil
ruby 1.8.5 (2008-06-20 patchlevel 231) [x86_64-linux]
6831
#<Process::Status: pid=6831,exited(0)>
ruby 1.8.6 (2009-09-09 patchlevel 388) [x86_64-linux]
6834
#<Process::Status: pid=6854,exited(0)>
ruby 1.8.7 (2011-02-18 patchlevel 334) [x86_64-linux]
6857
#<Process::Status: pid=6857,exited(0)>
ruby 1.8.8dev (2010-08-05 revision 26865) [x86_64-linux]
6860
#<Process::Status: pid=6860,exited(0)>
ruby 1.9.1p378 (2010-01-10 revision 26273) [x86_64-linux]
6872
#<Process::Status: pid 6872 exit 0>
ruby 1.9.1p429 (2010-07-14 revision 28641) [x86_64-linux]
6879
#<Process::Status: pid 6879 exit 0>
ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
6911
#<Process::Status: pid 6911 exit 0>
ruby 1.9.2p136 (2010-12-25 revision 30365) [x86_64-linux]
6942
#<Process::Status: pid 6942 exit 0>
ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-linux]
6975
#<Process::Status: pid 6975 exit 0>
ruby 1.9.3dev (2011-05-17 trunk 31610) [x86_64-linux]
6981
#<Process::Status: pid 6981 exit 0>

-- 
okkez
okkez000@g...

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