### 4 os.spawn* を置き換える

P_NOWAIT の例:

    pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
    ==>
    pid = Popen(["/bin/mycmd", "myarg"]).pid

P_WAIT の例:

    retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
    ==>
    retcode = call(["/bin/mycmd", "myarg"])

シーケンスを使った例:

    os.spawnvp(os.P_NOWAIT, path, args)
    ==>
    Popen([path] + args[1:])

環境変数を使った例:

    os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
    ==>
    Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})