python标准库介绍——36 popen2 模块详解

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==popen2 模块==     ``popen2`` 模块允许你执行外部命令, 并通过流来分别访问它的 ``stdin`` 和 ``stdout`` ( 可能还有 ``stderr`` ).   在 python 1.5.2 以及之前版本, 该模块只存在于 Unix 平台上. 2.0 后, Windows 下也实现了该函数. [Example 3-9 #eg-3-9] 展示了如何使用该模块来给字符串排序.   ====Example 3-9. 使用 popen2 模块对字符串排序Module to Sort Strings====[eg-3-9]   ``` File: popen2-example-1.py   import popen2, string   fin, fout = popen2.popen2("sort")   fout.write("foo\n") fout.write("bar\n") fout.close()   print fin.readline(), print fin.readline(), fin.close()   *B*bar foo*b* ```   [Example 3-10 #eg-3-10] 展示了如何使用该模块控制应用程序 .   ====Example 3-10. 使用 popen2 模块控制 gnuchess====[eg-3-10]   ``` File: popen2-example-2.py   import popen2 import string   class Chess:     "Interface class for chesstool-compatible programs"       def _ _init_ _(self, engine = "gnuchessc"):         self.fin, self.fout = popen2.popen2(engine)         s = self.fin.readline()         if s != "Chess\n":             raise IOError, "incompatible chess program"       def move(self, move):         self.fout.write(move + "\n")         self.fout.flush()         my = self.fin.readline()         if my == "Illegal move":             raise ValueError, "illegal move"         his = self.fin.readline()         return string.split(his)[2]       def quit(self):         self.fout.write("quit\n")         self.fout.flush()   # # play a few moves   g = Chess()   print g.move("a2a4") print g.move("b2b3")   g.quit()   *B*b8c6 e7e5*b* ```