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17 | <title>6.9.1 Popen3 and Popen4 Objects </title> | |
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55 | <H2><A NAME="SECTION008910000000000000000"></A><A NAME="popen3-objects"></A> | |
56 | <BR> | |
57 | 6.9.1 Popen3 and Popen4 Objects | |
58 | </H2> | |
59 | ||
60 | <P> | |
61 | Instances of the <tt class="class">Popen3</tt> and <tt class="class">Popen4</tt> classes have the | |
62 | following methods: | |
63 | ||
64 | <P> | |
65 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> | |
66 | <td><nobr><b><tt id='l2h-1849' xml:id='l2h-1849' class="method">poll</tt></b>(</nobr></td> | |
67 | <td><var></var>)</td></tr></table></dt> | |
68 | <dd> | |
69 | Returns <code>-1</code> if child process hasn't completed yet, or its return | |
70 | code otherwise. | |
71 | </dl> | |
72 | ||
73 | <P> | |
74 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> | |
75 | <td><nobr><b><tt id='l2h-1850' xml:id='l2h-1850' class="method">wait</tt></b>(</nobr></td> | |
76 | <td><var></var>)</td></tr></table></dt> | |
77 | <dd> | |
78 | Waits for and returns the status code of the child process. The | |
79 | status code encodes both the return code of the process and | |
80 | information about whether it exited using the <tt class="cfunction">exit()</tt> | |
81 | system call or died due to a signal. Functions to help interpret the | |
82 | status code are defined in the <tt class="module"><a href="module-os.html">os</a></tt> module; see section | |
83 | <A href="os-process.html#os-process">6.1.5</A> for the <tt class="function">W<var>*</var>()</tt> family of functions. | |
84 | </dl> | |
85 | ||
86 | <P> | |
87 | The following attributes are also available: | |
88 | ||
89 | <P> | |
90 | <dl><dt><b><tt id='l2h-1851' xml:id='l2h-1851' class="member">fromchild</tt></b></dt> | |
91 | <dd> | |
92 | A file object that provides output from the child process. For | |
93 | <tt class="class">Popen4</tt> instances, this will provide both the standard output | |
94 | and standard error streams. | |
95 | </dl> | |
96 | ||
97 | <P> | |
98 | <dl><dt><b><tt id='l2h-1852' xml:id='l2h-1852' class="member">tochild</tt></b></dt> | |
99 | <dd> | |
100 | A file object that provides input to the child process. | |
101 | </dl> | |
102 | ||
103 | <P> | |
104 | <dl><dt><b><tt id='l2h-1853' xml:id='l2h-1853' class="member">childerr</tt></b></dt> | |
105 | <dd> | |
106 | A file object that provides error output from the child process, if | |
107 | <var>capturestderr</var> was true for the constructor, otherwise | |
108 | <code>None</code>. This will always be <code>None</code> for <tt class="class">Popen4</tt> | |
109 | instances. | |
110 | </dl> | |
111 | ||
112 | <P> | |
113 | <dl><dt><b><tt id='l2h-1854' xml:id='l2h-1854' class="member">pid</tt></b></dt> | |
114 | <dd> | |
115 | The process ID of the child process. | |
116 | </dl> | |
117 | ||
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