pipes — Interface to shell pipelines外壳管道接口

Source code: Lib/pipes.py

Deprecated since version 3.11: The pipes module is deprecated (see PEP 594 for details).管道模块已弃用（详见PEP 594）。

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The pipes module defines a class to abstract the concept of a pipeline — a sequence of converters from one file to another.pipes模块定义了一个类来抽象管道的概念——从一个文件到另一个文件的转换器序列。

Because the module uses /bin/sh command lines, a POSIX or compatible shell for os.system() and os.popen() is required.由于模块使用/bin/sh命令行，因此需要一个POSIX或os.system()和os.popen()的兼容shell。

Availability: Unix. Not available on VxWorks.可用性：Unix。VxWorks上不可用。

The pipes module defines the following class:pipes模块定义以下类：

classpipes.Template

An abstraction of a pipeline.管道的抽象。

Example:例子：

>>> import pipes
>>> t = pipes.Template()
>>> t.append('tr a-z A-Z', '--')
>>> f = t.open('pipefile', 'w')
>>> f.write('hello world')
>>> f.close()
>>> open('pipefile').read()
'HELLO WORLD'

Template Objects模板对象

Template objects following methods:使用以下方法创建模板对象：

Template.reset()

Restore a pipeline template to its initial state.将管道模板恢复到其初始状态。

Template.clone()

Return a new, equivalent, pipeline template.返回新的等效管道模板。

Template.debug(flag)

If flag is true, turn debugging on. 如果flag为true，则打开调试。Otherwise, turn debugging off. When debugging is on, commands to be executed are printed, and the shell is given set -x command to be more verbose.否则，关闭调试。当调试打开时，将打印要执行的命令，并为shell提供set -x命令以使其更加详细。

Template.append(cmd, kind)

Append a new action at the end. 在末尾附加一个新动作。The cmd variable must be a valid bourne shell command. cmd变量必须是有效的bourne shell命令。The kind variable consists of two letters.kind变量由两个字母组成。

The first letter can be either of '-' (which means the command reads its standard input), 'f' (which means the commands reads a given file on the command line) or '.' (which means the commands reads no input, and hence must be first.)第一个字母可以是'-'（表示命令读取其标准输入）、'f'（表示该命令读取命令行上的给定文件）或'.'（这意味着命令没有读取输入，因此必须是第一个。）

Similarly, the second letter can be either of '-' (which means the command writes to standard output), 'f' (which means the command writes a file on the command line) or '.' (which means the command does not write anything, and hence must be last.)类似地，第二个字母可以是'-'（表示命令写入标准输出）、'f'（表示该命令在命令行上写入文件）或'.'（这意味着命令不写任何内容，因此必须是最后一个。）

Template.prepend(cmd, kind)

Add a new action at the beginning. 在开头添加新操作。See append() for explanations of the arguments.有关参数的解释，请参阅append()。

Template.open(file, mode)

Return a file-like object, open to file, but read from or written to by the pipeline. 返回一个类似于文件的对象，该对象打开到file，但由管道读取或写入。Note that only one of 'r', 'w' may be given.请注意，只能给出'r'、'w'中的一个。

Template.copy(infile, outfile)

Copy infile to outfile through the pipe.通过管道复制infile到outfile。