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# 36.16. `commands` — Utilities for running commands

2.6 版后已移除: The `commands` module has been removed in Python 3. Use the `subprocess` module instead.

The `commands` module contains wrapper functions for `os.popen()` which take a system command as a string and return any output generated by the command and, optionally, the exit status.

The `subprocess` module provides more powerful facilities for spawning new processes and retrieving their results. Using the `subprocess` module is preferable to using the `commands` module.

注解

In Python 3.x, `getstatus()` and two undocumented functions (`mk2arg()` and `mkarg()`) have been removed. Also, `getstatusoutput()` and `getoutput()` have been moved to the `subprocess` module.

The `commands` module defines the following functions:

`commands.``getstatusoutput`(cmd)

  Execute the string cmd in a shell with `os.popen()` and return a 2-tuple `(status, output)`. cmd is actually run as `{ cmd ; } 2>&1`, so that the returned output will contain output or error messages. A trailing newline is stripped from the output. The exit status for the command can be interpreted according to the rules for the C function `wait()`.

`commands.``getoutput`(cmd)

  Like `getstatusoutput()`, except the exit status is ignored and the return value is a string containing the command’s output.

`commands.``getstatus`(file)

  Return the output of `ls -ld file` as a string. This function uses the `getoutput()` function, and properly escapes backslashes and dollar signs in the argument.

  2.6 版后已移除: This function is nonobvious and useless. The name is also misleading in the presence of `getstatusoutput()`.

Example:

    >>> import commands
    >>> commands.getstatusoutput('ls /bin/ls')
    (0, '/bin/ls')
    >>> commands.getstatusoutput('cat /bin/junk')
    (256, 'cat: /bin/junk: No such file or directory')
    >>> commands.getstatusoutput('/bin/junk')
    (256, 'sh: /bin/junk: not found')
    >>> commands.getoutput('ls /bin/ls')
    '/bin/ls'
    >>> commands.getstatus('/bin/ls')
    '-rwxr-xr-x  1 root        13352 Oct 14  1994 /bin/ls'

参见

Module `subprocess`

  Module for spawning and managing subprocesses.