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This article mainly explains "how Python executes the commands of the Linux operating system". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how Python executes the commands of the Linux operating system".

In the process of developing OPS scripts, you often need to execute some operating system commands, and the common methods are as follows:

1. Use os.system

> import os

> cmd ='ls /'

> res = os.system (cmd)

Bin boot data dev etc home lib lib64 media mnt opt oracle proc root run sbin srv sys tmp usr var

> print (res)

0

Features:

(1) Python built-in method, which returns 0 after successful execution, and prints the result of command execution in standard output.

(2) cannot return the running result of the command

2. Use commands.getstatusoutput

> import os commands

> cmd ='ls /'

> status,output = commands.getstatusoutput (cmd)

Status is the status of command execution. It returns 0 for success and non-0 for error.

Output is the result of the execution of a command

Features:

(1) commands can only be used in Python2.x version, and not every Python2.x version comes with this module.

(2) commands package has been discarded in Python3

3. Use subprocess.Popen

> > from subprocess import Popen, PIPE

> process = Popen (cmd, shell=True, stdout=PIPE, stderr=PIPE)

> stdout, stderr = process.communicate ()

Stdout is the result of command execution, and stderr is the command error message. Note that even if some commands are executed successfully, there will be an error message, but the result will not be affected.

Features:

(1) Python2.x and Python3.x built-in modules

(2) the command execution result and error message can be returned at the same time

(3) you can get the exit code of the command.

To sum up, the third method is recommended.

A function that executes operating system commands can be encapsulated as follows, supporting the execution of remote node commands based on mutual trust, and returning annotation output, annotation errors and exit codes.

From subprocess import Popen, PIPE

Def exec_command (shell_cmd, hostname=None):

If hostname:

P = Popen ('/ usr/bin/ssh-Tq'+ hostname, shell=True, stdout=PIPE, stdin=PIPE)

P.stdin.write (str.encode (shell_cmd))

P.stdin.flush ()

Else:

P = Popen (shell_cmd, shell=True, stdout=PIPE, stdin=PIPE)

Stdout, stderr = p.communicate ()

If stdout:

Stdout = stdout.decode ()

If stderr:

Stderr = stderr.decode ()

Return stdout, stderr, p.poll ()

Thank you for reading, the above is the content of "how Python executes the commands of the Linux operating system". After the study of this article, I believe you have a deeper understanding of how Python executes the commands of the Linux operating system, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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