How to call Linux commands in Python

First, using the OS module

In [1]:ImportOs#Import OS moduleIn [2]: Os.system ('ls') Anaconda-Ks.cfgepel-release-7-5. Noarch.rpmipython-4.1.2Ipython-4.1.2. Tar.gzpip-8.1.2Pip-8.1.2.tar.gz#md5=87083c0b9867963b29f7aba3613e8f4a.gzout[2]: 0In [3]: A=os.system ('ls')##得到的是执行的命令的返回值, not the result of executionAnaconda-Ks.cfgepel-release-7-5. Noarch.rpmipython-4.1.2Ipython-4.1.2. Tar.gzpip-8.1.2Pip-8.1.2.tar.gz#md5=87083c0b9867963b29f7aba3613e8f4a.gzIn [4]: A#executes the return value of the LS command, succeeds, 0out[4]: 0In [5]: B=os.popen ('ls'). ReadLines ()#assign the resulting results directly to the B listIn [6]: b#ls execution output to memory, then read all assigned to B listout[6]:['anaconda-ks.cfg\n', 'epel-release-7-5.noarch.rpm\n', 'ipython-4.1.2\n', 'ipython-4.1.2.tar.gz\n', 'pip-8.1.2\n', 'pip-8.1.2.tar.gz#md5=87083c0b9867963b29f7aba3613e8f4a.gz\n']

Common methods in >>>os modules (Linux commands)

Os.remove (): Delete file

Os.rename (): Rename file

Os.walk (): Generate all file names under the directory tree

Os.chdir (): Change Directory

Os.mkdir/makedirs: Creating a Directory/multi-level directory

Os.rmdir/removedirs: Delete directory/multi-level directory

Os.listdir (): Lists files for the specified directory

OS.GETCWD (): Get current working directory

Os.chmod (): Change directory Permissions

Os.path.basename (): Remove directory path, return file name

Os.path.dirname (): Remove file name, return directory path

Os.path.join (): Combines the parts of the separation into one path name

Os.path.getsize (): Return file size

Os.path.exists (): Presence

Os.path.isabs (): is an absolute path

Os.path.isdir (): Whether it is a directory

Os.path.isfile (): Whether it is a file

Second, using the commands module

In [7]:ImportCommands#Import Commands ModuleIn [8]: C=commands.getoutput ('ls')#ls command execution result, string form assignment to c variableIn [9]: cout[9]:'anaconda-ks.cfg\nepel-release-7-5.noarch.rpm\nipython-4.1.2\nipython-4.1.2.tar.gz\npip-8.1.2\ Npip-8.1.2.tar.gz#md5=87083c0b9867963b29f7aba3613e8f4a.gz'In [Ten]: D=c.split ('\ n')#for variable C, specify the delimiter \ n Delimited, the list is assigned to DIn [11]: dout[11]:['anaconda-ks.cfg', 'epel-release-7-5.noarch.rpm', 'ipython-4.1.2', 'ipython-4.1.2.tar.gz', 'pip-8.1.2', 'pip-8.1.2.tar.gz#md5=87083c0b9867963b29f7aba3613e8f4a.gz']

Three, read, ReadLine, ReadLines difference

1. Read () All out, put in a string

2. The ReadLine () method will read the contents of the memory space one line at a time and put it in a string

3. The ReadLines () method will take the contents of the memory space all at once and put it in a list.

Iv. Python scripting practices

1, write a Python script to implement the output of all users of Linux information, the format is as follows:

Username is the root uid is 0

Username is Xiaojin UID is 200

Username is bin UID is 10

Way One:

#!/usr/bin/pythonImportCommandsuser_str=commands.getoutput ('cat/etc/passwd') User_list=user_str.splitlines ()#List-delimited file contents (default by Row) forIinchUser_list:u_info=i.split (':')Print "username is", U_info[0],"UID is", U_info[2]

Way two:

#!/usr/bin/pythonImportOsuserlines=os.popen ("cat/etc/passwd"). ReadLines () forIinchUserlines:user_info=i.split (":")Print "username is", User_info[0],"\tuid is", User_infO[2]

2. Numerical script

1. Alert the user that the input content range is 0-100

2. Judge what the user entered, if not a number to give a reminder

3. Output user input

#!/usr/bin/pythonU_grade=raw_input ("Please input your grade:")ifU_grade.isdigit ():#IsDigit () method to convert a string to a percentageif0<=int (U_grade) <=100:Print "your grade is", U_gradeElse:Print "Please input the range of number 0-100"Else:Print "It ' s not a valid number,try again"

How to call Linux commands in Python