How to use shell commands in Python, and how Python communicates with variables in the shell

1. There are several ways to use the shell command in Python, and I think it is better to use the commands module:

Import commands

A, B = commands.getstatusoutput ("Ls-al")

A is the exit state (int type), and B is the output of the shell command

Python--Shell:

1. Environment variables

Import OS
var=123 or var= ' 123 '
Os.environ[' var ']=str (Var) #environ的键值必须是字符串
Os.system (' echo $var ') or

A, B = commands.getstatusoutput ("$var")

2. String connection

Import OS
Path= '/root/a.txt '
VAR=[1]
var= ' Bash '
Os.system (' echo ' + path) #注意echo后有空格
Os.system (' echo ' + str (var[0]))
Os.system (' echo ' + var + '/root/c.sh ') #注意echo后和 a space before the/root

3. Through the pipeline

Import OS
Var= ' 123 '
Os.popen (' Wc-c ', ' W '). Write (Var)

4. Adoption of documents

Output = open ('/tmp/mytxt ', ' W ')
Output.write (S) #把字符串S写入文件
Output.writelines (L) #将列表L中所有的行字符串写到文件中
Output.close ()

5. Prepare the output by redirecting the target

BUF = open ('/root/a.txt ', ' W ')
Print >> buf, ' 123\n ', ' abc ' OR: Print >> open ('/root/a.txt ', ' W '), ' 123\n ', ' abc ' #写入或生成文件
Print >> open ('/root/a.txt ', ' a '), ' 123\n ', ' abc ' #追加

Shell-and Python:

1. Piping

Import OS
Var=os.popen (' echo-n 123 '). Read ()
Print Var

2.

Import commands
Var=commands.getoutput (' echo abc ') #输出结果
Var=commands.getstatusoutput (' echo abc ') #退出状态和输出结果

3. Documents

input = open ('/tmp/mytxt ', ' R ')
S = Input.read () #把整个文件读到一个字符串中
S = Input.readline () #读下一行 (over line end flag)
L = Input.readlines () #读取整个文件到一个行字符串的列表中