python commands模块在python3.x被subprocess取代

subprocess

可以执行shell命令的相关模块和函数有：

os.system
os.spawn
os.popen --废弃
popen2.* --废弃
commands.* --废弃，3.x中被移除

import commands

result = commands.getoutput(‘cmd‘)　　　＃只返回执行的结果, 忽略返回值.
result = commands.getstatus(‘cmd‘)　　　＃返回ls -ld file执行的结果.
result = commands.getstatusoutput(‘cmd‘)　

＃用os.popen()执行命令cmd, 然后返回两个元素的元组(status, result). cmd执行的方式是{ cmd ; }2>&1, 这样返回结果里面就会包含标准输出和标准错误.

例子

>>> subprocess.getstatusoutput(‘pwd‘)(0, ‘/home/ronny‘)>>> subprocess.getoutput(‘pwd‘)‘/home/ronny‘>>> subprocess.getstatus(‘pwd‘)Traceback (most recent call last):  File "<stdin>", line 1, in <module>AttributeError: module ‘subprocess‘ has no attribute ‘getstatus‘

以上执行shell命令的相关的模块和函数的功能均在 subprocess 模块中实现，并提供了更丰富的功能。

(1) call

执行命令，返回状态码(命令正常执行返回0，报错则返回1)

ret1=subprocess.call("ifconfig")
ret2=subprocess.call("ipconfig")　　　　#python3.5不是这样，依然会抛出异常导致无法对ret2赋值
print(ret1)     #0
print(ret2)     #1

ret = subprocess.call(["ls", "-l"], shell=False)    #shell为False的时候命令必须分开写
ret = subprocess.call("ls -l", shell=True)

(2) check_call

执行命令，如果执行成功则返回状态码0，否则抛异常

subprocess.check_call(["ls", "-l"])
subprocess.check_call("exit 1", shell=True)

(3) check_output

执行命令，如果执行成功则返回执行结果，否则抛异常

subprocess.check_output(["echo", "Hello World!"])
subprocess.check_output("exit 1", shell=True)

(4) subprocess.Popen(...)

用于执行复杂的系统命令

import subprocess
ret1 = subprocess.Popen(["mkdir","t1"])
ret2 = subprocess.Popen("mkdir t2", shell=True)

终端输入的命令分为两种：

1. 输入即可得到输出，如：ifconfig
2. 输入进行某环境，依赖再输入，如：python

import subprocess

obj = subprocess.Popen("mkdir t3", shell=True, cwd=‘/home/dev‘,)     #在cwd目录下执行命令

import subprocess

obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
obj.stdin.write("print(1)\n")
obj.stdin.write("print(2)")
obj.stdin.close()

cmd_out = obj.stdout.read()
obj.stdout.close()
cmd_error = obj.stderr.read()
obj.stderr.close()

print(cmd_out)
print(cmd_error)

import subprocess

obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
obj.stdin.write("print(1)\n")
obj.stdin.write("print(2)")

out_error_list = obj.communicate()
print(out_error_list)

import subprocess

obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
out_error_list = obj.communicate(‘print("hello")‘)
print(out_error_list)