導語

在編寫python腳本的時候，偶爾想調用shell命令來執行一些操作會比較方便些。python中目前有多種方法可以達到這樣的目的，有的僅僅是執行命令不返回需要的結果，有些可以返回執行的結果保存到變量，以便于后續操作

涉及到的模塊有 os.system、commands、subprocess

下面以具體的例子說明情況

#!/usr/bin/env bash 

import os
import commands
import subprocess

# -- os.system() --
# execute shell command in sub-terminal and can not get the return result
result1 = os.system('ls -l .')
print('result: ')
print(result1)
print('----------------------------------------')

# -- os.popen() --
# execute and can get the return result
result2 = os.popen('ls -l')
# file type
print('type: ', type(result2))

result3 = os.popen('ls -l').readlines()
# list file
print('type: ', type(result3))
print('result: ')
print(result3)
print('----------------------------------------')

# -- commands --
# import commands
# method:
#   getoutput
#   getstatusoutput
result4 = commands.getoutput('ls -l')
print('result: ')
print(result4)
print('=======')
result5_status, result5_output = commands.getstatusoutput('ls -l')
print('status: ', result5_status)
print('output: ')
print(result5_output)
print('----------------------------------------')



# subprocess
# import subprocess
# method:
#   call(["cmd","arg1", "arg2"], shell=True) refer to os.system()
#   Popen("cmd", shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT) refer to os.popen
#
#result6 = subprocess.call("ls -l", shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
p = subprocess.Popen('ls *.txt', shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
print(p.stdout.readlines())

for line in p.stdout.readlines():
    print line,

## wait for child process to terminate, and turn returncode
retval = p.wait()
##  if ok, return 0
print(retval)