Python:subprocess.popen:读取每行输出

Question

我无法逐行读取子进程输出.子进程只是将文件的内容与另一个文件进行对比.输出应该是一个两列文件,打印到stdout就好了.但是当我尝试读取每一行时,它会读取每个字符后跟\n:

#!/usr/bin/python    

import sys
import getopt
import os
import subprocess
from subprocess import Popen, PIPE, STDOUT

inputfile = ''
target = ''

try:
        opts, args = getopt.getopt(sys.argv[1:],"s:t:",['servers=', 'target='])
except getopt.GetoptError:
        print 'getopt failure: exit'
        sys.exit()

for opt, arg in opts:
        if opt in ("-s", "--servers"):
                inputfile = arg
        if opt in ("-t", "--target"):
                boxwin = arg

p1 = subprocess.Popen(["grep -f " + inputfile + " " + target + " | awk '{print $2, $1}'"], stdout=subprocess.PIPE, shell=True)

output, error = p1.communicate()

print output # this prints normally

for line in output:
        print line # this prints each char of output followed by \n???

逐行读取后的预期输出:

abc 123
def 456
ghi 789

如果我只是"打印输出",这将打印

使用for循环读取每一行时的实际输出:

a
b
c

1
2
3

d
e
f

...

有任何想法吗？谢谢.

Answer 1

请尝试以下方法:

for line in output.split(os.linesep):

代替:

for line in output:

Answer 2

for c in s:从字符串中读取一个字符s(应该如此).要从字符串中获取行列表,可以使用.splitlines()方法:

lines = output.splitlines()

您无需调用.communicate()逐行读取输出:

p = subprocess.Popen(cmd, stdout=PIPE)
for line in p.stdout:
    # do something with a line

您可以修改代码以不同方式处理缓冲或启用通用换行支持.