Python子进程调用Unix命令，关于如何存储输出的问题

发布于 2024-10-26 20:45:56 字数 417 浏览 2 评论 0原文

我正在编写一个 python 脚本，它读取行/字符串，调用 Unix，使用 grep 在查询文件中搜索包含该字符串的行，然后打印结果。

from subprocess import call

for line in infilelines:

    output = call(["grep", line, "path/to/query/file"])
    print output
    print line`

当我查看打印到屏幕上的结果时，我将从查询文件中获取匹配字符串的列表，但我会还得到“1”和“0”整数作为输出，并且 line 永远不会打印到屏幕上。我希望从查询文件中获取与我的字符串匹配的行，后跟我在搜索中使用的字符串。

原文

I am writing a python script that reads a line/string, calls Unix, uses grep to search a query file for lines that contain the string, and then prints the results.

from subprocess import call

for line in infilelines:

    output = call(["grep", line, "path/to/query/file"])
    print output
    print line`

When I look at my results printed to the screen, I will get a list of matching strings from the query file, but I will also get "1" and "0" integers as output, and line is never printed to the screen. I expect to get the lines from the query file that match my string, followed by the string that I used in my search.

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汹涌人海 2024-11-02 20:45:56

调用返回进程返回码。

如果使用 Python 2.7，请使用 check_output。

from subprocess import check_output
output = check_output(["grep", line, "path/to/query/file"])

如果在此之前使用任何内容，请使用通信。

import subprocess
process = subprocess.Popen(["grep", line, "path/to/query/file"], stdout=subprocess.PIPE)
output = process.communicate()[0]

这将打开一个标准输出管道，您可以通过通信来读取它。如果您也想要 stderr，则还需要添加“stderr=subprocess.PIPE”。

这将返回完整的输出。如果您想将其解析为单独的行，请使用 split。

output.split('\n')

我相信Python会为你处理行结束转换，但由于你使用的是grep，我将假设你在Unix上，行结束无论如何都是\n。

http://docs.python.org/library/subprocess.html#subprocess.check_output

call returns the process return code.

If using Python 2.7, use check_output.

from subprocess import check_output
output = check_output(["grep", line, "path/to/query/file"])

If using anything before that, use communicate.

import subprocess
process = subprocess.Popen(["grep", line, "path/to/query/file"], stdout=subprocess.PIPE)
output = process.communicate()[0]

This will open a pipe for stdout that you can read with communicate. If you want stderr too, you need to add "stderr=subprocess.PIPE" too.

This will return the full output. If you want to parse it into separate lines, use split.

output.split('\n')

I believe Python takes care of line-ending conversions for you, but since you're using grep I'm going to assume you're on Unix where the line-ending is \n anyway.

http://docs.python.org/library/subprocess.html#subprocess.check_output

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盗心人 2024-11-02 20:45:56

以下代码适用于 Python >= 2.5：

from commands import getoutput
output = getoutput('grep %s path/to/query/file' % line)
output_list = output.splitlines()

The following code works with Python >= 2.5:

from commands import getoutput
output = getoutput('grep %s path/to/query/file' % line)
output_list = output.splitlines()

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巡山小妖精 2024-11-02 20:45:56

当 Python 本身可以执行对外部 grep 的调用时，为什么要执行呢？这是额外的开销，您的代码将依赖于安装的 grep。这就是在 Python 中使用“in”运算符执行简单 grep 的方法。

query=open("/path/to/query/file").readlines()
query=[ i.rstrip() for i in query ]
f=open("file")
for line in f:
    if "line" in query:
        print line.rstrip()
f.close()

Why would you want to execute a call to external grep when Python itself can do it? This is extra overhead and your code will then be dependent on grep being installed. This is how you do simple grep in Python with "in" operator.

query=open("/path/to/query/file").readlines()
query=[ i.rstrip() for i in query ]
f=open("file")
for line in f:
    if "line" in query:
        print line.rstrip()
f.close()

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