Parsing windows command results with Python and regex

Question

I am using the following code to ping a website to check for connectivity. How can I parse the results back to get "Lost = " to see how many were lost?

def pingTest():
    host = "www.wired.com"
    ping = subprocess.Popen(
        ["ping","-n","4",host],
        stdout = subprocess.PIPE,
        stderr = subprocess.PIPE
    )

    out,error = ping.communicate()
    print out

This is the return I get from out

Pinging wired.com [173.223.232.42] with 32 bytes of data:
Reply from 173.223.232.42: bytes=32 time=54ms TTL=51
Reply from 173.223.232.42: bytes=32 time=54ms TTL=51
Reply from 173.223.232.42: bytes=32 time=54ms TTL=51
Reply from 173.223.232.42: bytes=32 time=54ms TTL=51

Ping statistics for 173.223.232.42:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 54ms, Maximum = 54ms, Average = 54ms

How about if you also post just what string you get from 'out', since you have gone so far as to print it? — PaulMcG
– PaulMcG, Commented Feb 21, 2012 at 14:00

PaulMcG · Accepted Answer · 2012-02-21 14:06:45Z

7

Step 1: Construct a regular expression that will match Lost = 0 (0% loss), using \d tags to substitute for the numeric values, which will vary. Use capturing groups to preserve these values.

Step 2: Use re.search to scan the out string.

Step 3: Extract the values from the re's capturing groups.

answered Feb 21, 2012 at 14:06

PaulMcG

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1 Comment

Jesse Smith Over a year ago

Give a man a regex, and he will parse for a day. Teach a man to regex, and he'll parse for a lifetime! Good answer!

Niek de Klein · Accepted Answer · 2012-02-21 15:50:17Z

3

lost = out.split('Lost = ')[1].split(',')[0]

If you do this with your example, lost would contain 0 (0% loss)

If you want just the total you can do

lostTotal = out.split('Lost = ')[1].split(' ')[0]

If you want the percentage you can do

lostPercent = out.split('%')[0].split('(')[1]

edited Feb 21, 2012 at 15:50

answered Feb 21, 2012 at 14:04

Niek de Klein

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Comments

Eli Courtwright · Accepted Answer · 2012-02-21 14:04:14Z

0

import re
lost = int(re.findall(r"Lost = (\d+)", out)[0])

This applies a regular expression to capture the number that comes after "Lost =" and converts it to an integer.

answered Feb 21, 2012 at 14:04

Eli Courtwright

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