CODEWITHSUNDEEP
pythonsed
liv2hak
liv2hak

Reputation: 14990

passing a variable instead of input file to sed

I have a python program that calls sed as follows.

url = os.system("sed 's/.*proxy=\([^&]*\).*/\1/' message")

message is a variable containing some data.I think sed expects a file in that place. How is this usually done in python

Upvotes: 0

Views: 396

Answers (2)

lineinthesand
lineinthesand

Reputation: 247

E.g.

message = 'asdf proxy=127.0.0.1 fdsa'
re.sub('.+proxy=([^& ]*).*', r'\1', message)

yields

127.0.0.1

Be aware of greedy vs. non-greedy matching at the beginning of your regex.

Upvotes: 1

paxdiablo
paxdiablo

Reputation: 881623

Python comes with its own internal regex engine, which would be preferable, especially since the return code from os.system() is the exit code of the program rather than its standard output.

It also helps with portability since calling an external executable may not work on all systems (Windows has no sed by default).

For details, look into re.sub:

import re
url = 'http://xyzzy.com?paxdiablo=awesome'
url = re.sub(r'^[^?]*\?','',url)
url = re.sub(r'=',' is ',url);
print url

Or re.findall:

import re
url = 'http://xyzzy.com?Python=fantastic&paxdiablo=still%20awesome'
args = re.findall(r'[?&]([^?&]*=[^?&]*)', url)
for arg in args:
    (object,property) = arg.split("=")
    print object, "is", property.replace('%20',' ')

Or many of the other methods found in the re module for Python 2 or Python 3.

Upvotes: 5

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