Python: find string in file

Question

I have the following in my python script..

hostIP = sys.argv[1]
hostsFileLoc = "hosts.txt"

if not hostIP in open(hostsFileLoc).read():
    # Script to add if the string is not in file
else:
    # Print message

The only problem with this is that it is not an exact match, for example...

If my file contains:

192.168.0.111

And my hostIP is:

192.168.0.11

Then it will find it as a match. I thought I might be able to do this with regex, as there will always be a space ("\s+") or a comma ("\,") so I thought I could use something like

test = re.compile("^" + hostIP + "[\s\,]*")

and use test as my search, but this obviously does not work. I've tried to find some documentation on this but to no avail. Has anyone a suggestion on how I can use a variable with regex to have a more specific search.

Thanks

MHibbin

Maksym Polshcha · Accepted Answer · 2012-07-01 08:40:49Z

3

you can split your text file by delimiters (whitespace for example) and then find string in the list:

if not hostIP in open(hostsFileLoc).read().split():
    # Script to add if the string is not in file
else:
    # Print message

Put your delimiter into split() if you use other than whitespaces

answered Jul 1, 2012 at 8:40

Maksym Polshcha

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Comments

Lev Levitsky · Accepted Answer · 2012-07-01 08:38:28Z

3

The only reason it doesn't work is that you use * in "[\s\,]*", which means "space or comma zero or more times". Thus it will match against '192.168.0.111' because it has zero spaces after 11. Change * to + ("one or more times") and it should work.

answered Jul 1, 2012 at 8:38

Lev Levitsky

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1 Comment

MHibbin Over a year ago

Thanks, for some reason I thought "+" would mean that it would need at least one whitespace AND one comma... wasn't thinking correctly. However I have gone withe split method in the other answer as that was posted first and it worked for my needs. I will bare this in mind though, thanks for the response.

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