Python Search String One Liner

Question

I'm trying to use Python a little more and I know this isn't the best use case for it but it's bothering me on why I can't get it to work.

I'm currently using Python 2.7.6 and I want to cat a file and then pull specific strings out of it based on regex. The below code works fine for what I want, but only looks at the first line.

cat /tmp/blah.txt | python -c "import re,sys; m = re.search('Host: (\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}).*OS:(.*) Seq:', sys.stdin.read()); print m.group(1), m.group(2)"

So I assumed I could just use a for loop or fileinput to read the entire file and then put the rest of my code in there but I keep on getting errors with the for loop.

cat /tmp/blah.txt | python -c "import sys; for line in sys.stdin: print line"                                                                                                        File "<string>", line 1
    import sys; for line in sys.stdin: print line
                 ^
SyntaxError: invalid syntax

I've tried a few variations of this but can't get it to work. It always says invalid syntax at the for portion. I know it has to be something very stupid/obvious I'm doing but any help would be appreciated.

If I created a program called arg.py and put the code below in it and call Python via cat, it works fine. It's just the one liner portion that isn't working.

import sys
for line in sys.stdin:
    print line

Why are you mixing Python and the command line like that? Just use `grep`, or open the file from Python. — jonrsharpe, Nov 18 '16 at 21:43
As I stated in my first sentence, I know this is not the best use case for it, I just wanted to see if I could get it to work. I do a lot of stuff via command line for searching logs and wanted to see if I could make it work for Python as well. — Eric, Nov 18 '16 at 22:16

score 2 · Accepted Answer · edited May 23 '17 at 10:32

2

Unfortunately, constructs that introduce indentation in python like if, for among others are not allowed to be preceded by other statements.

Even in your arg.py file try the following:

import sys; for line in sys.stdin: print line

You will discover that the syntax is also invalid which results to the same error.

So, to answer your question, your problem is not the fact that you ran the program in the terminal but the problem is in python syntax itself. It does not support such syntax Check out a related question

edited May 23 '17 at 10:32

Community

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answered Nov 18 '16 at 22:09

Ken4scholars

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Thanks for the information Ken. I saw other one liners that used for statements so just assumed it work overall. I didn't think anything about it being preceded by other statements. – Eric Nov 18 '16 at 22:17
@Eric I'm glad I was of help. Please don't forget to up-vote the answer and mark as solution if you're satisfied with it – Ken4scholars Nov 18 '16 at 23:13

Python Search String One Liner

1 Answers1