Grep and Python

Question

I need a way of searching a file using grep via a regular expression from the Unix command line. For example when I type in the command line:

python pythonfi         


        

Answer 1

Concise and memory efficient:

#!/usr/bin/env python
# file: grep.py
import re, sys

map(sys.stdout.write,(l for l in sys.stdin if re.search(sys.argv[1],l)))

It works like egrep (without too much error handling), e.g.:

cat input-file | grep.py "RE"

And here is the one-liner:

cat input-file | python -c "import re,sys;map(sys.stdout.write,(l for l in sys.stdin if re.search(sys.argv[1],l)))" "RE"