# FILE:     grep.py
# AUTHOR:   Eugene Wallingford
# DATE:     2014/10/16
# COMMENT:  Search for occurrences of a string in a file.  Match
#           strings regardless of upper- or lowercase.

search_str = input('grep: ').lower()    # Make the search string lowercase.
filename   = input('in  : ')

textfile   = open(filename, 'r')
line_num = 0

for line in textfile:
    line_str  = line.strip()
    line_num += 1

    # Search for string in a lowercase version of the line...
    if line_str.lower().find(search_str) >= 0:
        # ... but print the original version of the line.
        print(line_num, line_str)

textfile.close()