grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus (-) is given as file name) for lines containing a match to the given PATTERN. By default, grep prints the matching lines. commandline session $ cat first.txt name-jeffrin Age-35 Sex-Male $ grep 3. first.txt Age-35 $ grep A. first.txt Age-35 $ grep A first.txt Age-35 $ grep . first.txt name-jeffrin Age-35 Sex-Male $ grep x.M first.txt Sex-Male $ grep n. first.txt name-jeffrin $ grep 5. first.txt $ grep 5. first.txt $