Android experiences

grep

-i, –ignore-case
Ignore case distinctions in both the PATTERN and the input files. (-i is specified by POSIX.)

-R, -r, –recursive
Read all files under each directory, recursively; this is equivalent to the -d recurse option.

-v, –invert-match
Invert the sense of matching, to select non-matching lines. (-v is specified by POSIX.)

-w, –word-regexp
Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore.