search files for string patterns

EXAMPLES
	grep "pattern" file.txt
		print lines of file.txt that contain a string matching the "pattern"
	grep -c "pattern" file.txt
		like above, but instead of printing actual matches it prints the number of matches found
	grep -rin "pattern" .
		search recursively and case-insensitively for "pattern" in all files in . and below, print all lines that contain a match with line numbers
	grep -rinv "pattern" .
		like above, but instead invert the matching
	
FLAGS
	-r	go recursively through all subdirectories
	-i	ignore case in the search pattern
	-o	print only the matching string, not the entire line containing a match
	-v	invert matching (print non-matches instead of matches)
	-n	add line numbers to printed matches
	-c	output the number of matches instead of actual matches
	-A	print matches with Ai lines of context above
	-B	print matches with Bi lines of context below
	-C	print matches with Ci lines of context above and below
	-E	interpret the search pattern as a full-fledged regexp (e.g. regexp operators like () don't ned to be escaped)
	-F	interpret the search pattern as a plain string
