grep

grep [options] PATTERN [FILE...]
grep [options] [-e PATTERN | -f FILE] [FILE...]

In basic regular expressions the metacharacters 
  ? , + , { , | , ( , and  )
lose their special meaning; instead use the backslashed versions:
 \? ,\+ ,\{ ,\| ,\( , and \)

• -v (invert-match)
• -c (count)
• -m (max-count)
• -n (line-number)
• -L (files-without-match)
• -l (files-with-matches)

• --include=PATTERN
• --exclude=PATTERN

• -q(quiet)
• -s(no-messages)
• > /dev/null

• -A(after)
• -B(before)
• -C(context)

• --binary-files=TYPE

TYPE:

• binary(default)
• without-match(-I)
• text(-a)

• --color

GREP_COLOR

• never
• auto
• always

• -G(basic-regexp, default)
• -E(extended-regexp)
• -P(perl-regexp)
• -F(fixed-strings)

grep -F -e "one" -e "two" file

grep -F 'one
two' file

• -f(file)

• -b(byte-offset)
• -u(unix-byte-offsets)