from `man grep`: -A NUM, --after-context=NUM Print NUM lines of trailing context...

from `man grep`:
     -A NUM, --after-context=NUM
            Print  NUM  lines  of  trailing context after matching lines.  Places a
            line containing a group separator (--)  between  contiguous  groups  of
            matches.  With the -o or --only-matching option, this has no effect and
            a warning is given.

     -B NUM, --before-context=NUM
            Print NUM lines of leading context before  matching  lines.   Places  a
            line  containing  a  group  separator (--) between contiguous groups of
            matches.  With the -o or --only-matching option, this has no effect and
            a warning is given.

     -C NUM, -NUM, --context=NUM
            Print  NUM  lines  of output context.  Places a line containing a group
            separator (--) between contiguous groups of matches.  With  the  -o  or
            --only-matching option, this has no effect and a warning is given.