Jim Meyering wrote:
I too find this behavior surprising:
$ seq 3|grep -F xxx$'\n'
1
2
3
This feels like a bug, since it's an artifact of how grep accumulates
multiple keys internally: it uses newline as the separator
(http://git.savannah.gnu.org/cgit/grep.git/tree/src/grep.c#n2308).
Including a literal newline in the search string conflicts with that.
It's not an artifact; it's intended behavior. POSIX says that xxx$'\n' (which
expands to three 'x's followed by a newline) is a pattern_list, not a pattern.
A pattern_list is defined to be a series of patterns separated by newlines (not
terminated by newlines), so that pattern_list has two patterns, xxx and the
empty pattern.
