bug#63819: Gnu `grep '.*'` does not match an empty string.

[Paul Eggert]

On 2023-05-31 10:18, Bob Vincent Il (US) via Bug reports for GNU grep wrote:

I discovered only today that the following commands all behave identically:

   *   grep -q '.*'
   *   grep -q '.\+'
   *   grep -q .
   *   grep -qE '.*'
   *   grep -qE '.+'
   *   grep -qE .

No they don't. For example:

$ echo '' | grep -q . ; echo $?
1
$ echo '' | grep -q '.*' ; echo $?
0