While playing with grep, I was suprised by grep '*\.c' not giving an error (* is missing an operand). Arguably * applied to empty can match empty, but surprisingly enough, Acme's edit behaves differently. And even grep is not consistent (grep '*' is different than grep '' whereas both should be an empty pattern or the first one should be an error). Another funny one is that Edit gives back an error complaining of missing operand to * when the regexp is empty.
Greps from other systems accept an empty pattern (and are thus consistent but they would not have catched the error starting all this). cpu% echo hola | grep '*a' hola cpu% echo hola | grep '*' grep: *: syntax error cpu% echo hola | grep '' grep: empty pattern Edit , s/*// regexp: missing operand for * Edit: bad regexp in s command Edit , s/*c// regexp: missing operand for * Edit: bad regexp in s command Edit , s/// regexp: missing operand for * Edit: bad regexp in s command G.
