zsh の = (which的な意味で)
$ ls =ls /bin/ls*
どうみても ls `which ls`より使いやすいです今まで本当にありがとうございました (which へのメッセージ的意味で)。
If a word begins with an unquoted `=' and the EQUALS option is set, the remainder of the word is taken as the name of a command. If a command exists by that name, the word is replaced by the full pathname of the command.