pub fn login_command(shell: &Path, args: &[String]) -> ShellCommandExpand description
The program and arguments that start shell with args as a login
shell, as Ghostty does.
On macOS that is login(1), so getlogin, SHELL and the rest of a
login behave as a user expects there: /usr/bin/login -flp <user> /bin/bash --noprofile --norc -c "exec -l <shell> <args>", with -q
when ~/.hushlogin exists. -p keeps the environment, so shell
integration still reaches the shell. Elsewhere, and on macOS when the
user is unknown, it is the shell with -l first. Windows has no login
shell, so there it is the shell and args as they are.