New which() options -q (quiet) and -1 (one)
New which() options -q (quiet) and -1 (one)

-q (quiet): Suppress warnings (as opposed to all output with -s).

-1 (one): Output the results for at most one of the arguments in
   descending order of preference: once a search succeeds, ignore
   the rest. Implies -q.
   This is useful for finding a command that can exist under
   several names, for example:
        harden as gnutar -p $(which -1 gnutar gtar tar)
   This option modifies which's exit status behaviour: 'which -1'
   returns successfully if any match was found.

Also new: use insubshell() to issue a warning if 'which -s' (silent/no
output) is used in a subshell, such as a command substution.

modernish/modernish