How can I create a client spec from older revision of a template?

I can create a perforce client spec from a template with:

% p4 client -t template_spec

Is it possible to tell p4 client to use a previous revision of the template client?

I wrongly assumed one of those commands would work:

% p4 client -t template_spec#4
% p4 client -t template_spec@2019/05/01

I get the error "Revision chars (@, #) not allowed in 'template_spec@2019/05/01'.

I also considered having p4 client to describe the content but this one does not work either:

% p4 client -o template_spec@2019/05/01

But I get same error as above.

I'm looking for a solution using the command line only, not involving p4v.

Thank you.

With streams (which are essentially the modern version of template clients) you can do this via the StreamAtChange field, which causes your client view to be based on the version of a stream as of a given changelist number.

With classic clients, you'll need to use a spec depot and do something like:

p4 print -q //spec/template_spec#4 | sed -e "s/template_spec/new_client/" | p4 client -i