csh alias with variable number of arguments

Question

I would like to create a csh alias that performs one operation if invoked without arguments and a second operation if invoked with a single argument. Does anyone know how to do

Answer 1

Aliases in tcsh are limited; for more advanced things, I've found that the best way is to source a (t)csh script, like so:

alias my-cmd 'source ~/.tcsh/my-cmd.tcsh'

And ~/.tcsh/my-cmd.tcsh would contain something like:

if ( $1 != '' ) then
        echo "we have an argument: $1"
else
        echo "we don't have an argument"
endif

Example output:

% my-cmd
we don't have an argument
% my-cmd hello
we have an argument: hello

Now, it may also be possible to do this with just an alias, but this will be much more maintainable & cleaner in the long run, IMHO.

(I've assumed tcsh here since almost all, or perhaps even all, c shells are tcsh these days).