Variable substitution (stupid noob) question in tcsh
I have a bunch of files whose names are of the format runXon, where X is a number between 1 and 4. I would like to write a script that refers to one of these sets at a time, so that I can set a variable RunNumber and do this :
set allfiles = `ls run$RunNumberon`
However, the shell very reasonably complains that RunNumberon is not defined. How can I tell it that the variable name ends before 'on'? I'm sure this is pretty trivial, but I can't find it in my manual.