I need to copy files via scp from a zsh script.  Say, $1 holds a file name
containing ':'.  When I do

scp $1 $host:$dir

I get an error from scp, treating the prefix of $1 before : as a source host
name.  What's the right way to quote it -- '$1' would preclude interpolation
of $1, which is exactly why $1 is used in the first place..

Cheers,
Alexy.