TCL expect regular expression

Use this:

expect -re {[$#] }

The keys to this are: add the -re flag so that we can match an RE, and put the RE in {braces} so that it doesn't get substituted.

A more generic solution:

set prompt "(%|#|\\\$) $"
expect -re $prompt

This one matches %, # and $.
The second dollar sign ensures matching the pattern only at the end of input.