How to pass argument in Expect through the command line in a shell script

If you want to read from arguments, you can achieve this simply by

set username [lindex $argv 0];
set password [lindex $argv 1];

And print it

send_user "$username $password"

That script will print

$ ./test.exp user1 pass1
user1 pass1

You can use Debug mode

$ ./test.exp -d user1 pass1