Use cmd line arguments for expect script.

Below I have given a small example to get a file from ftp server. This code was written using expect.
Usage:- HOST PROMPT$ expect ftp_get_file.exp < IP > < user_name > < password > < file_to_get >

EX:-
#!/usr/bin/expect -f < IP >
set ip [lrange $argv 0 0]
set username [lrange $argv 1 1]
set password [lrange $argv 2 2]
set file [lrange $argv 3 3]
set timeout -1
#Spwan the Cfm1 Util stub
spawn ftp $ip
expect ":"
send -- "$username\r"
sleep 1
expect "Password:"
send -- "$password\r"
sleep 2
expect ">"
send -- "bi\r"
sleep 1
expect ">"
send -- "ha\r"
sleep 1
expect ">"
send -- "mget $file\r"
sleep 2
expect "?"
send -- "y\r"
sleep 1
expect ">"
send -- "by\r"
sleep 1
expect eof

NOTE:- If ur password contain any special character then use "\" in front of those characters.