1. Tool for Automation and Testing
Expect
Tool for Automation and Testing

2. Expect - Introduction Unix automation and testing tool
Written by Don Libes
Primarily designed as an extension to the Tcl scripting language
Useable in interactive applications such as telnet, ftp, passwd, fsck, rlogin, tip, ssh, and others.

3. Expect – TCL* Basics Everything is a command No Fixed Parser
Case-Sensitive
Explicit Expression Evaluation
set a 5  a = 5
set b a+2  b = a+2
set c [expr $a+2]  c = 7 (Note: $ for variable substitution)
Simple variables are strings of arbitrary length
Real & Int  cast to real
Non-numeric string and real/int  cast to string
Built in Lists
Standard flow control structures (while, if, etc.)
String manipulation with Regular Expressions
Procedures – arguments can be passed by value or reference
*Tool Command Language

4. Expect – The Programming Language
Extension of TCL, so the syntax is TCL syntax
Basic command set
expect
send
spawn
Interact
Regular Expression pattern
matching
“Glue” to combine separate
executables

5. Expect – Pros / Cons Pros Cons
Built on existing system tools, so learning curve is small.
Extensive support from corporate entities* *Silicon Graphics, IBM, HP, Sun, Xerox, Amdahl, Tektronix, AT&T, ComputerVision and the World Bank
Numerous ports to other programming languages (Perl, Python, java, etc.)
Cons
Only useful for command line scripting
Cryptic syntax for those unfamiliar with TCL (When do I use a $ again?)
Generally machine dependent tools are run with Expect, so porting scripts cross-platform is not easily supported.

6. Expect – “Hello World!”
Start Expect with “expect” or write the script to a file and run > expect filename
send “Hello World!\n”
expect “Hi\n”
Putting it together
Expect “Hi\n”
{ send “Hi World!\n” }

7. Expect – More Advanced expect "hi\n" { send "Hi World!\n" } \
"hello\n" {send "Hello World!\n" } \
"bye\n" {send "Bye World!\n" }

8. Expect - Automation spawn ftp $argv
expect "Name" { send "anonymous\r" } \
"name" { send "anonymous\r" }
expect "assword:"
send
interact

9. Expect - Others
Brute Force security
Beer
Chess
Weather
Rogue
Hunt

10. Expect - GnuChess # start things rolling spawn gnuchess
set id1 $spawn_id
expect "White \\(1\\) :"
send "random\r"
send "depth 6\r"
send "go\r"
# read_first_move
expect -re "My move is : (.*)\n"
set id2 $spawn_id
send "depth 5\r"
send $expect_out(1,string)
while {1} {
expect {
-i $id2 -re "is : (.*)\n" {
send -i $id1 $expect_out(1,string) }
-i $id1 -re "is : (.*)\n" {
send -i $id2 $expect_out(1,string)

11. Expect - Questions