Question

I have the following expect script to:

• SSH to host
• accept password from user if required
• Once ssh successful (prompt appears), set an environment variable
• Once back at prompt again, run a program for network testing
• Once back at prompt again, exit expect and close ssh session

#!/usr/bin/expect
set hostname [lindex $argv 0]
set working_dir [lindex $argv 1]
set package [lindex $argv 2]
set tcl_test $working_dir/$package.tcl
set config $working_dir/$package.config
set logdir $working_dir/$package
set timeout 30
set prompt "\~\\\]\\\$"

eval spawn ssh $hostname
expect {
    -re "(yes/no)" {send "yes\r"}
    -re "password\:" {      
        interact {
            -o
            -re $prompt {send "export VARIABLE1=$working_dir\"\r"}
            -re $prompt {send "issue-test-command -config $config -module $tcl_test\r"}
        }
    }
}

The password match and interact works correctly. As soon as $prompt is matched, the environment variable export command is issued:

-re $prompt {send "export VARIABLE1=$working_dir\"\r"}

This is correct, but then rather than moving on to the line:

-re $prompt {send "issue-test-command -config $config -module $tcl_test\r"}

The same line is read, the pattern is matched again and the same command is performed. This results in a permanent loop of issuing the same command.

How can I force interact to move on to the next line, or use a different expect built-in to achieve what I’m after?

Answer 1

Imagine you’re giving instructions to someone:

1. if you see a red light then stop
2. if you see a red light then go

You wouldn’t be surprised if they get confused. That’s what you’re doing to Expect with multiple -re $prompt branches. However Expect just takes the first instruction you tell it.

Try this:

    interact {
        -o
        -re $prompt {
            send "export VARIABLE1=\"$working_dir\"\r"
            send "issue-test-command -config $config -module $tcl_test\r"
        }
    }

BTW:

1. you’re missing exp_continue after send "yes\r"
2. you’re sending the wrong number of double quotes on the export command