Hey there! I see you want to automate responses to known prompts in your bash script using Expect, while letting users handle unexpected questions manually. That's a common use case, and here's a straightforward solution:

Step 1: Create the Expect Script #

Let's build an Expect script (name it auto_reply.exp) that monitors your script.sh output, auto-replies to predefined questions, and hands off control to the user for unrecognized prompts.

#!/usr/bin/expect -f

# Launch your bash script
spawn ./script.sh

# Disable timeout so Expect waits indefinitely for prompts
set timeout -1

# Loop to handle all prompts until the script exits
while {1} {
    expect {
        # Auto-reply to your known questions
        "Would you like tea ?" {
            send "Yes, please!\r"
            exp_continue  # Keep listening for next prompts
        }
        "Would you like car ?" {
            send "No, thanks!\r"
            exp_continue
        }
        # Catch unknown prompts (matches any line ending with a question mark)
        -re {.*\?} {
            # Print the unexpected prompt for the user
            puts "\nUnexpected prompt: [expect_out(buffer)]"
            puts "Please enter your response manually:"
            
            # Switch to manual input mode (disable terminal echo temporarily)
            stty raw -echo
            gets stdin user_response
            stty -raw echo
            
            # Send the user's input to the bash script
            send "$user_response\r"
            exp_continue
        }
        # Exit the script when the bash process finishes
        eof {
            exit 0
        }
    }
}

Step 2: Breakdown of Key Parts #

• Shebang: #!/usr/bin/expect -f tells the system to run this script with the Expect interpreter.
• Spawn: spawn ./script.sh launches your target bash script and lets Expect monitor its output.
• Timeout: set timeout -1 ensures Expect never times out waiting for a prompt (critical for interactive flows).
• Auto-Reply Blocks: For each known question, we send a predefined response and use exp_continue to keep monitoring for the next prompt.
• Manual Fallback: The regex -re {.*\?} catches any unrecognized prompt ending with a question mark. We then pause automation, let the user type a response, and send it to the bash script.
• EOF Handling: When your script.sh finishes running, Expect detects the end-of-file signal and exits cleanly.

Step 3: Run the Script #

1. Give your bash script execute permissions:

   chmod +x script.sh
   

2. Do the same for the Expect script:

   chmod +x auto_reply.exp
   

3. Launch the automation:

   ./auto_reply.exp
   

Test It Out #

When you run the script:

• It will auto-reply to "Would you like tea ?" and "Would you like car ?"
• When it hits "Would you like cup ?" or "Would you like cake ?", it will prompt you to type a manual response, then continue the flow.

内容的提问来源于stack exchange，提问作者Logicsystem360