Clever Geek Handbook

Wait for prompts pending script

I need the expect

script to wait for the issued command to complete and then exit telnet

. Here is the script:

spawn telnet host
send "username\r"
send "password\r"
sleep 3
send "custom_command\r"
while {???}
{
    sleep 1
}
send "logout\r"
expect eof

Part I don't know as a phrase ???

. I just need to wait for it to appear prompt

and as soon as it appears the script should end. I guess it should be something like [gets line != "prompt>" ]

.

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3 answers


expect

the team expect to be appropriate here. Something like expect "prompt\n"

, followed by sending the output file.



As a side note, if this is a regular telnet system, you usually have to wait to receive a prompt for a username and password before simply submitting it. See how to automate a telnet session while waiting or waiting for a script to automate telnet login

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You really have to expect something before submitting something to get the timing right. Something like:



exp_internal 1      ;# expect internal debugging. remove when not needed
spawn telnet host
expect "login: "
send "username\r"
expect "Password: "
send "password\r"
set prompt {\$ $}   ;# this is a regular expression to match the *end* of
                     # your shell prompt. Adjust as required.
expect -re $prompt
send "custom_command\r"
expect -re $prompt
send "logout\r"
expect eof
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I tried the command expect, but it didn't work, after some research, trial and error, I figured out the following:

  • Use expect "prompt>\r"

    insteadexpect "prompt>"

  • Curly curly braces must be on the same line as the wait command, for example expect "prompt>\r" {

  • Use set timeout -1

    to wait for a prompt indefinitely instead of 10 seconds

So the answer is:

spawn telnet host
send "username\r"
send "password\r"
sleep 3
set timeout -1
send "custom_command\r"
expect "prompt>\r" {
    send "logout\r"
    expect eof
}
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