Can't Close a Scpi(Telnet) Session with Echo "^]" When I Use It in a Script

Auto exit Telnet command back to prompt without human intervention ^] quit close exit code 1

A slight improvement to the answer provided by Matthew above which allows you to use it inside shell scripts:

$ echo -e '\x1dclose\x0d' | telnet google.com 80
Connected to google.com.
Escape character is '^]'.

telnet> close
Connection closed.
$ echo $?
0

Automating telnet session using bash scripts

Write an expect script.

Here is an example:

#!/usr/bin/expect

#If it all goes pear shaped the script will timeout after 20 seconds.
set timeout 20
#First argument is assigned to the variable name
set name [lindex $argv 0]
#Second argument is assigned to the variable user
set user [lindex $argv 1]
#Third argument is assigned to the variable password
set password [lindex $argv 2]
#This spawns the telnet program and connects it to the variable name
spawn telnet $name 
#The script expects login
expect "login:" 
#The script sends the user variable
send "$user "
#The script expects Password
expect "Password:"
#The script sends the password variable
send "$password "
#This hands control of the keyboard over to you (Nice expect feature!)
interact

To run:

./myscript.expect name user password

how do I sent escape character ^] through a spawned telnet session?

You send the ESC control sequence. Try send "\x1b\r"

can we exit without error from telnet with MozRepl?

You need to send ^] character, that is an unprintable group separator character before your telnet client terminates your connection after executing all commands you gave it via pipe. Most versions of echo program can produce unprintable characters using -e option. Group separator is 035 in octal (you can see the entire ASCII table with man 7 ascii on *nix systems.). So, the entire command should look like this:

$ (echo "content.location.href = 'http://v4.ident.me/'"; sleep 2; echo -e '\035'; sleep 2) | telnet localhost 4242 > /dev/null
$ echo $?
$ 0

Linux script to parse telnet message and exit

You could use internal TCP mechanism:

#!/bin/bash

exec 3<>/dev/tcp/127.0.0.1/80
# echo -en "eventualy send something to the server\n" >&3
RESPONSE="`cat <&3`"
echo "Response is: $RESPONSE"

Or you could use nc (netcat), but please don't use telnet!

How to connect to a phoneix framework app locally by telnet?

Phoenix uses Cowboy as underlying webserver. It has different timeout options, but the one we need is request_timeout.

It defaults to 5_000 (in milliseconds) and can be changed inside configuration like this:

config :my_app, MyApp.Endpoint,
  http: [
    port: ...,
    ...
    protocol_options: [
      request_timeout: 60000 # minute here - for example
    ]
  ]

Now, you have a minute to type your:

GET /

inside telnet CLI

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