expect script

#!/usr/bin/expect                                                                                                                                                                

set user "engineer"
set addr "router"
set pass "[lindex $argv 0]"

spawn sshpass -p "$pass" ssh -o UserKnownHostsFile= -o StrictHostKeyChecking=no "$user@$addr"

set timeout 20

expect {
    timeout {
        puts "Connection timed out"
        exit 1
    }

    "$user>" {
        send "help\r"
    }

    "$user>" {
        send "exit\r"
    }
}

What happens when the above script is run:

~# ./reboot-adsl-router SEEKRET
spawn sshpass -p SEEKRET ssh -o UserKnownHostsFile= -o StrictHostKeyChecking=no engineer@router
engineer>~# 

What happens for manual login from the command line:

~# sshpass -p SEEKRET ssh -o UserKnownHostsFile= -o StrictHostKeyChecking=no engineer@router

After entering the above command the terminal is cleared and the following starts from top of screen:

      |                 |           o             |              
      |---  ,---. ,---. |---. ,---. . ,---. ,---. |     ,---. ,---.
      |     |---' |     |   | |   | | |     |   | |     |   | |    
      `---' `---' `---' `   ' `   ' ` `---' `---' `---' `---' `    
                 N E X T   G E N E R A T I O N   G A T E W A Y
 --------------------------------------------------------------------
 NG GATEWAY SIGNATURE DRINK
 --------------------------------------------------------------------
  * 1 oz Vodka          Pour all ingredients into mixing
  * 1 oz Triple Sec     tin with ice, strain into glass.
  * 1 oz Orange juice
 --------------------------------------------------------------------

Product: vant-8_r16-2
Release: Jade (16.2)
Version: 16.2.7064-2201011-20170207212801-d592e891575d5fd3ba62668fd85dd2574bca7b1e


Hash config:         d592e891575d5fd3ba62668fd85dd2574bca7b1e
Hash openwrt:        246337582b1542cf5dbc0f9d2f19a0ea9500c4fc
Hash kernel:         d94a9b191cb4708f8b98dcb521298108ffd2f95a
Hash custo:          01381b6688b690ce9a54355ec085ba000c1c4a0d
Hash technicolor:    fe192c9f4ab79625ff4986c7a42da854ebf6dd4e
Hash lte:            546ac206f18443faf0e44720f4bfd28274f82851
Hash mindspeed:      91b6a7a4d703268d6023c3a58da3d33fc62e7ed8
Hash packages:       f07af7c7968e10e3e707d03d755aec232cffc6ec
====================================================================================
engineer>help
AVAILABLE COMMANDS:
===================
  add  (AddObject)
  apply
  count
  del  (delete,DeleteObject)
  dmesg
  dsldiagd
  get  (GetParameterValues,gpv,GPV)
  getpn  (GetParameterNames,gpn,GPN)
  ifconfig
  ifstatus
  ip
  iptables
  list
  logread
  nslookup
  ping
  ps
  readlogfile
  reboot
  resolve
  route
  rtfd
  set  (SetParameterValues,spv,SPV)
  stop
  subscribe
  tcpdump
  top
  traceroute
  ubuscall
  ubuslisten
  unsubscribe
  upgrade
  reload
  help
  exit
engineer>exit
Connection to router closed.
~#