Bash, Expect : Execution of command after SSH is not working - bash

Question

I need to login to a VM and execute some command there. I have gone through all question related to the same topic but did not find any solution with EXPECT. I am using EXPECT as I need to pass the password while using SSH.
I am getting "command not found error" while executing my script but manually, it is working fine.
#!/usr/bin/expect -f
set user [lindex $argv 0]
set to [lindex $argv 1]
set pass [lindex $argv 2]
set command [lindex $argv 3]
puts "$user, $to , $command and $pass ."
# connect via scp
spawn sudo ssh -t -t -v $user#$to << EOF
ls
EOF
#######################
expect {
-re ".*es.*o.*" {
exp_send "yes\r"
exp_continue
}
-re ".*sword.*" {
exp_send $pass\n
}
}
interact
Error received :
spawn sudo ssh -t -t -v username#server_ip << EOF
Invalid command name "ls"
while executing "ls"
(file "./establishSSHConnection.sh" line 10)

Answer 1

It looks like you are trying to send commands to the remote system in a 'here' doc:
spawn sudo ssh -t -t -v $user#$to << EOF
ls
EOF
Instead, you should use 'exp_send' to send the ls command just before 'interact' i.e., remove the 'here' doc:
spawn sudo ssh -t -t -v $user#$to
And put the ls command here at the end:
expect {
-re ".*es.*o.*" {
exp_send "yes\r"
exp_continue
}
-re ".*sword.*" {
exp_send "$pass\r"
}
}
exp_send "ls\r"
interact
EDIT:
Ah, I misunderstood. If you just want to run the command then you'll need to tell the other end to close the connection:
expect {
-re ".*es.*o.*" {
exp_send "yes\r"
exp_continue
}
-re ".*sword.*" {
exp_send "$pass\r"
}
}
exp_send "ls\r"
exp_send "exit\r"
expect {
eof {puts "Connection closed"}
timeout {puts "Connection timed out"}
}

Answer 2

Expect (being built atop Tcl) does not have here documents.
If you want to execute the command remotely and then end the ssh session, do
set command "ls -lrt" ; # for example
spawn sudo ssh -t -t -v $user#$to $command
# ... log in logic
expect eof