How to use ssh tail command and write to local file

Question

I'm trying to write a script that reads logs from 3 linux machines and writes the logs (with some kind of prefix) in one file.

My problem is that I can access to the file in order to see it, but when I try to write it doesn't work.

Working code

expect -c "
spawn ssh user@x.x.x.x \" tail -f my_file\"
expect { 
   \"*assword\" {send \"PASS\r\";}
}
expect eof 
"

if I add

tail -f >> my_file.log

it doesn't work.

Answer 1

First off, I would highly recommend learning how to use SSH with keys so that you don't need a password.

Then, all you need to do is this:

ssh username@server 'tail -f filename' >> my_file.log

Answer 2

Your command

tail -f filename >> my_file.log

is being run on the remote. So my_file.log is on the remote. To get the output to a local file, move the >> my_file.log to the end of the expect script:

 expect -c "..." >> my_file.log