TMUX - copy mode and how to control multiple servers at once

Two tips which needs to be documented:

The first one is how to copy in tmux, which had me struggling a lot. Most places say that you need to type the following sequence:
CTRL+a,[ (note my prefix is CTRL+a instead if CTRL+b).
Then something tricky happens:
In some servers I found out that selection of text is initiated with either SPACE or CTRL+SPACE. So, try one of them.
Navigate with the ARROWS to select the text.
Than, copy the selected text with CTRL+W (or ALT+W if that does not work).
Now, navigate to the desired place where you want to paste the text and type the following sequence:
CTRL+a,].


The second tip is how to control multiple servers with TMUX:
First, export a variable called HOSTS holding your servers list, e.g.:

HOSTS="host1 host2 host3 host4 host5"

then run the following script in your BASH:

#!/bin/bash
# ssh-everywhere.sh

# a script to ssh multiple servers over multiple tmux panes 

usage() {
    echo
    echo
    echo "Application Call: "
    echo
    echo "$BNAME sessionname"
    echo "before calling the script do: export HOSTS='host1 host2 host3'"
    echo "as a list of hosts to work on, or you will be promted to type"
    echo "the list in." 
}

starttmux() {
    echo 
    echo $HOSTS
    if [ -z "$HOSTS" ]; then
       echo -n "Please provide of list of hosts separated by spaces [ENTER]: "
       read HOSTS
    fi
    
    tmux new-session -d -s $sessionname 
    for i in $HOSTS
    do
    tmux split-window -v -t $sessionname "ssh $i"
    tmux select-layout tiled
    done
    #tmux set-window-option synchronize-panes on
    tmux attach -t $sessionname 
}

BNAME=`basename $0`
if  [ $# -lt 1 ]; then
    usage
    exit 0
fi

sessionname=$1
starttmux

That is all about TMUX for now.

P.S.
After a long struggle again, I found out how to copy paste in VI mode with tmux:
SPACE, stars selection.
CTRL+m copies to buffer.
CTRL+a,] pastes the buffer.