Last time I talked about switching from screen to tmux.
However the default settings for tmux is that the command key is <CTRL> + b and thats not what you are used to from screen. There is a simple way of changing that by createing/editing you .tmux.conf file.
When tmux starts it reads the file .tmux.conf from you home directory.
To configure it to use <CTRL>+A for commad you add the folowing lines to it:
# remap prefix to Control + a
set -g prefix C-a
bind C-a send-prefix
The first line if a comment, and the second one (set -g prefix C-a) is the line that specify for tmux that <CTRL>+A is the commamd key.
The third line unset the Commad + B (CTRL + B 2 times) key that usually send a control b to the windows.
And the forth line binds Command +A to times to send a Ctrl A to the command running.
If you now starts tmux you have Ctrl + A as the command key.