How do I increase the scrollback buffer size in tmux?
If I enter copy mode, the number of available scrollback lines is always below 2000.
The history limit is a pane attribute that is fixed at the time of pane creation and cannot be changed for existing panes. The value is taken from the history-limit session option (the default value is 2000).
To create a pane with a different value you will need to set the appropriate history-limit option before creating the pane.
To establish a different default, you can put a line like the following in your .tmux.conf file:
set-option -g history-limit 3000
Note: Be careful setting a very large default value, it can easily consume lots of RAM if you create many panes.
For a new pane (or the initial pane in a new window) in an existing session, you can set that session’s history-limit. You might use a command like this (from a shell):
tmux set-option history-limit 5000 \; new-window
For (the initial pane of the initial window in) a new session you will need to set the “global” history-limit before creating the session:
tmux set-option -g history-limit 5000 \; new-session
Note: If you do not re-set the history-limit value, then the new value will be also used for other panes/windows/sessions created in the future; there is currently no direct way to create a single new pane/window/session with its own specific limit without (at least temporarily) changing history-limit (though show-option (especially in 1.7 and later) can help with retrieving the current value so that you restore it later).