How do I increase the scrollback buffer size in tmux?

Question

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.

Answer 1

Plus the answers above; for the "current window buffer" you can increase buffer-limit using command:

tmux set-option buffer-limit 3000

because in document you will see:

history-limit [lines]: Set the maximum number of lines held in window history. This setting applies only to new windows - existing window histories are not resized and retain the limit at the point they were created.

buffer-limit [number]: Set the number of buffers; as new buffers are added to the top of the stack, old ones are removed from the bottom if necessary to maintain this maximum length.

For me I prefer to use buffer-limit only for tmux-sessions that I really need history checkups and this helps to manage multiple jobs with limited resources and prevent unpredicted memory loss.

Answer 2

I'm adding this answer because it isn't generally a good idea to just create a new configuration file and put your new configuration inside it, without first checking to see if there is an existing configuration file.

• This is a good piece of general advice across Linux, it isn't specific to tmux

The reason for this is if you create a new configuration file, it is likely that this will clobber any configuration being loaded from files elsewhere in your system.

• First check to see if you can find any files which look relevant:
• find / -type f -name '*tmux.conf*' 2>/dev/null
• This runs a find command in the root directory of your filesystem to find any files with a regex matching *tmux.conf*
• 2>/dev/null ensures any Permission denied errors are discarded to avoid cluttering the output

On my system, it doesn't look like there is any existing configuration. But I do have this:

/usr/share/doc/tmux/example_tmux.conf

If we inspect the contents we can see it has some potentially useful presets.

However, since I don't appear to have a default configuration file being loaded from somewhere else in the system, it would seem ok for me to go ahead and create ~/.tmux.conf.

To give an example of a case where this is important (at least in my experience, on most systems) consider the case of vim.

$ find / -type f -name '*vimrc*' 2>/dev/null
/usr/share/vim/vim90/gvimrc_example.vim
/usr/share/vim/vim90/vimrc_example.vim
/etc/vim/vimrc
/etc/vim/vimrc.tiny
/home/me/.vimrc

Again, on this system there isn't a huge amount of stuff returned, however we do have /etc/vim/vimrc.

To create the file /home/me/.vimrc I copied the file /etc/vim/vimrc. This avoids losing any sensible default configuration which is preconfigured there.

If you were to just create ~/.vimrc, when vim loads, it will check for this file with higher priority than checking for general system-wide configuration files such as /etc/vim/vimrc.

That means, it won't read /etc/vim/vimrc.

If you have ever created a configuration file from scratch for tumx, vim, or any other program and wondered why the behavior changed in strange ways, this might be why.

Answer 3

As the scrollback buffer size (i.e., history-limit) can't be re-set for existing panes, the workaround that worked for me thus far is using the pipe-pane command (which is similar to screen's log command).

Quoting this Unix & Linux answer:

You can use the pipe-pane command after the tmux prefix (with the default prefix, this would be CTRL+b:pipe-pane).

Example 1

The example found here will overwrite the target file (in this case, myfile):

pipe-pane "cat >myfile"

Example 2

The example in the tmux manual will bind a key combo to toggle logging and to append to the specified file instead of overwriting it:

The -o option only opens a new pipe if no previous pipe exists, allowing a pipe to be toggled with a single key, for example:

bind-key C-p pipe-pane -o 'cat >>~/output.#I-#P'

Answer 4

This will fix it in one liner:

echo "set -g history-limit 5000" >> ~/.tmux.conf

For those of you that don't know where to find .tmux.conf file, you can simply create a new file at ~/.tmux.conf, then add this single line into the file set-option -g history-limit 50000 if above command will throw error. (comment taken from @C.Lee on this answer)

Answer 5

This builds on ntc2 and Chris Johnsen's answer. I am using this whenever I want to create a new session with a custom history-limit. I wanted a way to create sessions with limited scrollback without permanently changing my history-limit for future sessions.

tmux set-option -g history-limit 100 \; new-session -s mysessionname \; set-option -g history-limit 2000

This works whether or not there are existing sessions. After setting history-limit for the new session it resets it back to the default which for me is 2000.

I created an executable bash script that makes this a little more useful. The 1st parameter passed to the script sets the history-limit for the new session and the 2nd parameter sets its session name:

#!/bin/bash
tmux set-option -g history-limit "${1}" \; new-session -s "${2}" \; set-option -g history-limit 2000

Answer 6

Open tmux configuration file with the following command:

vim ~/.tmux.conf

In the configuration file add the following line:

set -g history-limit 5000

Log out and log in again, start a new tmux windows and your limit is 5000 now.

Answer 7

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).