Everything you need to know about tmux – Panes

A tmux pane is the entity that we actually use to run commands, scripts, and processes, such as ssh, backup, vim, htop, and what have you. Technically, they are pseudoterminals  encapsulating shells, like Zsh or Bash. In other words, they are terminals within a terminal. Panes are used to allow the user to organize their workflow by splitting the tmux window into vertical and horizontal panes, each running a process or a program. The layout of the panes are managed by the tmux window they reside in. By default, when tmux server is initialized, a session is started. Within this session a single window is created. This window will contain one pane, by default.

Servers hold one or more Sessions. A Session holds one or more Windows. A Window holds one or more Panes. 

Panes are created by splitting the window they reside in. Splitting can be performed vertically or horizontally using tmux shortcuts or using tmux commands (good when scripting). On an average, a tmux window can have several panes open. The terminal dimension is the limiting factor on how many panes you can split further.

Prefix = Ctrl + b (default) 

When using Prefix + w , tmux will display the list of windows and their associated panes. In the example below, we see that there is 1 window in the current session 0. The window has a name of “1” and it contains 2 panes. The active pane in window 1 is the pane with name “bash”. By default, tmux assigns the name of the running process as the pane’s name.

When the last pane in a window is closed, the tmux window will be terminated by tmux.

To create a new pane by splitting the window vertically with 75% height

tmux split-window -p 75

You can experiment withe split-window command by using -v and -h switches (vertical and horizontal respectively). The -p switch signifies the percentage.

Common tmux Shortcuts for Panes 

Prefix = Ctrl + b (default) 

Zooming/Unzooming

There are times when you want to work on a process or a program inside one pane and you need to enlarge it to take the entire terminal space. This can be accomplished by using the shortcut:

Prefix + z

You can press the same shortcut to unzoom and return the pane to its previous state. If you like to create a custom key binding, you can follow the example below and enter it in your ~/.tmux.conf. This will bind Ctrl+y to zoom in and out.

bind -n C-y resize-pane -Z

Advanced Tip!

You can navigate the tmux panes in a vim-like style, using the letters (h j k l). To accomplish this, bind these keys in your ~/.tmux.conf file, as follows:

bind h select-pane -L 
bind j select-pane -D 
bind k select-pane -U 
bind l select-pane -R