Tmux environment variables

The user configuration file for the tmux terminal multiplexer, .tmux.conf, supports defining and using environment variables in the configuration, with the same syntax as most shell script languages:

TERM=screen-256color
set-option -g default-terminal $TERM

This can be useful for any case in which it may be desirable to customise the shell environment when inside tmux, beyond setting variables like default-terminal. However, if you repeat yourself in places in your configuration file, it can also be handy to use them as named constants. An example could be establishing colour schemes:

TMUX_COLOUR_BORDER="colour237"
TMUX_COLOUR_ACTIVE="colour231"
TMUX_COLOUR_INACTIVE="colour16"

set-window-option -g window-status-activity-bg $TMUX_COLOUR_BORDER
set-window-option -g window-status-activity-fg $TMUX_COLOUR_ACTIVE
set-window-option -g window-status-current-format "#[fg=$TMUX_COLOUR_ACTIVE]#I:#W#F"
set-window-option -g window-status-format "#[fg=$TMUX_COLOUR_INACTIVE]#I:#W#F"

The explicit commands to work with environment variables in .tmux.conf are update-environment, set-environment, and show-environment, and are featured in the manual.

One thought on “Tmux environment variables

  1. Pingback: Using tmux environment variables « 0ddn1x: tricks with *nix

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