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
show-environment, and are
featured in the manual.