Possible to remove the need to add a line in .bashrc?

[arl]

The best way to do this, is to make tmux-gitbar.sh a script called, with absolute path, from PROMPT_COMMAND, instead of, as I'm doing now, defining PROMPT_COMMAND as:

PROMPT_COMMAND="update_gitbar; $PROMPT_COMMAND"

So:

PROMPT_COMMAND="/full/path/to/tmux-gitbar.sh; $PROMPT_COMMAND"