It turns out that when tmux was launched with the TERM set to xterm, it
was causing tmux colors to go out of whack. This imports the original
setting from my previous environment which sets the tmux alias to launch
with the TERM set to screen-256color-bce
When executing commands over SSH, such as SCP, the server (tput)
complains that there is no terminal defined. This fix sets the T_*
variables only if the TERM variable is not empty.
Add a function add_to_path so that it can prepend any specified path
to the PATH environment variable, but only if it is not already there.
Don't worry about (re)setting the LS_COLORS environment if it's already
been set by the system bashrc.