Re: sharing environment between terminals.

[Ray Andrews <rayandrews@eastlink.ca>]

On 18/11/12 04:22 PM, Phil Pennock wrote:
> On 2012-11-17 at 16:39 -0800, Ray Andrews wrote:
>> Is there a way to instantly share environment variables between running
>> terminals?  I often have several open, and when I set an environment
>> variable in one, I'd like it to be available in all the others too.
>> 'export' doesn't help.
> If you use tmux to act as your terminal multiplexer / keepalive, then
> this seems to work.
>
> I just wrote it; this means there are probably bugs, beyond the known
> limitations.
Phil,

This is over my head, but I'll keep it and give it some study.
> Limitation: requires tmux 1.7 or greater; 1.6 doesn't support querying
> individual environment variables.
>
> Limitation: if you update an environment variable, it's not present in
> other terminals until after the next time you press return in that
> shell.
>
> Limitation: It will invoke tmux before every prompt display, and will do
> so N times, where N is 1 plus the number of variables named in the
> TMUX_ZSH_SHARED tmux env variable.  Optimisation left as an exercise for
> the reader.  (Probably reading the output of show-environment with no
> named variables, so adds 1.6/earlier compatibility; beware that
> environment values are shown raw by tmux, so embedded newlines in a
> variable value will mess up your output, so it's probably only safe done
> the way I did it).
>
> ----------------------------8< cut here >8------------------------------
> # Needs tmux 1.7 to be able to query individual environment variables
>
> if [[ -n $TMUX ]]; then
>    typeset -A latest_seen_tmuxenv
>    function precmd_tmux {
>      local exitstatus=$?
>      local e newenv
>      local -a shared overriden
>      e="$(tmux show-environment TMUX_ZSH_SHARED 2>/dev/null)"
>      [[ $? -ne 0 ]] && return $exitstatus
>      e="${e#TMUX_ZSH_SHARED=}"
>      shared=($=e)
>      for e in ${shared[@]}; do
>        if [[ -n "${(P)e}" && "${(P)e}" != "${latest_seen_tmuxenv[$e]}" ]]; then
>          overriden+=($e)
>          tmux set-environment "$e" "${(P)e}"
>          latest_seen_tmuxenv[$e]="${(P)e}"
>        else
>          newenv="$(tmux show-environment $e 2>/dev/null)"
>          if [[ $? -ne 0 ]]; then
>            if [[ -n "${latest_seen_tmuxenv[$e]}" ]]; then
>              unset $e
>            fi
>            unset latest_seen_tmuxenv[$e]
>            continue
>          fi
>          newenv="${newenv#$e=}"
>          if [[ "$newenv" != "${latest_seen_tmuxenv[$e]}" ]]; then
>            latest_seen_tmuxenv[$e]="$newenv"
>            typeset -g $e="$newenv"
>          fi
>        fi
>      done
>      return $exitstatus
>    }
>
>    precmd_functions+=(precmd_tmux)
> fi
>
> # tmux setenv TMUX_ZSH_SHARED "FOO BAR"
> ----------------------------8< cut here >8------------------------------
>