1

I have configured my Gnome terminal on Linux Mint 18.3 to always start tmux by default by adding a couple of lines to my ~/.bashrc. This works extremely well, except that I also run another script through by adding it to my ~/.bashrc (one of those fancy custom welcome messages that show up when I open my terminal). As intended, this script is executed every time I open my terminal since it is defined below the execution of tmux in .bashrc.

The issue is that every time I subdivide a pane in tmux, or every time I create a new tab, this same script is executed again. Ideally, I would like to have it executed only when the Gnome terminal first opens (e.g. every time I would press Ctrl+Alt+T to open the terminal), but not when creating subsequent tabs and panes in an already opened terminal. What would be the best approach to accomplish this, since ~/.bashrc is executed at every new tab and pane?

I have come across a similar question here but that user wants their script executed only at the system startup. Also, their solution of creating a temporary file as a flag seems very hackish to me. Is there a better way of accomplishing what I want?

Edit: I am executing Tmux by adding the following lines to my .bashrc file:

# If not running interactively, do not do anything
[[ $- != *i* ]] && return
# Otherwise start tmux
[[ -z "$TMUX" ]] && exec tmux

Unfortunately, replacing the last one with

if [[ -z "$TMUX" ]]; then
    exec tmux
    my_script
fi

Does not work. In fact, even the test case below does not work; tmux is executed, but neither echo "A" nor echo "B" are:

if [[ -z "$TMUX" ]]; then
    echo "A"
    exec tmux
    echo "B"
fi
gilbertohasnofb
  • 113
  • 6
  • Does [this answer](https://unix.stackexchange.com/a/10690/193028) help? You can detect if the shell is started within tmux or not, so that should allow you to choose which scripts to run. Another option is to configure the **terminal** to run some other command instead of just a plain shell (instead of useing `bashrc` for that), though I have no idea how to do that in Gnome terminal, as I don't use Gnome terminal. – dirkt Sep 27 '20 at 10:27
  • Thank you for your reply. I tried using the solutions discussed in that post but unfortunately it did not work out for me. I will try to research what could be done through gnome terminal, but I am puzzled as to why my simple `.bashrc` solution doesn't work. The main question for me is how to execute a script inside tmux immediately after `exec tmux` is summoned. (I made some edits in my question above) – gilbertohasnofb Sep 27 '20 at 15:27
  • Because `exec` replaces the current process with the called process, so after `exec`, nothing in the script gets executed. Also, even if you drop `exec`, nothing of that will get executed "inside" `tmux`. – dirkt Sep 27 '20 at 17:24
  • @dirkt Thanks for the info. Would you have any suggestion on how to tackle this then? – gilbertohasnofb Sep 27 '20 at 18:23
  • Everything that comes after `[[ -z "$TMUX" ]] && exec tmux` is execute inside tmux though, e.g. `[[ -z "$TMUX" ]] && exec tmux; echo "inside tmux"`. But after the first line the `$TMUX` variable is set and so I can't use that as a conditional for the `echo` in this example (or script in my original case) – gilbertohasnofb Sep 27 '20 at 18:26

1 Answers1

0

For tmux, use tmux set-env to set an environment variable that will be provided to all new panes in that tmux session.

if [[ $- == *i* && $TMUX && ! $_DID_GREET ]]; then
    ponysay "Hello!"
    tmux set-env _DID_GREET 1
fi

There is no equivalent for GNOME Terminal as far as I know (although it might be possible to poke through D-Bus to see whether the terminal window has more than one tab).

u1686_grawity
  • 426,297
  • 64
  • 894
  • 966