t in ~/.local/bin/t

t

#!/bin/bash

t () { # set $SHELL fish if it is not, attach tmux session if exists
        if ! hash tmux 2>/dev/null; then
                echo tmux is not installed, please install it!
                return 1
        fi

        if [ $(basename $SHELL) != "fish" ]; then
                if [ -f ~/anaconda3/bin/fish ]; then
                        export SHELL=~/anaconda3/bin/fish
                elif hash fish 2>/dev/null; then
                        export SHELL=$(which fish)
                else
                        echo "No fish is installed, using old $SHELL as SHELL!"
                fi
        fi

        # attach a session if it exists, it failed, tmux a new one, if failed, echo message
        tmux attach 2>/dev/null || tmux 2>/dev/null || echo "Already inside a tmux session!"
}

t