Add tmux-guard

This function executes its arguments only if within a ~tmux~ session

zshrc.org

@@ -157,7 +157,19 @@ setup-pi-webcam()
 :END:
 
 *** Misc helpers                                           :pi:daily:android:
-
+    - tmux guard
+      This function checks if we are in a tmux session before
+      executing the command; otherwise print an error and bail out
+#+begin_src sh
+  tmux-guard()
+  {
+ if [[ -v TMUX ]]; then
+    $@
+  else
+      echo tmux-guard: ensure you are in a tmux session to run $@
+  fi
+  }
+#+end_src
     - wttr.in
     #+begin_src sh
      wttr()