Adds tn.sh script for tmux session creation

scripts/shell/tn.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+DIR_NAME=${PWD##*/}
+
+tmux has-session -t $DIR_NAME 2>/dev/null
+if [ $? -eq 1 ]; then
+  tmux new -s $DIR_NAME
+else
+  echo "Session with current dirname was found. The script will exit now..."
+  exit 1
+fi