when you run the script ex- "./alias.sh", it executes in a sub-shell, you need to run it with "source alias.sh" so that the changes made by script are applied to the current env
source alias.sh or . alias.sh (dot alias.sh)
when you run the script ex- "./alias.sh", it executes in a sub-shell, you need to run it with "source alias.sh" so that the changes made by script are applied to the current env