Conditional variable assignment/ substitution
Bash does support the conditional variable assignment/ substitution e.g. below code snippet
#! /bin/bash
name=${2:-"Juned"}
if [ "$name" != "Juned" ];then
echo "hello $name"
else
echo "bye"
fi
will define the variable name with second command line parameter , but if there is no second command line parameter then the name is defaulted to Juned