While creating materials for my bash class I needed to create some globbing exercises for my students.
It occured to me that a string operator and a comparison to the null string can be used to check if something is a substring of another value.
Sure, you can use Substring Expansion to see if the substring is at a known location such as "Does the value of $foo start with 'bar'?", but length and location are often unknown.
Say, for instance, I wanted to know if it's a word a Dalek would shriek? Easy to do with regular expressions: grep ate$ /usr/share/dict/words.