What is the significance of $ and {} in `find ${x} *`

Question

I have the following :

x=/
find ${x} *

Now this is similar to find / *

What is the significance of $ and {} in find ${x} *

Answer 1

$... denotes a variable, and when followed by curly parenthesis ${...}, you provide a boundary for the variable so you can run it next to a string literal like:

$ FLAVOUR="cheese"
$ echo "I like ${FLAVOUR}y crisps"
I like cheesey crisps

Without the parenthesis, you would see:

$ echo "I like $FLAVOURy crisps"
I like  crisps

Which, while true, isn't what you really wanted.

Why it's used in your example is beyond me. It isn't required.

---

Curly braces are also used for bash array lookups when you want to specify the index, but this has nothing to do with your example:

$ arr=(*)
$ echo ${arr[3]} # print third item; 1-indexed? blimey.
jumbo-small.jpg
$echo ${arr[@]} # print whole array
glyphicons-halflings.png glyphicons-halflings-white.png jumbo.jpg jumbo-small.jpg