Bash Brace Expansion
Brace expansion turns one word into many. A list like {a,b,c} gives each item, and a range like {1..5} gives every number from 1 to 5.
Text before and after the braces is added to every item. There must be no spaces inside the braces.
Lists and ranges
echo {1..5}
1 2 3 4 5
echo file{1..3}.txt
file1.txt file2.txt file3.txt
echo {10..0..2}
10 8 6 4 2 0
Create several folders at once
mkdir -p project/{src,docs,tests}
ls project
docs src tests