I didn't know about: {A..C}{0..3} "This sequence creates every combination of A to C and 0 to 3—i.e. A0, A1, A2, A3, B0, B1, etc." And: echo {a..z..

I didn't know about: {A..C}{0..3} "This sequence creates every combination of A to C and 0 to 3—i.e. A0, A1, A2, A3, B0, B1, etc." And: echo {a..z..2} a c e g i k m o q s u w y "The ..2 bit tells the expansion to only output every second letter."