ash: # echo $((16#10)) 16 # echo $((16#a)) -sh: arithmetic syntax error bash: $ echo $((16#10)) 16 $ echo $((16#a)) 10
Fixed by commit 3004510fd (ash: fix BASE##nn bashism to accept letter 'digits' for bases > 9) in release 1.31.1. (And by commit ca1ce4b9f in master.)