История изменений

SEQ=$(echo -e '0\n00\n000\n0000' | sed -n -r ':st; p; s/^9+$/&/; t; ti9; :i9; s/9(x*)$/x\1/; ti9; s/ (x*)$/ 1\1/; tf; s/0(x*)$/1\1/; tf; s/1(x*)$/2\1/; tf; s/2(x*)$/3\1/; tf; s/3(x*)$/4\1/; tf; s/4(x*)$/5\1/; tf; s/5(x*)$/6\1/; tf; s/6(x*)$/7\1/; tf; s/7(x*)$/8\1/; tf; s/8(x*)$/9\1/; tf; :f; s/x/0/; tf; bst')

echo -e '0\n00\n000\n0000' | sed -n -r ':st; p; s/^9+$/&/; t; ti9; :i9; s/9(x*)$/x\1/; ti9; s/ (x*)$/ 1\1/; tf; s/0(x*)$/1\1/; tf; s/1(x*)$/2\1/; tf; s/2(x*)$/3\1/; tf; s/3(x*)$/4\1/; tf; s/4(x*)$/5\1/; tf; s/5(x*)$/6\1/; tf; s/6(x*)$/7\1/; tf; s/7(x*)$/8\1/; tf; s/8(x*)$/9\1/; tf; :f; s/x/0/; tf; bst'