八进制(020)→10

[root@localhost yemo]# echo $((num=020))
16
[root@localhost yemo]# echo $((num=8#20))
16

十六进制(0xff)→10

[root@localhost yemo]# echo $((num=0xff))
255
[root@localhost yemo]# echo $((num=16#ff))
255
[root@localhost yemo]# echo $((num=2#1111111))
127
[root@localhost yemo]# echo $((num=2#11111111))
255

十进制→其他

[root@localhost yemo]# echo "obase=2;338"|bc
101010010
[root@localhost yemo]# echo "obase=8;338"|bc
522
[root@localhost yemo]# echo "obase=16;338"|bc
152