No error checking, just a simple time saver. Converts an ipaddress into hexadecimal suitable for use by tftp tools and pxe booting. The builtin command gethostip does this also, I include the script incase someone finds it useful.
iptohex 10.168.192.134 0AA8C086
Say you have some files named a100 to a200 that you want to rename to b200 to b100 (it really does happen).
y=200 for x in `seq 100 200` do mv a$x b$((y--)) done
seq is a fairly useful tool, it can also take a reversed list.
for x in `seq 200 -1 100` do printf "$x " done