Convert string into hex - iwconfig wifi key

I've played a bit with my wifi command line configuration. The iwconfig command needs the key represented as hexadecimal string, so here is the formula to convert string into hex. The od command does the work and tr command removes spaces:

$ echo -n "mykey" | od -A n -t x1 | tr -d ' '
6d796b6579

Note: we need to escape special shell symbols

$ echo -n "mykey\$\$" | od -A n -t x1 | tr -d ' '
6d796b65792424

As I found out later the string can be given as parameter to the iwconfig key :).