Randomize lines in a file

The bash shell has a variable called $RANDOM, which outputs a pseudo-random number every time you call it. This allows you to randomize the lines in a file for example:

    for i in `cat unusual.txt`; do echo "$RANDOM $i"; done | sort | sed -r 's/^[0-9]+ //' > randorder.txt

In other words, put a random number on every line, sort the file, then take off the random numbers.