Best way to choose a random file from a directory in a shell script

Question

What is the best way to choose a random file from a directory in a shell script?

Here is my solution in Bash but I would be very interested for a more portable (non-

Answer 1

Put each line of output from the command 'ls' into an associative array named line and then choose one of those like so...

ls | awk '{ line[NR]=$0 } END { print line[(int(rand()*NR+1))]}'