That will be a number between 1 and 10 ($RANDOM only goes to 32767), sleep $[RANDOM/10] would be better. :)

This might be platform dependent though, I can't find any standard RAND_MAX in bash so it's difficult to make this work everywhere.

This works in (da)sh (tweak 2 and 65536 if needed):

    sleep $(( 0x$(xxd -l2 -p /dev/random) * 3600 / 65536 ))

s/\//%/ I assume?

Oops

  s/\//\\%/

yeah.

  sleep $[RANDOM\%3600]