random limit | seed ?seedval?
          Generate a pseudorandom integer number greater than  or
          equal  to  zero and less than limit.  If seed is speci-
          fied, then the command resets the random number genera-
          tor  to a starting point derived from the seedval. This
          allows one to reproduce pseudorandom  number  sequences
          for  testing purposes.  If seedval is omitted, then the
          seed is set to a value based on  current  system  state
          and  the current time, providing a reasonably interest-
          ing and ever-changing seed.

          This command is provided by Extended Tcl.