Set a cron every certain hours between certain hours
Solution 1:
Actually, Alex's (former) solution will run every minute, every 2 hours between 8 am and 3pm. The right solution is:
0 8-17/2 * * * /path/command
Or even:
0 8,10,12,14,16 * * * /path/command
Which of course looks less nice, but still does what requested...
Solution 2:
0 8-17/2 * * * your_command.sh