# Min   Hr   DayOfMonth   Month   DayOfWeek   Command
# ---   --   ----------   -----   ---------   -------
   0     7      29,30        6        *          X
   0     7          *     7-11        *          X
   0     7       1-30       12        *          X

if [[ "$(date +%Y)" != "2009" ]] ; then
    exit
fi

# Make the job executable on 29 June.
0 6 29 6 * chmod +x /path/to/my/job/script

# Run the job between June and December, only if it's executable.
0 7 * 6-12 * test -x /path/to/my/job/script && /path/to/my/job/script

# Disable execution after 30 December.
0 8 30 12 * chmod -x /path/to/my/job/script

10 5 10 * * means run at 5:10 on every 10th of every month.

10 5 * 12 * means run at 5:10 on every day in december

10 5 * * 1  means run at 5:10 every Monday

0 7 * * 6-12 command_X