How to run a Cronjob on the First Sunday Every Month
It’s quite ingenious really:
00 09 * * 0 [ $(date +\%d) -le 07 ] && /run/your/script
This runs a cronjob every Sunday at 9 am. The job itself checks if the current
day is less or equal to 07, effectively covering the first seven days of
every month. If true it continues, if false it doesn’t run.