I have a backup script that creates files named for the day of creation in the format backups_YYYYMMDD.tar.gz
I currently purge everything over 30 days old with a command like this:
find /backups -mtime +30 -name "backups_????????.tar.gz" -delete
How can I alter this to purge only files that were NOT made on the first of the month? i.e. anything matching "backups_??????01.tar.gz" remains.