For example, the description of crontab for deleting files older than 7 days under the /path/to/backup/ every day at 4:02 AM is as follows.

02 4 * * * find /path/to/backup/* -mtime +7 -exec rm {} \;

Please make sure before executing rm whether targets are intended files. You can check the targets by specifying -ls as the argument of find.

find /path/to/backup/* -mtime +7 -ls

mtime means the last modification timestamp and the results of find may not be the expected file depending on the backup method.

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