Name dump files differently for each day

[sasharevzin]

Here's an example of how you could do this in bash. The below code sorts a list of archive names that are older than a cutoff time, and creates a command to delete them. This could be changed to work with filenames.

Another option would be to use find to look for files created before a certain day. However, the create date could be misleading.

cutoff_date="backup-$(/bin/date -u --iso-8601=seconds -d '-3 months')"
archives="$(/usr/bin/tarsnap --list-archives | /usr/bin/sort)"
cutoff_archives=""
cutoff_command="/usr/bin/tarsnap --humanize-numbers -d"

while IFS=' ' read -r archive; do
    cutoff_archive=$(echo -e "${cutoff_date}\n${archive}" \
            | /usr/bin/sort \
            | /usr/bin/head -n 1 \
            | /bin/grep -v -F "$cutoff_date" || true)
    if [ -z "$cutoff_archive" ]; then
        continue
    fi
    if [ -z "$cutoff_archives" ]; then
        cutoff_archives="${cutoff_archive}"
    else
        cutoff_archives="${cutoff_archives}\n${cutoff_archive}"
    fi
    cutoff_command="${cutoff_command} -f ${cutoff_archive}"
done <<< "$archives"

Originally posted by @auspicacious in https://github.com/Safecast/safecastapi/pull/699/files