A backup rotation filter for your shell
ctime parser: check int bounds
make test, fix usage to avoid warnings
make print-slots print filled slots if format and input is provided



You can also use your local clone with git send-email.


Takes an unsorted list of backup names and returns a list of backups for deletion. The backup rotation rules are given via command line args. The backup names need to contain the time and a date(1) like format specifier is required to parse those.

The following example will make prunef keep 7 daily, 4 weekly and 6 monthly backups.

prunef --keep-daily 7 \
       --keep-weekly 4 \
       --keep-monthly 6 \

By default it will parse the dates using the local timezone. The algorithm uses UTC internaly. If the entries are created in UTC use the --utc flag.

To list backups that should be kept use the --list-kept option.

#Backup slots

The algorithm works by creating timestamp slots according to the rules given. The first slot is always now. A slot ends where the next timestamp begins. The slots are filled with entries, that are between a slot timestamp and the following timestamp. If an entry exists, it will be replaced if another matches the slot and is more recent.

Slots may not be filled, if there is no entry matching the timestamps. That means you will only fill all slots, if the backups are created with lower intervals than the lowest slot interval. If for example a backup is created every 2 hours and --keep-hourly 4 is provided, only 2 backups will be kept.

If no arguments are given, only one slot with now as timestamp will be created. Hence the latest backup will never be returned to be pruned.


Required dependencies:

  • go (>= 1.13)
  • scdoc

Compile with make:

$ make


$ make install

For Arch Linux there's also an AUR package available.


You can send patches to the mailing list or use the GitHub Mirror.