gfs.py

Python 3 implementation of a date-based Grandfather-father-son backup rotation scheme.

This script takes a list of dates (in the form yyyy-mm-ddThh:mm:ss, or other parseable with the strfime(3) format) and returns the dates that should be kept (or removed, using --remove) under the policy given by the positional arguments passed to the script.

It is also possible to integrate gfs.py as a regular Python module.

Requirements

• Python 3.6+

Example

./gfs.py daily=14 weekly=4 montly=3 yearly=2 <dates.txt

This command will read a list of dates from dates.txt, and will filter it by the given set of policies, keeping only the latest date that fits in a maximum number of slots (or groupings) for each cycle:

• 14 slots of daily dates
• 4 slots of weekly dates
• 3 slots of monthly dates
• 2 slots of yearly dates

The new list of dates is printed to the standard output (i.e. the terminal window, when using an interactive terminal).

Usage

$ ./gfs.py --help
usage: gfs.py [-h] [--date-format FORMAT] [--file FILENAME]
              [--keep | --remove]
              cycle=value [cycle=value ...]

Filter dates using the Grandfather-father-son rotation scheme.

positional arguments:
  cycle=value           Set one or more cycles used for rotation, e.g.,
                        daily=14.

optional arguments:
  -h, --help            show this help message and exit
  --date-format FORMAT, -d FORMAT
                        Date format to use to parse the dates (in strftime(3)
                        format). Default:%Y-%m-%dT%H:%M:%S
  --file FILENAME, -f FILENAME
                        Use filename to read a list of dates instead of the
                        standard input; '-' is interpreted as the standard
                        input.
  --keep, -k            Output the dates to keep in the rotation.
  --remove, -r          Output the dates to remove from the rotation.

Available cycles: daily, day, weekly, week, monthly, month, yearly, year

License

See LICENSE.