remove-old-files.sh

#!/bin/bash

# Old files removal tool
#
# This script can be used to remove old files (e.g. daily backups)
# so that some are kept.
#
# Files are kept if they are:
# - Less than 30 days old
# - Less than a year old and created on monday
# - Created on 1st of any month
#
# Only files in given path and its subdirectories that end with .gz are
# included.
#
# Empty directories under given path will be also removed after files
# are checked.
#
#
# Dry run usage (doesn't remove any files, just prints statistics):
# ./remove-files.sh <path>
#
# Real usage (removes files):
# ./remove-files.sh <path> --remove
#
# Required commands (must be in path):
# date, stat, rm, bc, find


# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

set -e # exit if any command fails

FILES_PATH=$1
REMOVE=$2

if [ -z "$FILES_PATH" ]; then
    echo "Usage: ./remove-old-backups.sh <backup path> [--remove]"
    exit 1
fi

if [ "$REMOVE" == "--remove" ]; then
    echo "Starting to remove old backups from $FILES_PATH"
else
    echo "Starting to remove old backups from $FILES_PATH DRY RUN (doesn't actually remove anything)"
fi

scanned=0
kept=0
removed=0

CURRENT_TIMESTAMP=`date +%s`
TIMESTAMP_MONTH_AGO=`echo "$CURRENT_TIMESTAMP - (30 * 24 * 60 * 60)" | bc`
TIMESTAMP_YEAR_AGO=`echo "$CURRENT_TIMESTAMP - (12 * 30 * 24 * 60 * 60)" | bc`

# loop through all files and directories in this path, and
# subdirectories

for f in $FILES_PATH/* $FILES_PATH/**/* ; do

    # skip unless $f is a file
    if [ ! -f $f ] ; then
        continue
    fi

    # skip unless $f ends with .gz
    EXT="${f##*.}"
    if [ $EXT != "gz" ] ; then
        continue
    fi

    scanned=$((scanned+1))

    MODIFIED_TIMESTAMP=`stat -c %Y $f`
    MODIFIED_WEEKDAY=`date -d @$MODIFIED_TIMESTAMP +%u` # 1 is monday
    MODIFIED_DAYNUM=`date -d @$MODIFIED_TIMESTAMP +%d` # 01 is first of month

    # keep files that
    # - last modification is on monday and under a year ago
    # - last modification is on first of month
    # - last modification is under 30 days ago

    if [[ ( $MODIFIED_WEEKDAY == "1" && \
            $MODIFIED_TIMESTAMP -ge $TIMESTAMP_YEAR_AGO ) || \
         $MODIFIED_DAYNUM == "01" || \
         $MODIFIED_TIMESTAMP -ge $TIMESTAMP_MONTH_AGO \
       ]] ; then
        kept=$((kept+1))
    else
        if [ "$REMOVE" == "--remove" ]; then
            rm $f
        fi
        removed=$((removed+1))
    fi

done;


if [ "$REMOVE" == "--remove" ]; then
    find $FILES_PATH -type d -empty -delete
    echo "Finished cleaning backups from $FILES_PATH: scanned: $scanned, kept: $kept, removed: $removed"
else
    echo "Finished cleaning backups from $FILES_PATH: scanned: $scanned, kept: $kept, removed: $removed DRY RUN (nothing removed)"
fi