113 lines
2.7 KiB
Bash
Executable File
113 lines
2.7 KiB
Bash
Executable File
#!/bin/bash
|
|
#
|
|
# Written by Aaron Lindsay <aaron@aclindsay.com>
|
|
|
|
# These knobs control which backups to keep, and how long to keep them for. A
|
|
# backup is kept if its distance from the UNIX epoch in days divides evenly by
|
|
# BASE^power (where power is some integer 0 < MAX_POWER), and it is less than
|
|
# WINDOW_FACTOR*BASE^power days old.
|
|
BASE=2
|
|
MAX_POWER=16
|
|
WINDOW_FACTOR=4
|
|
|
|
# Returns output if the date passed in as the first argument is not in a format
|
|
# 'date' can understand
|
|
function invalid_date() {
|
|
date -d "$1 + 1 min" +"%s" &> /dev/null
|
|
if [[ $? -ne 0 ]]; then
|
|
echo "invalid"
|
|
fi
|
|
}
|
|
|
|
# Return the number of days which passed between the UNIX epoch and the first
|
|
# argument
|
|
function days_since_epoch() {
|
|
echo $(( $(date -d "$1" +"%s") / (60*60*24) ))
|
|
}
|
|
|
|
# Prints "keep" if the backup with the indicated date should be kept
|
|
function keep_backup() {
|
|
local current_day_count=$1
|
|
local backup_day_count=$2
|
|
local difference=$(( $current_day_count - $backup_day_count ))
|
|
|
|
for (( power=0; power<=$MAX_POWER; power++ )); do
|
|
local factor=$(( $BASE ** $power ))
|
|
local remainder=$(( $backup_day_count % $factor ))
|
|
if [[ $remainder -eq 0 ]] &&
|
|
[[ $difference -le $(($factor * $WINDOW_FACTOR)) ]]; then
|
|
echo "keep"
|
|
return
|
|
fi
|
|
done
|
|
}
|
|
|
|
function usage() {
|
|
cat << EOF
|
|
Usage: $0 options
|
|
|
|
Print the backups which should (or should not with -r) be kept from a list of
|
|
dates passed via stdin.
|
|
|
|
OPTIONS:
|
|
-h Show this message
|
|
-i FILE Read candidate backup dates from FILE instead of stdin
|
|
-d DATE Calculate which backups should be kept from this date instead of
|
|
today
|
|
-r Reverse which dates are displayed (show those which should be
|
|
deleted instead of kept)
|
|
EOF
|
|
}
|
|
|
|
reverse=
|
|
current_date=$(date -I)
|
|
input="/dev/stdin"
|
|
|
|
while getopts "hrd:i:" OPTION; do
|
|
case $OPTION in
|
|
i)
|
|
input=$OPTARG
|
|
if [[ ! -f $input ]]; then
|
|
echo "Error: \"$input\" is not a file" 1>&2
|
|
usage
|
|
exit 1
|
|
fi
|
|
;;
|
|
d)
|
|
current_date=$OPTARG
|
|
if [[ $(invalid_date "$current_date") ]]; then
|
|
echo "Error: \"$current_date\" is not a valid date" 1>&2
|
|
usage
|
|
exit 1
|
|
fi
|
|
;;
|
|
r)
|
|
reverse="true"
|
|
;;
|
|
h)
|
|
usage
|
|
exit
|
|
;;
|
|
?)
|
|
usage
|
|
exit 1
|
|
;;
|
|
esac
|
|
done
|
|
|
|
current_days=$(days_since_epoch "$current_date")
|
|
|
|
while read line; do
|
|
if [[ $(invalid_date "$line") ]]; then
|
|
echo "Error: \"$line\" is not a valid date" 1>&2
|
|
exit 1
|
|
fi
|
|
backup_days=$(days_since_epoch "$line")
|
|
keep=$(keep_backup $current_days $backup_days)
|
|
if [[ -z $reverse ]] && [[ $keep ]]; then
|
|
echo $line
|
|
elif [[ $reverse ]] && [[ -z $keep ]]; then
|
|
echo $line
|
|
fi
|
|
done < $input
|