Script for shrinking polipo cache

poliposhrink.sh

#!/usr/bin/env zsh
# using GNU utils so not completely portable
# sort -h [compare human readable numbers] works only with gnu sort
# also gfind ... -delete, numfmt are GNU utils
# terminal-notifier, polipo - must be in the path
# For the reference
# gfind -mtime means that the content was modified. This date can be manually changed (e.g. with touch).
# gfind -ctime means that either the content was changed, or the file's metadata (permission, owner, etc).
# -mtime n
#    evaluate as true if the file modification time subtracted
#    from the initialization time, divided by 86400 (with any remainder discarded), is n.
# gfind -size  - is similarly confusing with skiping reminders

cache_dir="/usr/local/var/cache/polipo"
declare -i folders_count
declare -i cache_size_bytes 
declare -i cache_size_treshold

cd $cache_dir
cache_size_treshold=$(numfmt --from=iec 256.0M)
cache_size=$(du -hs $cache_dir | gawk {'print $1'})
cache_size_bytes=$(numfmt --from=iec $cache_size)
folders_count=$(gfind $cache_dir -type d | wc -l)

echo $(date +"%c")
echo "cache size: $cache_size ($cache_size_bytes bytes)"
echo "$folders_count folders in polipo cache"

# if test $folders_count -gt 255 OR
if test $cache_size_bytes -gt $cache_size_treshold
    then
# list largest folders (and files if using du without gfind -type d but it is always folders here)
        du -hc $cache_dir | gsort -h | tail -n 12
# Tell polipo we're messing with the cache
        killall -s SIGUSR1 polipo
        sleep 1
        # find and remove folders older then 24hrs+
        # gfind $cache_dir -maxdepth 2 -type d -ctime +1 | xargs rm -rf
        # OR
        # first delete files larger then 10MB (mostly binary downloads like AppStore etc.)
        gfind $cache_dir -size +10M -delete
        # then delete files older then 2+ days - looking deeper
        gfind $cache_dir -maxdepth 3 -type f -ctime +2 -delete
        # and finally delete folders not modified in 24+ hours 
        # = domains not visited in last 24hrs so probably visited only once while browsing
        gfind $cache_dir -maxdepth 2 -type d -ctime +1 -exec rm -rf {} +
        # OR [gnu find only]
        # gfind $cache_dir -maxdepth 2 -type d -ctime +1 -delete
        # and tell polipo to clean up
        polipo -x
# All clear, we're done messing with the cache
        killall -s SIGUSR2 polipo
        terminal-notifier -title "poliposhrink.sh" \
            -message "poliposhrink just trimmed polipo cache. Check log for details." \
            -appIcon "$HOME/Pictures/Icons/flat-osx/Osx-Trash-Full.icns"
        # Check out
        echo "$(gfind $cache_dir -type d | wc -l) folders left in polipo cache"
        echo "$(du -hs $cache_dir | gawk {'print $1'}) left in polipo cache"
fi