clean up your GnuPG keyring

For reasons too annoying to explain, my GnuPG keyring was huge. It was taking a long time to find keys, and most of them weren’t ones I’d use. So I wrote this little script that strips out all of the keys that aren’t

  1. yours, or
  2. signatories to your key.

The script doesn’t actually delete any keys. It produces shell-compatible output that you can pipe or copy to a shell. Now my keyring file is less than 4% the size (or more precisely, 37‰) of the size it was before.

# - clean up all the excess keys

# my key should probably be the first secret key listed
mykey=$(gpg --list-secret-keys | grep '^sec' | cut -c 13-20 | head -1)
    [ -z $mykey ]
    # exit if no key string
    echo "Can't get user's key ID"
    exit 1

# all of the people who have signed my key
mysigners=$(gpg --list-sigs $mykey | grep '^sig' | cut -c 14-21 | sort -u) 

# keep all of the signers, plus my key (if I haven't self-signed)
keepers=$(echo $mykey $mysigners | tr ' ' '\012' | sort -u)

# the keepers list in egrep syntax: ^(key|key|…)
keepers_egrep=$(echo $keepers | sed 's/^/^(/; s/$/)/; s/ /|/g;')

# show all the keepers as a comment so this script's output is shell-able
echo '# Keepers: ' $keepers

# everyone who isn't on the keepers list is deleted
deleters=$(gpg --list-keys | grep '^pub'|  cut -c 13-20 | egrep -v ${keepers_egrep})

# echo the command if there are any to delete
# command is interactive
    [ -z $deleters ]
    echo "# Nothing to delete!"
    echo 'gpg --delete-keys' $deleters