# chloe 2020-04:
# apt-cacher-ng assigned to 200:200
# mysql assigned to 201:201
# uid:gid 200:200 assigned to apt-cacher-ng
# uid:gid 201:201 assigned to mysql

# example for mysql on debian:
find . -type d -gid 122 -exec chown -R 201:201 '{}' \;
find . -type f -uid 116 -exec chown 201:201 '{}' \;