Works for me:
docker run --rm -it ubuntu:zesty sh -c 'apt-key fingerprint | grep Ubu' Warning: apt-key output should not be parsed (stdout is not a terminal) uid [ unknown] Ubuntu Archive Automatic Signing Key (2012) <email address hidden> uid [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <email address hidden>
Works for me:
docker run --rm -it ubuntu:zesty sh -c 'apt-key fingerprint | grep Ubu'
Warning: apt-key output should not be parsed (stdout is not a terminal)
uid [ unknown] Ubuntu Archive Automatic Signing Key (2012) <email address hidden>
uid [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <email address hidden>