How can I tell if I'm logged in to a private Docker registry from a script?

Question

How can I tell whether or not I\'m logged in to a private Docker registry server from a script? In other words, has docker login some.registry.com been run success

Answer 1

When you do the

Docker login  -u  -p  

command from your terminal, you will have a response: (stored in $?)

0
Login Succeeded

if you were successful.

In your shell script, you could just look at the response you're receiving, if it does not equal 0, you've failed to login.

sudo docker login  -u  -p 
if [ $? -ne 0 ]; then
    echo Login failed!
else
    echo Login OK!
fi