How do I get the public key of a pem file?

Question

I have a .pem file containing my private key. However, a BitBucket deployment key has this format:

ssh-rsa AAAAB3NzaC3yc2EAAAADAQABAAABAQDfZxX2LXOJlo5MP2tLP4fmQyjIAcATwATFKwM6K3mtT7+LKx1jk6YlFlEcj2CFxJHHTy6LCdDqoVzL3iNcD+mDl7NbcNEHytZNJnFQ5lAHPxDVa9ZbLnmP1OlfUvsQS+jAt7yMSwd8gZ6McOJfp9ZUn+r5LLpjYkF+AMQFPsf+6lhSJaOjOTbsA39OJwlnnSO6HF3W2Om+8Bgdpa/E4En5RZTBwFCAvLaaXY3XgN76xCR24TwTWFicBHWeLdADGFXB7OBOv4y805fNGbNKOl3Yb21mG89aUQlYjobeLqImyIrrEhX36hEdMW/t6zZK/1I0QC//uLa+GjJoeuPW4WY3 ubuntu@Box

It is usually found using:

cat ~/.ssh/id_rsa.pub | pbcopy

How do I extract my public key, in this format, from a .pem file?

Answer 1

Copy the public key to clipboard.

Linux

ssh-keygen -f private.pem -y | xclip 

MacOS

ssh-keygen -f private.pem -y | pbcopy 

Save to file

ssh-keygen -f private.pem -y > public.pub 

Note that if your permissions are vague on the .pem file, then ssh-keygen will generate an empty .pub file.

You can usually fix this with:

chmod 400 private.pem  

Answer 2

JazzCat's answer works. small addition: if your permissions are vague on .pem file, ssh-keygen will generate empty .pub file.

if you see any complains on terminal about private key too open, try to narrow it using chmod 400 private.pem and retry above command.

ps: sorry I don't have permissions to add a comment instead of answer.