Retrieving the Public Key for Key Pair on Linux or Mac OS

ssh-keygen command can be used on Linux or Mac OS to retrieve the public key from the private SSH key:

$ ssh-keygen -y -f MyKeyPair.pem 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQChauLwkBK/vIiFY/t7uY6lzxESqZkZNvCAA3L42OH2fWzKptqGF+N32zjmLLSPFpYjoEHoHpi5e7yypTmiljtHcKUTwJTs3xclQrApCQvR+LneOi/5P5WaYl61G76osJesXiunLTa+RVr3LDR96LjPcql7JDnuh1RFhDqZ87nDfcGmXGV8iG7w3bk3R/2LuzzMYTgEVdv91S1OF1roH1baPXSV8MaYbOKhMUqV61+eP6/F5ZhT5Gk0BKX1KnQ3/gbgMqjMWRMZzYUeVjUbC52lYwrrBTQX5tHphAJtOTNJ/CpyuEuZ7ED+XYhX9Q1DNOZ47K51xbg5lsnyOBYSUqHz

-y – This option will read a private OpenSSH format file and print its public key.
-f – Specifies the filename of the key file.