Creating a digital signature based on the RSA algorithm in the openssl library?

Question

OpenSSL

Good time. Given tasks
To generate a private (and public key):
I use the command
genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3 -out privkey-ID.pem
But then when I enter the cat privkey-ID.pem command, an error occurs.
the cause of the error who knows tell me.