OpenSSL command to manage PKCS#10 Certificate Signing Requests. More information: https://www.openssl.org/docs/manmaster/man1/openssl-req.html.
openssl req -new -sha256 -key filename.key -out filename.csr
openssl req -new -x509 -newkey rsa:4096 -keyout filename.key -out filename.cert -subj "/C=XX/CN=foobar" -days 365