How to Public Key Pinning

Please let me know that it's possible to generate the PINs by accessing the server with PuTTY via SSH and the run? [root@na ~]# openssl rsa -in my-key-file.key -outform der -pubout | openssl dgst -sha256 -binary | openssl enc -base64 Error opening Private Key my-key-file.key 140399466469280:error:02001002:system library:fopen:No such file or directory:bss_file.c:402:fopen('my-key-file.key','r') 140399466469280:error:20074002:BIO routines:FILE_CTRL:system lib:bss_file.c:404: unable to load Private Key 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= [root@na ~]# openssl dgst -sha256 -binary public.key | openssl enc -base64 public.key: No such file or directory [root@na ~]#