SHELL

add passphrase to ssh agent

/usr/bin/ssh-add --apple-use-keychain ~/.ssh/id_rsa

how to add passphrase to ssh key

ssh-keygen -p -f ~/.ssh/id_rsa

how to add passphrase to ssh key

ssh -i ~/.ssh/id_rsa localhost

how to add passphrase to ssh key

-p      Requests changing the passphrase of a private key file instead of
         creating a new private key.  The program will prompt for the file
         containing the private key, for the old passphrase, and twice for
         the new passphrase.

 -f filename
         Specifies the filename of the key file.