Also check for gpg-agent

Re-use ssh-agent and/or gpg-agent between logins.
More information: <http://funtoo.org/Keychain>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

keychain --agents "{{gpg,ssh}}"

click the source code to copy install keychain on any operating system with command-not-found.com