To be able to use gpg commit signing with emacs running in terminal, pinentry loopback mode should be enabled for gpg agent.

1. Add pinentry-mode loopback to ~/.gnupg/gpg.conf
2. Add allow-loopback-entry to ~/.gnupg/gpg-agent.conf
3. Reload the agent: gpgconf –reload gpg-agent

References:

• stackoverflow answer
• random blog post site seems abandoned so the link may not be accessible by the time you’re reading this