To make git commit --gpg-sign remember your SSH key password (or more accurately, your GPG key passphrase) until you log out, you need to use a credential helper or agent that caches your passphrase. Here’s how you can achieve this:

1. Use gpg-agent to Cache Your Passphrase

gpg-agent is the standard way to cache GPG passphrases. It can be configured to remember your passphrase for a set period or until you log out.

Steps:

1. Edit or create the gpg-agent configuration file: Open or create ~/.gnupg/gpg-agent.conf and add the following lines:

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   default-cache-ttl 34560000
   max-cache-ttl 34560000

   • default-cache-ttl sets the default cache time (in seconds). 34560000 is roughly 1 year, but you can set it to 0 to cache until logout.
   • max-cache-ttl sets the maximum cache time.

2. Restart gpg-agent: Run the following command to restart the agent:

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   gpgconf --kill gpg-agent
   gpgconf --launch gpg-agent

3. Ensure gpg-agent is used by Git: Add the following to your shell configuration file (e.g., ~/.bashrc, ~/.zshrc):

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   export GPG_TTY=$(tty)

   Then, reload your shell configuration:

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   source ~/.bashrc  # or source ~/.zshrc

2. Use ssh-agent for SSH Keys (if applicable)

If you are using an SSH key for GPG signing (via ssh-agent), you can also configure ssh-agent to cache your passphrase.

Steps:

1. Start ssh-agent and add your key:

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   eval "$(ssh-agent -s)"
   ssh-add ~/.ssh/your_private_key

   You will be prompted for your passphrase once, and it will be cached until you log out.

2. Configure Git to use SSH for GPG signing: If you are using SSH for GPG signing (e.g., with gpg.format=ssh), ensure your Git config is set up correctly:

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   git config --global gpg.format ssh
   git config --global user.signingkey ~/.ssh/your_private_key.pub

3. Verify Your Setup

• Test your setup by running:

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  echo "test" | gpg --clearsign

  You should not be prompted for your passphrase if the cache is working.

• Test a signed Git commit:

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  git commit --gpg-sign -m "Test signed commit"

Summary Table