The 2.X branch of [[GnuPG]] comes with [gpg-agent][] for caching
passphrases.  The documentation is good, but here are my notes
outlining my usual usage.

Add the following to your `~/.bashrc` (see [[dotfiles]] for fancy
dotfiles maintenance):

    if [ -f "${HOME}/.gnupg/agent-info" ]; then
      source "${HOME}/.gnupg/agent-info"
    fi

Start the agent with

    $ GPG_TTY=$(tty)
    $ gpg-agent --daemon --write-env-file "${HOME}/.gnupg/agent-info"
    $ echo "GPG_TTY='${GPG_TTY}'; export GPG_TTY" >> "${HOME}/.gnupg/agent-info"
    $ source "${HOME}/.gnupg/agent-info"

The `GPG_TTY` bit will spawn the `pinentry` call in the designated
TTY.  This avoids troublesome issues like pinentry clobbering [[Mutt]]
if they are both using ncurses.

I didn't like any of the pinentry programs available on my system, so
I wrote my own: [[pinentry.py]].  To use my script, save it somewhere
on your system and add a line like the following to your
`~/.gnupg/gpg-agent.conf`.

    pinentry-program /path/to/pinentry.py

When you are done with the agent, kill it with

    $ killall gpg-agent
    $ rm -f "${HOME}/.gnupg/agent-info"

[gpg-agent]: http://www.gnupg.org/documentation/manuals/gnupg/Invoking-GPG_002dAGENT.html

[[!tag tags/linux]]
[[!tag tags/tools]]