gpg-agent 正在运行，但总是提示我输入密码

当我运行 gpg2 时，每次使用时都会提示我输入密码。根据我对gpg-agent手册页的阅读，我应该只在第一次得到提示。

gpg-agent  is a daemon to manage secret (private)
keys independently from any proto-col. It is
used as a backend for gpg and gpgsm as well as
for  a  couple  of other utilities.

The agent is automatically started on demand
by gpg, gpgsm, gpgconf, or gpg-connect-agent.
Thus there is no reason to start it manually.

...

--default-cache-ttl n
    Set the time a cache entry is valid to n
    seconds.  The default  is  600  sec- onds.
    Each  time a cache entry is accessed, the
    entry's timer is reset.  To set an entry's
    maximum lifetime, use max-cache-ttl.

--max-cache-ttl n
    Set the maximum time a cache entry is valid
    to n seconds.  After this time  a cache
    entry will be expired even if it has been
    accessed recently or has been set using
    gpg-preset-passphrase.  The default is 2
    hours (7200 seconds).

如果我没看错，gpg2在我第一次使用它时调用应该提示输入密码，然后，如果我在接下来的 600 秒内再次运行它，我将不会再收到提示。跑步

gpg2 --export-secret-keys --armor [email protected] > /dev/null

给了我这个：

┌─┐
│ Please enter the passphrase to export the OpenPGP secret key:  │
│ "John Doe (asdf) <[email protected]>"                       │
│ 2048-bit RSA key, ID EB7B49EAD38DE665,                         │         
│ created 2018-10-09.                                            │         
│                                                                │         
│                                                                │         
│ Passphrase: _ │
│                                                                │         
│         <OK>                                    <Cancel>       │
└─┘

正在运行的快速ps aux显示：gpg-agent

ps aux | grep gpg-agent
jdoe   14089  0.1  0.1 100884  3588 ?        SLs  18:50   0:07 /usr/bin/gpg-agent --supervised

唉，此后立即再次运行 gpg2 --export-secret-keys...再次提示我输入密码。

更多细节：

• 我在用着pinentry-curses
• 我已经$GPG_TTY在我的.bashrc
• gpg2 --version -> gpg (GnuPG) 2.2.4
• 我已经通读了为什么即使使用 gpg-agent 也会要求 gpg 输入密码？以及如何找出 gpg-agent 缓存的密钥？（比如 ssh-add -l 如何显示缓存的 ssh 密钥），但我并没有完全理解。