当对 apt 存储库条目使用“签名者”选项时，如果密钥不可读，则 apt 会抛出错误。
例子：
deb [arch=amd64 signed-by=/etc/apt/keyrings/hashicorp.gpg] https://apt.releases.hashicorp.com jammy main
sudo chmod 660 /etc/apt/keyrings/hashicorp.gpg
sudo apt-get update
https://apt.releases.hashicorp.com jammy InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DA418C88A3219F7B
sudo chmod 664 /etc/apt/keyrings/hashicorp.gpg
sudo apt-get update
Hit:10 https://apt.releases.hashicorp.com jammy InRelease
为什么是这样？
apt ×1