尝试在Debian Stretch服务器中接收密钥时,出现以下错误: sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF Executing: /tmp/apt-key-gpghome.4B7hWtn7Rm/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF gpg: failed to start the dirmngr '/usr/bin/dirmngr': No such file or directory gpg: connecting dirmngr at '/tmp/apt-key-gpghome.4B7hWtn7Rm/S.dirmngr' failed: No such file or directory gpg: keyserver receive failed: No dirmngr
执行此操作时apt-get upgrade,有时会收到一条消息,指出“以下软件包已保留”。例如: $ sudo apt-get upgrade Reading package lists... Done Building dependency tree Reading state information... Done The following packages have been kept back: linux-headers-server linux-image-server linux-server 0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded. 这到底是什么意思?显然,这些软件包已被保留并且没有安装,但是为什么呢? 接下来的问题是:如何升级这些保留的软件包?