起初是访问了某个需要有adobe flash player的主页，结果页面显示需要安装插件，然后我就点了页面上的安装，过程倒是很顺利，一会就装完了，但是无论重启firefox还是还是电脑，刚才装完的插件都没有起作用。
然后就一顿搜索，最后使用下面的安装命令，装完后重启firefox起作用了。
zz@zz:~$ sudo apt-get install flashplugin-installer [sudo] password for zz: Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: linux-headers-4.15.0-60 linux-headers-4.15.0-60-generic linux-image-4.15.0-60-generic linux-modules-4.15.0-60-generic linux-modules-extra-4.15.0-60-generic Use 'sudo apt autoremove' to remove them. Suggested packages: x-ttcidfont-conf ttf-mscorefonts-installer ttf-bitstream-vera | ttf-dejavu ttf-xfree86-nonfree xfs The following packages will be REMOVED: adobe-flash-properties-gtk adobe-flashplugin The following NEW packages will be installed: flashplugin-installer 0 upgraded, 1 newly installed, 2 to remove and 148 not upgraded. Need to get 6,778 B of archives. After this operation, 36.2 MB disk space will be freed. Do you want to continue? [Y/n] y Get:1 http://us.archive.ubuntu.com/ubuntu xenial-updates/multiverse amd64 flashplugin-installer amd64 32.0.0.255ubuntu0.16.04.1 [6,778 B] Fetched 6,778 B in 0s (8,126 B/s) Preconfiguring packages ... (Reading database ... 263946 files and directories currently installed.) Removing adobe-flash-properties-gtk (1:20181120.1-0ubuntu0.16.04.1) ... Removing adobe-flashplugin (1:20181120.1-0ubuntu0.16.04.1) ... Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ... Processing triggers for desktop-file-utils (0.22-1ubuntu5.2) ... Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20180209-0ubuntu1) ... Rebuilding /usr/share/applications/bamf-2.index... Processing triggers for mime-support (3.59ubuntu1) ... Processing triggers for hicolor-icon-theme (0.15-0ubuntu1.1) ... Selecting previously unselected package flashplugin-installer. (Reading database ... 263916 files and directories currently installed.) Preparing to unpack .../flashplugin-installer_32.0.0.255ubuntu0.16.04.1_amd64.deb ... Unpacking flashplugin-installer (32.0.0.255ubuntu0.16.04.1) ... Processing triggers for update-notifier-common (3.168.9) ... flashplugin-installer: processing... flashplugin-installer: downloading http://archive.canonical.com/pool/partner/a/adobe-flashplugin/adobe-flashplugin_20190910.1.orig.tar.gz Get:1 http://archive.canonical.com/pool/partner/a/adobe-flashplugin/adobe-flashplugin_20190910.1.orig.tar.gz [30.6 MB] Fetched 30.6 MB in 4min 11s (122 kB/s) Installing from local file /var/lib/update-notifier/package-data-downloads/partial/adobe-flashplugin_20190910.1.orig.tar.gz Flash Plugin installed. Setting up flashplugin-installer (32.0.0.255ubuntu0.16.04.1) ... zz@zz:~$