问题：安装MYSQL时报错，是因为之前安装时，没有网络，中断过
root@ubuntu:/etc/init.d# sudo apt-get install mysql-server
E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?
采取的办法是：
root@ubuntu:~# lsof /var/lib/dpkg/lock-frontend
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
Output information may be incomplete.
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
apt-get 2564 root 4uW REG 8,1 0 413925 /var/lib/dpkg/lock-frontend
root@ubuntu:~# sudo kill -9 2564 注意‘-9’，如果不加，不会成功
root@ubuntu:~# lsof /var/lib/dpkg/lock-frontend
root@ubuntu:~# sudo apt-get install mysql-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
libaio1 libevent-core-2.1-6 libhtml-template-perl mysql-client-5.7
mysql-client-core-5.7 mysql-server-5.7 mysql-server-core-5.7
Suggested packages:
libipc-sharedcache-perl mailx tinyca
The following NEW packages will be installed:
libaio1 libevent-core-2.1-6 libhtml-template-perl mysql-client-5.7
mysql-client-core-5.7 mysql-server mysql-server-5.7 mysql-server-core-5.7
0 upgraded, 8 newly installed, 0 to remove and 238 not upgraded.
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