问题: linux7 /etc/rc.local 不生效：
[root@bogon mysql3306]# uname -a
Linux bogon 3.10.0-862.el7.x86_64 #1 SMP Fri Apr 20 16:44:24 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
在/etc/rc.local上添加如下部分，重启后没有生效：
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi
[root@bogon mysql3306]# cat /etc/rc.local
#!/bin/bash
# THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES
#
# It is highly advisable to create own systemd services or udev rules
# to run scripts during boot instead of using this file.
#
# In contrast to previous versions due to parallel execution during boot
# this script will NOT be run after all other services.
#
# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure
# that this script will be executed during boot.
解决方法：
(1) chmod +x /etc/rc.d/rc.local
(2) systemctl enable rc-local
Loaded: loaded (/usr/lib/systemd/system/rc-local.service; static; vendor preset: disabled)
Active: active (exited) since Sun 2018-11-18 17:27:56 CST; 1h 9min ago
Process: 1039 ExecStart=/etc/rc.d/rc.local start (code=exited, status=0/SUCCESS)
Tasks: 0
Nov 18 17:27:56 bogon systemd[1]: Started /etc/rc.d/rc.local Compatibility.
[root@bogon software]#
(3) systemctl start rc-local
(4) 验证生效：
[root@bogon ~]# cat /sys/kernel/mm/transparent_hugepage/defrag
always madvise [never]
[root@bogon ~]# cat /sys/kernel/mm/transparent_hugepage/enabled
always madvise [never]
[root@bogon ~]#
(5) 重启后验证依然生效