经常在一些小细节方面卡壳，先查看一下文件是否有执行属性
[root@localhost ~]# ll /etc/rc.d/rc.local
-rw-r--r-- 1 root root 507 Jun 12 11:01 /etc/rc.d/rc.local
#上面可以看出没有可执行权限，添加以下可执行权限即可
[root@localhost ~]# chmod +x /etc/rc.d/rc.local
[root@localhost ~]# ll /etc/rc.d/rc.local
-rwxr-xr-x 1 root root 507 Jun 12 11:01 /etc/rc.d/rc.local
#执行后，查看已经增加了可执行权限想在系统启动后执行的命令可以添加到/etc/rc.d/rc.local文件
比如启动时同步系统时间
#!/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.
touch /var/lock/subsys/local
#同步系统时间
/usr/sbin/ntpdate cn.pool.ntp.org
