安装lamp环境后，测试数据库连接。
当host使用127.0.0.1时，报错：(HY000/2002): Permission denied。
把host换成localhost后，又报错：SQLSTATE[HY000] [2002] No such file or directory。
最后发现是因为没有关闭selinux，通常情况下载安装完CentOS7后，默认情况下SElinux是启用状态。
[root@rdo ~]# sestatus
SELinux status: enabled
SELinuxfs mount: /sys/fs/selinux
SELinux root directory: /etc/selinux
Loaded policy name: targeted
Current mode: enforcing
Mode from config file: enforcing
Policy MLS status: enabled
Policy deny_unknown status: allowed
Max kernel policy version: 28
如果要临时关闭，可以执行：
setenforce 0此时状态如下：
[root@rdo ~]# sestatus
SELinux status: enabled
SELinuxfs mount: /sys/fs/selinux
SELinux root directory: /etc/selinux
Loaded policy name: targeted
Current mode: permissive
Mode from config file: enforcing
Policy MLS status: enabled
Policy deny_unknown status: allowed
Max kernel policy version: 28
如果要永久关闭，可以修改配置文件/etc/selinux/config，将SELINU置为disabled。
[root@rdo ~]# cat /etc/selinux/config # This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
#SELINUX=enforcing
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
# targeted - Targeted processes are protected,
# minimum - Modification of targeted policy. Only selected processes are protected.
# mls - Multi Level Security protection.
SELINUXTYPE=targeted
修改该配置文件也可以执行下面的命令来完成：
sed -i '/SELINUX/s/enforcing/disabled/' /etc/selinux/config
修改完成后，保存重启，重启后状态如下：
[root@rdo ~]# sestatus
SELinux status: disabled
文章本人亲测有效。
文章转载：https://blog.****.net/eclothy/article/details/48265445