Apache重啟時報警：
AH00112: Warning: DocumentRoot [/usr/local/apache/docs/dummy-host.example.com] does not exist
AH00112: Warning: DocumentRoot [/usr/local/apache/docs/dummy-host2.example.com] does not exist
問題原因：
Apache在配置虛擬主機時會在配置文件中（httpd.conf）開啟虛擬主機的配置文件；
將“ #Include /etc/httpd/extra/httpd-vhosts.conf ”前面的“#”去掉；
而“httpd-vhosts.conf ”中會有兩個配置虛擬主機的例子：
<VirtualHost *:80>
ServerAdmin webmaster@dummy-host.example.com
DocumentRoot "/usr/local/apache/docs/dummy-host.example.com"
ServerName dummy-host.example.com
ServerAlias www.dummy-host.example.com
ErrorLog "logs/dummy-host.example.com-error_log"
CustomLog "logs/dummy-host.example.com-access_log" common
</VirtualHost>
<VirtualHost *:80>
ServerAdmin webmaster@dummy-host2.example.com
DocumentRoot "/usr/local/apache/docs/dummy-host2.example.com"
ServerName dummy-host2.example.com
ErrorLog "logs/dummy-host2.example.com-error_log"
CustomLog "logs/dummy-host2.example.com-access_log" common
</VirtualHost>
這樣Apache在啟動時就會去尋找以上兩個不存在的文件夾，就會報錯。
解決方法：
方法一：新建出不存在的文件夾；
#cd /usr/local/apache
#mkdir -p docs/dummy-host2.example.com #這里是新建文件夾
#mkdir -p docs/dummy-host.example.com
方法二：將“httpd-vhosts.conf ”中的例子注釋掉；
#<VirtualHost *:80>
# ServerAdmin webmaster@dummy-host2.example.com
# DocumentRoot "/usr/local/apache/docs/dummy-host2.example.com"
# ServerName dummy-host2.example.com
# ErrorLog "logs/dummy-host2.example.com-error_log"
# CustomLog "logs/dummy-host2.example.com-access_log" common
#</VirtualHost>
方法三：配置虛擬主機時，不開啟虛擬主機的配置文件，自己新建配置文件；
#vim /etc/httpd/httpd.conf
#Include /etc/httpd/extra/httpd-vhosts.conf
Incloud /etc/httpd/extra/XXX.conf #新建的配置文件一定要與“httpd-vhosts.conf”放在同一個文件夾內
Incloud /etc/httpd/extra/XXX.conf #文件名稱可以自己定義
更改完成之后重啟Apache即可。