Решено RHEL 7.1: Настройка VirtualHost Apache

<VirtualHost *:80>
 
ServerName vash_site_1.com
 ServerAlias www.vash_site_1.com
 DocumentRoot /www/vash_site_1
 ErrorLog /www/logs/vash_site_1.error.log
 CustomLog /www/logs/vash_site_1.access.log common

<Directory /www/vash_site_1
Options FollowSymLinks
AllowOverride All
Require all granted
</Directory>

</VirtualHost>

<VirtualHost *:80>

ServerName vash_site_2.com
ServerAlias www.vash_site_2.com
DocumentRoot /www/vash_site_2
ErrorLog /www/logs/vash_site_2.error.log
CustomLog /www/logs/vash_site_2.access.log common

<Directory /www/vash_site_2>
Options FollowSymLinks
AllowOverride All
Require all granted
</Directory>

</VirtualHost>

<VirtualHost *:80>
ServerName vash_site_1.com
ServerAlias www.vash_site_1.com
DocumentRoot /www/vash_site_1
ErrorLog /www/logs/vash_site_1.error.log
CustomLog /www/logs/vash_site_1.access.log common

<Directory /www/vash_site_1>
php_admin_value open_basedir '/www/vash_site_1:/tmp:/var/lib/php/session:/www/vash_site_1/tmp:/www/vash_site_1/log'
php_admin_value disable_functions 'show_source, system, shell_exec, passthru, exec, phpinfo, popen, proc_open'
Options FollowSymlinks
AllowOverride All
Require all granted
</Directory>
</VirtualHost>

<VirtualHost *:80>
ServerName vash_site_2.com
ServerAlias www.vash_site_2.com
DocumentRoot /www/vash_site_2
ErrorLog /www/logs/vash_site_2.error.log
CustomLog /www/logs/vash_site_2.access.log common

<Directory /www/vash_site_1>
php_admin_value open_basedir '/www/vash_site_2:/tmp:/var/lib/php/session:/www/vash_site_2/tmp:/www/vash_site_2/log'
php_admin_value disable_functions 'show_source, system, shell_exec, passthru, exec, phpinfo, popen, proc_open'
Options FollowSymlinks
AllowOverride All
Require all granted
</Directory>
</VirtualHost>