我正在使用 kvm 在开放星云内实例化 debian jessie 机器。我要安装jboss eap和mod_cluster，所以我需要安装apache2服务。
我按照 mod_cluster 快速入门指南设置 /etc/apache2/apache2.conf 文件如下：
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
LoadModule slotmem_module modules/mod_slotmem.so
LoadModule manager_module modules/mod_manager.so
LoadModule proxy_cluster_module modules/mod_proxy_cluster.so
LoadModule advertise_module modules/mod_advertise.so
ServerName master
Listen 10.0.0.6:6666
<VirtualHost 10.0.0.6:6666>
<Directory />
Order deny,allow
Deny from all
Allow from 10.0.0.
</Directory>
KeepAliveTimeout 60
MaxKeepAliveRequests 0
ManagerBalancerName nebula
AdvertiseFrequency 5
<Location /mod_cluster_manager>
Order deny,allow
Deny from all
Allow from 10.0.0.
</Location>
当我运行命令 /etc/init.d/apache2 start 它返回错误时， systemctl status apache2.service -l 向我显示：
apache2.service - LSB: Apache2 web server
Loaded: loaded (/etc/init.d/apache2)
Active: failed (Result: exit-code) since Wed 2015-12-16 15:17:45 CET; 10min ago
Process: 844 ExecStart=/etc/init.d/apache2 start (code=exited, status=1/FAILURE)
Dec 16 15:17:45 debian apache2[844]: Starting web server: apache2 failed!
Dec 16 15:17:45 debian apache2[844]: The apache2 configtest failed. ... (warning).
Dec 16 15:17:45 debian apache2[844]: Output of config test was:
Dec 16 15:17:45 debian apache2[844]: apache2: Syntax error on line 1 of /etc/apache2/apache2.conf: Cannot load modules/mod_proxy.so into server: /etc/apache2/modules/mod_proxy.so: undefined symbol: ap_escape_html
Dec 16 15:17:45 debian apache2[844]: Action 'configtest' failed.
Dec 16 15:17:45 debian apache2[844]: The Apache error log may have more information.
Dec 16 15:17:45 debian systemd[1]: apache2.service: control process exited, code=exited status=1
Dec 16 15:17:45 debian systemd[1]: Failed to start LSB: Apache2 web server.
Dec 16 15:17:45 debian systemd[1]: Unit apache2.service entered failed state.
我无法理解“未定义符号：ap_escape_html”的含义以及如何解决它。
提前感谢您的帮助。
更新 1：我尝试从源代码构建 httpd。我也从源代码安装了 pcre 库，但是当我运行 PREFIX/bin/apachectl -k start 它返回以下错误：
/etc/httpd/bin/httpd: error while loading shared libraries: libpcre.so.1: cannot open shared object file: No such file or directory