安装PHP时显示，xml2-config not found
这里需要安装的是libxml2-dev软件包（该软件为Ubuntu-Server自带的，需要使用Ubuntu-Server光盘安装），操作如下：
sudo apt-get install
libxml2-dev
库文件安装完成后，重新配置PHP
编译完成后将会看到“Thank you for using PHP.”的字样，表明PHP已经配置成功了。
错误1：Cannot find OpenSSL's <evp.h>
解决：yum install openssl openssl-devel
ln -s /usr/lib64/libssl.so /usr/lib/
错误2：configure: error: xml2-config not found. Please check your libxml2 installation.
解决：libxml2已经安装，还报这个错误，还需要安装libxml2-devel
错误3：error: Please reinstall the BZip2 distribution
解决：yum -y install bzip2-devel
错误4：checking for cURL in default path... not found
解决：yum -y install curl-devel
5：configure: error: jpeglib.h not found.
：yum -y install libjpeg-devel
6：configure: error: png.h not found.
：yum -y install libpng-devel
7：Configure: error: freetype.h not found.
：yum install freetype-devel
8：configure: error: Unable to locate gmp.h
：yum -y install gmp-devel
9：configure: error: mcrypt.h not found. Please reinstall libmcrypt.
：wget https://nchc.dl.sourceforge.net/project/mcrypt/Libmcrypt/2.5.8/libmcrypt-2.5.8.tar.gz
tar zxflibmcrypt-2.5.8.tar.gz
cdlibmcrypt-2.5.8
./configure
make && make install
10：configure: error: Don't know how to define struct flock on this system, set --enable-opcache=no
：编辑 /etc/ld.so.conf 加入/usr/local/lib，在执行ldconfig。
这个比较麻烦，参考http://www.68idc.cn/help/jiabenmake/qita/2014022169481.html
11：configure: error: Please reinstall readline - I cannot find readline.h
：yum -y install readline-devel
12：configure: error: xslt-config not found. Please reinstall the libxslt >= 1.1.0 distribution
：yum -y install libxslt-devel