问题是脚本编译的php不支持gd，不能生成动态的验证码？

最终的解决办法是：

1.确定gd，jpeg，png，freetype包都已经安装（基于centos6.7 yum安装）

[root@mcd nginx+php1.9]# rpm -qa | grep jpe

libjpeg-turbo-1.2.1-3.el6_5.x86_64

libjpeg-turbo-1.2.1-1.el6.x86_64

openjpeg-libs-1.3-11.el6.x86_64

libjpeg-turbo-devel-1.2.1-3.el6_5.x86_64

[root@mcd nginx+php1.9]# rpm -qa | grep png

libpng-1.2.49-2.el6_7.x86_64

libpng-devel-1.2.49-2.el6_7.x86_64

libpng-1.2.49-1.el6_2.x86_64

[root@mcd nginx+php1.9]# rpm -qa | grep freetype

freetype-devel-2.3.11-17.el6.x86_64

freetype-2.3.11-17.el6.x86_64

[root@mcd nginx+php1.9]# rpm -qa | grep gd

gdb-gdbserver-7.2-60.el6.x86_64

gdbm-1.8.0-38.el6.x86_64

eggdbus-0.6-3.el6.x86_64

gdm-plugin-smartcard-2.30.4-39.el6.x86_64

gd-devel-2.0.35-11.el6.x86_64

gd-2.0.35-11.el6.x86_64

gdm-2.30.4-39.el6.x86_64

gdb-7.2-60.el6.x86_64

gdm-libs-2.30.4-39.el6.x86_64

gdk-pixbuf2-2.24.1-6.el6_7.x86_64

gdb-7.2-83.el6.x86_64

gdbm-devel-1.8.0-38.el6.x86_64

gdm-plugin-fingerprint-2.30.4-39.el6.x86_64

gdbm-1.8.0-36.el6.x86_64

gdb-gdbserver-7.2-83.el6.x86_64

gdm-user-switch-applet-2.30.4-39.el6.x86_64

gdb-7.2-90.el6.x86_64

php-gd-5.3.3-48.el6_8.x86_64

gdk-pixbuf2-devel-2.24.1-6.el6_7.x86_64

2.编译安装，注意标红的字体

./configure --prefix=/opt/php --with-config-file-path=/opt/php/etc/php5 --with-mysql=mysqlnd --with-pdo-mysql=mysqlnd --with-iconv-dir --with-zlib --with-libxml-dir --enable-xml --enable-magic-quotes --enable-safe-mode --enable-bcmath --enable-shmop --enable-sysvsem --enable-inline-optimization --with-curl --enable-mbregex --enable-fpm --enable-force-cgi-redirect --enable-mbstring --with-mcrypt --enable-ftp --with-gd --with-openssl --with-mhash --enable-pcntl --enable-sockets --with-xmlrpc --enable-zip --enable-soap --without-pear --with-gettext --with-mime-magic --with-freetype-dir --with-jpeg-dir --with-png-dir 

make

make install

3.phpinfo看到结果

gd

生成动态码的php页面正常显示