刚开始出现：error while loading shared libraries: libpng12.so.0: cannot open shared object file: No such file or directory
[root@syxk ~]# find / -name libpng12.so.0
/usr/lib/libpng12.so.0
[root@syxk ~]# cp /usr/lib/libpng12.so.0 /lib64/
接着出现：error while loading shared libraries: libpng12.so.0: wrong ELF class: ELFCLASS32
分析：
[root@syxk lib64]# ldd libpng12.so.0
linux-gate.so.1 => (0xf7763000)
libz.so.1 => /lib/libz.so.1 (0xf7719000)
libm.so.6 => /lib/libm.so.6 (0xf76d7000)
libc.so.6 => /lib/libc.so.6 (0xf750c000)
/lib/ld-linux.so.2 (0xf7764000)
原因：libpng12.so.0是32位的，需要使用64位的才行.
解决办法：yum install libpng12 -y 即可. 详情：https://centos.pkgs.org/7/centos-x86_64/libpng12-1.2.50-10.el7.x86_64.rpm.html