近日朋友向我求助说是在CentOS6中编译安装了python2.7后面不知怎么搞的yum也用不了的，本以为很简单的事情，把yum里的头替换一下就好了，结果事情不是那个简单。
参考这篇文章重装 https://www.lizenghai.com/archives/17330.html,所使用的包如下：
libxml2-python-2.7.6-21.el6_8.1.x86_64.rpm
python-2.6.6-66.el6_8.x86_64.rpm
python-backports-1.0-5.el6.x86_64.rpm
python-backports-ssl_match_hostname-3.4.0.2-5.el6.noarch.rpm
python-chardet-2.2.1-1.el6.noarch.rpm
python-devel-2.6.6-66.el6_8.x86_64.rpm
python-iniparse-0.3.1-2.1.el6.noarch.rpm
python-libs-2.6.6-66.el6_8.x86_64.rpm
python-pycurl-7.19.0-9.el6.x86_64.rpm
python-setuptools-0.6.10-4.el6_9.noarch.rpm
python-urlgrabber-3.9.1-11.el6.noarch.rpm
rpm-build-4.8.0-59.el6.x86_64.rpm
rpm-libs-4.8.0-59.el6.x86_64.rpm
rpm-python-4.8.0-59.el6.x86_64.rpm
yum-3.2.29-81.el6.centos.noarch.rpm
yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
yum-plugin-aliases-1.1.30-41.el6.noarch.rpm
yum-plugin-fastestmirror-1.1.30-41.el6.noarch.rpm
yum-utils-1.1.30-41.el6.noarch.rpm
下面这些是一些记录，看不懂可忽略这一段
rpm -qa|grep python|xargs rpm -ev --allmatches --nodeps ##强制清除已安装的程序及其关联
whereis python |xargs rm -frv ##删除所有残余文件 ##xargs，允许你对输出执行其他某些命令
whereis python ##验证删除，返回无结果说明清除干净
删除现有的yum
[root@localhost rx]# rpm -qa|grep yum
yum-metadata-parser-1.1.2-16.el6.x86_64
yum-plugin-aliases-1.1.30-41.el6.noarch
yum-plugin-fastestmirror-1.1.30-41.el6.noarch
yum-plugin-protectbase-1.1.30-41.el6.noarch
yum-3.2.29-81.el6.centos.noarch
yum-utils-1.1.30-41.el6.noarch
rpm -qa|grep yum|xargs rpm -ev --allmatches --nodeps
创建一个目录：python-need-pkg，将这些包下载下来,我是用centos6.10 DVD1 ios 镜像中提取的包。下载响应的包（注意：根据自己的系统下载，源中版本会更新，具体查看URL中的版本再下载！）
5.执行命令安装
1>执行这一步的时候没有依赖问题
rpm -Uvh --replacepkgs python*.rpm
行这一步的时候报依赖问题，有两个，
rpm -Uvh --replacepkgs rpm-python.rpm yum.rpm
error: Failed dependencies:
libxml2-python is needed by yum-utils-1.1.30-41.el6.noarch
rpm -ivh --force yum-utils-1.1.30-41.el6.noarch.rpm
find /usr/lib64/ -type f -name "*.so" | xargs nm -AD | grep PyUnicodeUCS4_AsUTF8String
/usr/lib64/python2.6/lib-dynload/_sqlite3.so: U PyUnicodeUCS4_AsUTF8String
/usr/lib64/python2.6/lib-dynload/cPickle.so: U PyUnicodeUCS4_AsUTF8String
/usr/lib64/python2.6/site-packages/rpm/_rpmmodule.so: U PyUnicodeUCS4_AsUTF8String
rpm -qf /usr/lib64/python2.6/lib-dynload/_sqlite3.so
python-libs-2.6.6-66.el6_8.x86_64
rpm -qf /usr/lib64/python2.6/lib-dynload/cPickle.so
python-libs-2.6.6-66.el6_8.x86_64
rpm -qf /usr/lib64/python2.6/site-packages/rpm/_rpmmodule.so
rpm-python-4.8.0-59.el6.x86_64
nm -AD /lib/libpython2.6.so.1.0 | grep PyUnicodeUCS4_AsUTF8String
libpython2.6.so.1.0 => /usr/lib64/libpython2.6.so.1.0 (0x00007f139db99000)
libpython2.6.so.1.0 => /lib/libpython2.6.so.1.0 (0x00007f6be9933000)
libnssutil3.so => /usr/lib64/libnssutil3.so (0x00007f139cb90000)
libnssutil3.so => /usr/lib/libnssutil3.so (0x00007f6be892a000)
后面重装了系统自己带的python2.6.6及yum也还是报 /usr/lib64/python2.6/site-packages/rpm/_rpmmodule.so undefined symbol:PyUnicodeUCS4_AsUTF8String
后面自己在虚拟机中安装了一个干净的CentOS6.10对比才发现问题所在。下面这个是干净系统的 ldd
[root@localhost ~]# ldd /usr/lib64/python2.6/site-packages/rpm/_rpmmodule.so
linux-vdso.so.1 => (0x00007fff9c3e9000)
librpm.so.1 => /usr/lib64/librpm.so.1 (0x00007f6a00ddf000)
libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f6a00bc0000)
libcap.so.2 => /lib64/libcap.so.2 (0x00007f6a009bb000)
libacl.so.1 => /lib64/libacl.so.1 (0x00007f6a007b3000)
libdb-4.7.so => /lib64/libdb-4.7.so (0x00007f6a0043e000)
librpmio.so.1 => /usr/lib64/librpmio.so.1 (0x00007f6a0020e000)
libnss3.so => /usr/lib64/libnss3.so (0x00007f69ffec6000)
libbz2.so.1 => /lib64/libbz2.so.1 (0x00007f69ffcb5000)
libz.so.1 => /lib64/libz.so.1 (0x00007f69ffa9e000)
libelf.so.1 => /usr/lib64/libelf.so.1 (0x00007f69ff888000)
libpopt.so.0 => /lib64/libpopt.so.0 (0x00007f69ff67f000)
liblzma.so.0 => /usr/lib64/liblzma.so.0 (0x00007f69ff45d000)
liblua-5.1.so => /usr/lib64/liblua-5.1.so (0x00007f69ff230000)
libm.so.6 => /lib64/libm.so.6 (0x00007f69fefac000)
libpython2.6.so.1.0 => /usr/lib64/libpython2.6.so.1.0 (0x00007f69fec05000)
librt.so.1 => /lib64/librt.so.1 (0x00007f69fe9fd000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f69fe7e0000)
libc.so.6 => /lib64/libc.so.6 (0x00007f69fe44b000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f69fe247000)
/lib64/ld-linux-x86-64.so.2 (0x00005617d7672000)
libattr.so.1 => /lib64/libattr.so.1 (0x00007f69fe042000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f69fde2b000)
libnssutil3.so => /usr/lib64/libnssutil3.so (0x00007f69fdbfc000)
libplc4.so => /lib64/libplc4.so (0x00007f69fd9f7000)
libplds4.so => /lib64/libplds4.so (0x00007f69fd7f2000)
libnspr4.so => /lib64/libnspr4.so (0x00007f69fd5b3000)
libutil.so.1 => /lib64/libutil.so.1 (0x00007f69fd3af000)对比发现这两处不一样：
libpython2.6.so.1.0 => /usr/lib64/libpython2.6.so.1.0 (0x00007f139db99000)
libpython2.6.so.1.0 => /lib/libpython2.6.so.1.0 (0x00007f6be9933000)
libnssutil3.so => /usr/lib64/libnssutil3.so (0x00007f139cb90000)
libnssutil3.so => /usr/lib/libnssutil3.so (0x00007f6be892a000)
解决它：
cd /etc/ld.so.conf.d/
echo “/usr/lib64/” > libnssutil3.conf
echo “/usr/lib64/” > libpython2.6.conf
echo “/lib64/” > libdb-4.7.conf
又遇到 无法 import time 的问题，解决方法：
vim /etc/profile.d/python.sh export PYTHONPATH=$PYTHONPATH:/usr/lib64/python2.6:/usr/lib64/python2.6/lib-dynload/