yumって何の言語で記述されているのだろうか?調べてみた。
(CentOS6.7)

console
# which yum /usr/bin/yum
/usr/bin/yum
#!/usr/bin/python import sys try: import yum except ImportError: print >> sys.stderr, """\ There was a problem importing one of the Python modules required to run yum. The error leading to this problem was: %s Please install a package which provides this module, or verify that the module is installed correctly. It's possible that the above module doesn't match the current version of Python, which is: %s If you cannot solve this problem yourself, please go to the yum faq at: http://yum.baseurl.org/wiki/Faq """ % (sys.exc_value, sys.version) sys.exit(1) sys.path.insert(0, '/usr/share/yum-cli') try: import yummain yummain.user_main(sys.argv[1:], exit_code=True) except KeyboardInterrupt, e: print >> sys.stderr, "\n\nExiting on user cancel." sys.exit(1)

pythonで書かれている!

pythonのインストールでpython壊してしまい、/usr/bin/pythonが無いので、yumも当然エラー発生。

console
# yum -bash: /usr/bin/yum: /usr/bin/python: bad interpreter: No such file or directory
console
# /usr/bin/python -bash: /usr/bin/python: No such file or directory

CentOSにデフォルトで入っているpythonは壊さないようにしましょう…