$ sudo /usr/bin/pip2 install flask==0.12
Requirement already satisfied: flask==0.12 in /usr/lib64/python2.6/site-packages
Requirement already satisfied: click>=2.0 in /usr/lib/python2.6/site-packages (from flask==0.12)
Requirement already satisfied: Jinja2>=2.4 in /usr/lib/python2.6/site-packages/Jinja2-2.6-py2.6.egg (from flask==0.12)
Requirement already satisfied: Werkzeug>=0.7 in /usr/lib/python2.6/site-packages (from flask==0.12)
Requirement already satisfied: itsdangerous>=0.21 in /usr/lib/python2.6/site-packages (from flask==0.12)
$ python
Python 2.6.6 (r266:84292, Jul 23 2015, 15:22:56)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>>
>>> import flask
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib64/python2.6/site-packages/flask/__init__.py", line 19, in <module>
from jinja2 import Markup, escape
ImportError: No module named jinja2
>>>
我在安装过程中已经满足了要求，然后在导入过程中出现导入错误。为什么？
如果您没有/usr/lib/python2.6/site-packages/jinja2，则可能是先前的安装被中断了。如果是这种情况，在您的位置上，我会尝试删除/usr/lib/python2.6/site-packages/Jinja2-2.6-py2.6.egg并再次安装 flask==0.12。
有一个明显更新的Flask版本可用(以及Python，就此而言(。我想你有理由想要一些更老的东西。