序言：我尝试寻找解决方案，但没有任何效果。
首先，当我运行以下命令时
$ sudo python --version
Python 2.7.5+
对于 python2 和 3 也类似
$ sudo python2 --version
Python 2.7.5+
$ sudo python3 --version
Python 2.7.5+
我得到了完全一样的东西
例如，当我尝试安装 Firefox 时
sudo apt-get install firefox
我明白这个人遇到的问题
首先，这个解决方案对我来说不起作用。相反，我不确定这个人按照你指定的方式到底在说什么。
二、无法重新安装python3
更新
我从源代码重新安装了 python 3.4.3，当我检查 python3 的版本时，我仍然得到 python 2.7.5+。
回复 Michael Lindman
root@bl-bc-120431:/home/lab/Desktop/Python-3.4.3# ls -al /usr/bin/ |grep python
lrwxrwxrwx 1 root root 26 Feb 4 2014 dh_pypy -> ../share/dh-python/dh_pypy
-rwxr-xr-x 1 root root 1056 Sep 19 2013 dh_python2
lrwxrwxrwx 1 root root 29 Feb 4 2014 dh_python3 -> ../share/dh-python/dh_python3
-rwxr-xr-x 1 root root 94 Feb 27 2014 idle-python2.7
lrwxrwxrwx 1 root root 23 Feb 27 2014 pdb2.7 -> ../lib/python2.7/pdb.py
lrwxrwxrwx 1 root root 23 Feb 27 2014 pdb3.3 -> ../lib/python3.3/pdb.py
lrwxrwxrwx 1 root root 31 Feb 4 2014 py3versions -> ../share/python3/py3versions.py
lrwxrwxrwx 1 root root 26 Feb 4 2014 pybuild -> ../share/dh-python/pybuild
lrwxrwxrwx 1 root root 9 Sep 19 2013 python -> python2.7
lrwxrwxrwx 1 root root 9 Sep 19 2013 python2 -> python2.7
-rwxr-xr-x 1 root root 3336168 Feb 27 2014 python2.7
lrwxrwxrwx 1 root root 33 Feb 27 2014 python2.7-config -> x86_64-linux-gnu-python2.7-config
-rwxr-xr-x 1 root root 178 Dec 14 2011 python2.7-pyrexc
lrwxrwxrwx 1 root root 16 Sep 19 2013 python2-config -> python2.7-config
lrwxrwxrwx 1 root root 18 Mar 25 13:57 python3 -> /usr/bin/python2.7
-rwxr-xr-x 1 root root 3928976 Feb 27 2014 python3.3m
lrwxrwxrwx 1 root root 10 Feb 4 2014 python3m -> python3.3m
lrwxrwxrwx 1 root root 16 Sep 19 2013 python-config -> python2.7-config
lrwxrwxrwx 1 root root 29 Sep 19 2013 pyversions -> ../share/python/pyversions.py
-rwxr-xr-x 1 root root 2916 Feb 27 2014 x86_64-linux-gnu-python2.7-config
-rwxr-xr-x 1 root root 2885 Feb 27 2014 x86_64-linux-gnu-python2.7-dbg-config
lrwxrwxrwx 1 root root 33 Sep 19 2013 x86_64-linux-gnu-python-config -> x86_64-linux-gnu-python2.7-config
对 Michael Lindman 的第二次回复
root@bl-bc-120431:/home/lab/Desktop/Python-3.4.3# apt-get install --reinstall python3
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
apparmor-easyprof apt-clone archdetect-deb bogl-bterm dpkg-repack libdebconfclient0
libdebian-installer4 python-xkit python3-icu python3-pam rdate sbsigntool
screen-resolution-extra ubiquity ubiquity-casper ubiquity-frontend-debconf
ubiquity-ubuntu-artwork
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded.
57 not fully installed or removed.
Need to get 0 B/9,166 B of archives.
After this operation, 0 B of additional disk space will be used.
(Reading database ... 313616 files and directories currently installed.)
Preparing to replace python3 3.3.2-14ubuntu1 (using .../python3_3.3.2-14ubuntu1_amd64.deb) ...
/var/lib/dpkg/info/python3.prerm: 5: /var/lib/dpkg/info/python3.prerm: py3clean: not found
dpkg: warning: subprocess old pre-removal script returned error exit status 127
dpkg: trying script from the new package instead ...
/var/lib/dpkg/tmp.ci/prerm: 5: /var/lib/dpkg/tmp.ci/prerm: py3clean: not found
dpkg: error processing /var/cache/apt/archives/python3_3.3.2-14ubuntu1_amd64.deb (--unpack):
subprocess new pre-removal script returned error exit status 127
/var/lib/dpkg/info/python3.postinst: 47: /var/lib/dpkg/info/python3.postinst: py3compile: not found
dpkg: error while cleaning up:
subprocess installed post-installation script returned error exit status 127
Errors were encountered while processing:
/var/cache/apt/archives/python3_3.3.2-14ubuntu1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)