PIP 只会将包安装到 Python 2

Question

我有一台运行 Ubuntu 16.04 的计算机，我正在尝试使用 Python。我需要安装 pyserial 包。跑步 pip install pyserial 没有问题，但是当我尝试在 python 3 (3.9.6) 中导入包时，我收到一个错误，即没有名为 serial 的模块。当我尝试运行python3 -m pip install pyserial 时，我收到一条错误消息/usr/local/bin/python3: No module named pip。我已经运行 sudo apt-get install -y python3-pip 没有错误，但这并不能解决 pip 的问题。与运行 pip3 install pyserial 而不仅仅是 pip 相同。我最近用 python 3.9.6 替换了 python 3.5.2，当我这样做 python3 -v 时，我收到一条很长的错误消息（发布在下面），所以我认为这与它有关，但我只是不确定.我不知道安装是否搞砸了，是否有一些事情需要清理，或者是否还有其他事情发生。

import _frozen_importlib # frozen
import _imp # builtin
import '_thread' # <class '_frozen_importlib.BuiltinImporter'>
import '_warnings' # <class '_frozen_importlib.BuiltinImporter'>
import '_weakref' # <class '_frozen_importlib.BuiltinImporter'>
import '_io' # <class '_frozen_importlib.BuiltinImporter'>
import 'marshal' # <class '_frozen_importlib.BuiltinImporter'>
import 'posix' # <class '_frozen_importlib.BuiltinImporter'>
import '_frozen_importlib_external' # <class '_frozen_importlib.FrozenImporter'>
# installing zipimport hook
import 'time' # <class '_frozen_importlib.BuiltinImporter'>
import 'zipimport' # <class '_frozen_importlib.FrozenImporter'>
# installed zipimport hook
# /usr/local/lib/python3.9/encodings/__pycache__/__init__.cpython-39.pyc matches /usr/local/lib/python3.9/encodings/__init__.py
# code object from '/usr/local/lib/python3.9/encodings/__pycache__/__init__.cpython-39.pyc'
# /usr/local/lib/python3.9/__pycache__/codecs.cpython-39.pyc matches /usr/local/lib/python3.9/codecs.py
# code object from '/usr/local/lib/python3.9/__pycache__/codecs.cpython-39.pyc'
import '_codecs' # <class '_frozen_importlib.BuiltinImporter'>
import 'codecs' # <_frozen_importlib_external.SourceFileLoader object at 0x7f41506b8700>
# /usr/local/lib/python3.9/encodings/__pycache__/aliases.cpython-39.pyc matches /usr/local/lib/python3.9/encodings/aliases.py
# code object from '/usr/local/lib/python3.9/encodings/__pycache__/aliases.cpython-39.pyc'
import 'encodings.aliases' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150653ca0>
import 'encodings' # <_frozen_importlib_external.SourceFileLoader object at 0x7f41506b8460>
# /usr/local/lib/python3.9/encodings/__pycache__/utf_8.cpython-39.pyc matches /usr/local/lib/python3.9/encodings/utf_8.py
# code object from '/usr/local/lib/python3.9/encodings/__pycache__/utf_8.cpython-39.pyc'
import 'encodings.utf_8' # <_frozen_importlib_external.SourceFileLoader object at 0x7f41506b8940>
import '_signal' # <class '_frozen_importlib.BuiltinImporter'>
# /usr/local/lib/python3.9/encodings/__pycache__/latin_1.cpython-39.pyc matches /usr/local/lib/python3.9/encodings/latin_1.py
# code object from '/usr/local/lib/python3.9/encodings/__pycache__/latin_1.cpython-39.pyc'
import 'encodings.latin_1' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150653d90>
# /usr/local/lib/python3.9/__pycache__/io.cpython-39.pyc matches /usr/local/lib/python3.9/io.py
# code object from '/usr/local/lib/python3.9/__pycache__/io.cpython-39.pyc'
# /usr/local/lib/python3.9/__pycache__/abc.cpython-39.pyc matches /usr/local/lib/python3.9/abc.py
# code object from '/usr/local/lib/python3.9/__pycache__/abc.cpython-39.pyc'
import '_abc' # <class '_frozen_importlib.BuiltinImporter'>
import 'abc' # <_frozen_importlib_external.SourceFileLoader object at 0x7f415066b280>
import 'io' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150653f70>
# /usr/local/lib/python3.9/__pycache__/site.cpython-39.pyc matches /usr/local/lib/python3.9/site.py
# code object from '/usr/local/lib/python3.9/__pycache__/site.cpython-39.pyc'
# /usr/local/lib/python3.9/__pycache__/os.cpython-39.pyc matches /usr/local/lib/python3.9/os.py
# code object from '/usr/local/lib/python3.9/__pycache__/os.cpython-39.pyc'
# /usr/local/lib/python3.9/__pycache__/stat.cpython-39.pyc matches /usr/local/lib/python3.9/stat.py
# code object from '/usr/local/lib/python3.9/__pycache__/stat.cpython-39.pyc'
import '_stat' # <class '_frozen_importlib.BuiltinImporter'>
import 'stat' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150608af0>
# /usr/local/lib/python3.9/__pycache__/_collections_abc.cpython-39.pyc matches /usr/local/lib/python3.9/_collections_abc.py
# code object from '/usr/local/lib/python3.9/__pycache__/_collections_abc.cpython-39.pyc'
import '_collections_abc' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150608b80>
# /usr/local/lib/python3.9/__pycache__/posixpath.cpython-39.pyc matches /usr/local/lib/python3.9/posixpath.py
# code object from '/usr/local/lib/python3.9/__pycache__/posixpath.cpython-39.pyc'
# /usr/local/lib/python3.9/__pycache__/genericpath.cpython-39.pyc matches /usr/local/lib/python3.9/genericpath.py
# code object from '/usr/local/lib/python3.9/__pycache__/genericpath.cpython-39.pyc'
import 'genericpath' # <_frozen_importlib_external.SourceFileLoader object at 0x7f41506401f0>
import 'posixpath' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150608ac0>
import 'os' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150680220>
# /usr/local/lib/python3.9/__pycache__/_sitebuiltins.cpython-39.pyc matches /usr/local/lib/python3.9/_sitebuiltins.py
# code object from '/usr/local/lib/python3.9/__pycache__/_sitebuiltins.cpython-39.pyc'
import '_sitebuiltins' # <_frozen_importlib_external.SourceFileLoader object at 0x7f4150680af0>
import 'site' # <_frozen_importlib_external.SourceFileLoader object at 0x7f415066ba60>
Python 3.9.6 (default, Jul 23 2021, 14:48:54) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
import 'atexit' # <class '_frozen_importlib.BuiltinImporter'>

Answer 1

安装包时尽量明确。只需提及要安装的 Python 版本，然后安装即可。 尝试： python3.9 -m pip install library_name 您正面临这个问题，因为您有多个 python3.x 安装，所以当您尝试 python3 -m pip install library_name 时，它可能正在安装另一个 python3.x 安装的软件包。

您可以通过键入python3 --version 来检查默认的python3.x 版本，如果您不想每次都明确指定它，可以稍后在您的.bashrc 文件中更改命令python。

当我在我的系统上尝试python3.8 -v 时，我得到了相同的输出。但明确提及版本名称会有所帮助。