转载请注明来源。https://www.cnblogs.com/sogeisetsu/。然后我的CSDNhttps://blog.csdn.net/suyues/article/details/103218417里也发表了这篇文章。
首先，diss一下阿里源
【原创】ubuntu18.04阿里源巨坑！安装pip3 Depends: python-pip-whl (= 8.1.1-2) but 8.1.1-2ubuntu0.4 is to be
然后，直接说处理结果
先sudo apt install python3-pip，如果不成功，换源！换成中科大源或者原始的源
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
把/etc/apt/sources.list
然后更新源sudo apt-get update，然后升级sudo apt-get upgrade。
接下来执行sudo apt install python3-pip
当时报的什么错我记不清了，大概就是没这个命令，本地没有这个包之类的。基本上用上面的方法就能解决了，如果解决不了，那就卸载掉python，重新安装吧。
更新
事情是这样的，我在执行sudo apt install python3-pip时，遇到了这样的问题：
Reading state information... Done
The following packages were automatically installed and are no longer required:
accountsservice apport-symptoms command-not-found-data cpp-5 distro-info-data gdisk iso-codes libaccountsservice0 libaio1 libdumbnet1 libevent-core-2.0-5
libisl15 libmpfr4 libreadline6 mysql-client-5.7 mysql-client-core-5.7 mysql-common mysql-server-core-5.7 python-apt-common
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
binutils binutils-common binutils-x86-64-linux-gnu build-essential cpp cpp-7 dh-python dpkg-dev fakeroot g g -7 gcc gcc-7 gcc-7-base
libalgorithm-diff-perl libalgorithm-diff-xs-perl libalgorithm-merge-perl libasan4 libatomic1 libbinutils libc-dev-bin libc6-dev libcc1-0 libcilkrts5
libdpkg-perl libexpat1-dev libfakeroot libfile-fcntllock-perl libgcc-7-dev libgomp1 libisl19 libitm1 liblsan0 libmpc3 libmpfr6 libmpx2 libpython3-dev
libpython3.6-dev libquadmath0 libstdc -7-dev libtsan0 libubsan0 linux-libc-dev manpages-dev python3 python3-asn1crypto python3-cffi-backend
python3-crypto python3-cryptography python3-dbus python3-dev python3-distutils python3-gi python3-idna python3-keyring python3-keyrings.alt
python3-lib2to3 python3-pkg-resources python3-secretstorage python3-setuptools python3-six python3-wheel python3-xdg python3.6-dev
Suggested packages:
binutils-doc cpp-doc gcc-7-locales debian-keyring g -multilib g -7-multilib gcc-7-doc libstdc 6-7-dbg gcc-multilib autoconf automake libtool flex bison
gdb gcc-doc gcc-7-multilib libgcc1-dbg libgomp1-dbg libitm1-dbg libatomic1-dbg libasan4-dbg liblsan0-dbg libtsan0-dbg libubsan0-dbg libcilkrts5-dbg
libmpx2-dbg libquadmath0-dbg glibc-doc bzr libstdc -7-doc python3-doc python3-tk python3-venv python-crypto-doc python-cryptography-doc
python3-cryptography-vectors python-dbus-doc python3-dbus-dbg gnome-keyring libkf5wallet-bin gir1.2-gnomekeyring-1.0 python-secretstorage-doc
python-setuptools-doc
E: Could not read response to hello message from hook [ ! -f /usr/bin/snap ] || /usr/bin/snap advise-snap --from-apt 2>/dev/null || true: Success
E: Could not read response to hello message from hook [ ! -f /usr/bin/snap ] || /usr/bin/snap advise-snap --from-apt 2>/dev/null || true: Success
注意这几句
The following packages were automatically installed and are no longer required:
accountsservice apport-symptoms command-not-found-data cpp-5 distro-info-data gdisk iso-codes libaccountsservice0 libaio1 libdumbnet1 libevent-core-2.0-5
libisl15 libmpfr4 libreadline6 mysql-client-5.7 mysql-client-core-5.7 mysql-common mysql-server-core-5.7 python-apt-common
Use 'apt autoremove' to remove them.
意思是有几个包是自动安装的，不需要他们了，可以用Use apt autoremoveto remove them。
剩余的几句意思是然后还会安装一些其他的包，还有几个建议安装的包，还不能从某个地方获得相应的回答（大概就是这么个意思，我英语不好，翻译做不到信达雅）
我们大体了解了出了哪些错，其实就集中在两个方面，一个是Use apt autoremoveto remove them，另一个是E: Could not read response to hello message from hook [ ! -f /usr/bin/snap ] || /usr/bin/snap advise-snap --from-apt 2>/dev/null || true: Success
解决办法是先执行apt autoremove。
然后执行sudo rm -rf /etc/apt/apt.conf.d/20snapd.conf 这个解决方法来自wsl，Ubuntu，关于解决E: Could not read response to hello message from hook [ ! -f /usr/bin/snap ] || /usr/，具体怎么个意思我也不是很明白。
然后执行apt install python3-pip就好了。