当使用Python进行开发时，pip是一个非常有用的包管理工具，它可以帮助我们方便地安装、升级和管理Python包。本文将介绍一些常用的pip命令，以帮助您更好地使用pip。
- 查看帮助文档
运行pip --help运行这个命令将帮助我们更好地了解pip的使用，pip命令的参数会完整展示出来，如下：
pip --help
Usage:
pip <command> [options]
Commands:
install Install packages.
download Download packages.
uninstall Uninstall packages.
freeze Output installed packages in requirements format.
inspect Inspect the python environment.
list List installed packages.
show Show information about installed packages.
check Verify installed packages have compatible dependencies.
config Manage local and global configuration.
search Search PyPI for packages.
cache Inspect and manage pip's wheel cache.
index Inspect information available from package indexes.
wheel Build wheels from your requirements.
hash Compute hashes of package archives.
completion A helper command used for command completion.
debug Show information useful for debugging.
help Show help for commands.
General Options:
-h, --help Show help.
--debug Let unhandled exceptions propagate outside the main subroutine, instead of logging them
to stderr.
--isolated Run pip in an isolated mode, ignoring environment variables and user configuration.
--require-virtualenv Allow pip to only run in a virtual environment; exit with an error otherwise.
-v, --verbose Give more output. Option is additive, and can be used up to 3 times.
-V, --version Show version and exit.
-q, --quiet Give less output. Option is additive, and can be used up to 3 times (corresponding to
WARNING, ERROR, and CRITICAL logging levels).
--log <path> Path to a verbose appending log.
--no-input Disable prompting for input.
--proxy <proxy> Specify a proxy in the form scheme://[user:passwd@]proxy.server:port.
--retries <retries> Maximum number of retries each connection should attempt (default 5 times).
--timeout <sec> Set the socket timeout (default 15 seconds).
--exists-action <action> Default action when a path already exists: (s)witch, (i)gnore, (w)ipe, (b)ackup,
(a)bort.
--trusted-host <hostname> Mark this host or host:port pair as trusted, even though it does not have valid or any
HTTPS.
--cert <path> Path to PEM-encoded CA certificate bundle. If provided, overrides the default. See 'SSL
Certificate Verification' in pip documentation for more information.
--client-cert <path> Path to SSL client certificate, a single file containing the private key and the
certificate in PEM format.
--cache-dir <dir> Store the cache data in <dir>.
--no-cache-dir Disable the cache.
--disable-pip-version-check
Don't periodically check PyPI to determine whether a new version of pip is available for
download. Implied with --no-index.
--no-color Suppress colored output.
--no-python-version-warning
Silence deprecation warnings for upcoming unsupported Pythons.
--use-feature <feature> Enable new functionality, that may be backward incompatible.
--use-deprecated <feature> Enable deprecated functionality, that will be removed in the future.- 查看版本
pip --version # python2.x命令
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pip3 --version # python3.x命令- 升级pip版本
我们在安装第三方库时，有时会提醒我们要对pip进行更新，下面的命令就可以升级pip命令，命令如下：
pip install -U pip- 查看已经安装的库
pip list
# 查找某个具体的库
pip list | grep 库名 # mac系统或者Linux系统
pip list | findstr 库名 # Windows系统安装第三方库
安装第三方库需要运行pip install 这一条命令，下面是安装库名的几条具体命令：
pip install [options] <requirement specifier> [package-index-options] ...
pip install [options] -r <requirements file> [package-index-options] ...
pip install [options] [-e] <vcs project url> ...
pip install [options] [-e] <local project path> ...
pip install [options] <archive url/path> ...直接安装
直接运行pip install [options] [package-index-options] 这一条命令，即可安装自己想要的库，示例如下：
pip install selenium指定版本安装
有时候我们需要指定安装库的版本，所以我们就需要在命令中加上版本限制
pip install package # 默认安装最新版本
pip install package==3.141.0 # 指定版本
pip install package>=3.141.0 # 最小版本指定源安装
pip默认是使用https://pypi.python.org/simple这个官方源地址，但是这个源安装库可能会比较慢，所以我们可以指定境内源进行安装，加快速度，常用的境内源地址如下：
清华：https://pypi.tuna.tsinghua.edu.cn/simple
阿里云：http://mirrors.aliyun.com/pypi/simple/
中国科技大学 https://pypi.mirrors.ustc.edu.cn/simple/
山东理工大学：http://pypi.sdutlinux.org/
豆瓣：http://pypi.douban.com/simple/安装命令如下：
pip install -i https://pypi.douban.com/simple/ package通过 requirements 文件批量安装第三方库
我们从GitHub等仓库中拉取代码之后，需要在本地运行项目时，如果项目带有requirements文件，我们只需要通过这个文件就可以一次性安装这个项目所需要的第三方库了。
pip install [options] -r [package-index-options]示例如下：
pip install -r requirements.txt下载包但不安装
pip install <包名> -d <目录>
pip install -d <目录> -r requirements.txt卸载包
pip uninstall package
pip uninstall -r requirements.txt更新包
pip install --upgrade package
pip install -U package # --upgrade 可简写为 -U显示包所在的目录
pip show -f <包名>查询可升级的包
pip list --outdated # 列出所有过期的库
pip list -o # --outdated的简写，列出所有过期的库卸载 pip
python -m pip uninstall pip