現在下載的Python 3，都會內建PyPi，方便安裝一些需要用到的模組。

用法：

pip <command> [options]

command和options裡有很多命令，常用的還是install、uninstall

Install

install顧名思義就是安裝模組，以下面的例子來說明使用方法。

• 如果需要安裝numpy的話，可以用以下的命令進行安裝：

pip install numpy

• 如果需要安裝numpy的話，並需要指定的版本1.18.2，可以用以下的命令進行安裝：

pip install numpy==1.18.2

• 如果需要通過文字檔案來安裝模組，可以用以下的命令進行安裝：

pip install -r requirements.txt

requirements.txt中的內容可以是如下資訊：

這些資訊可以通過以下命令進行生成：

pip freeze > requirements.txt

Uninstall

uninstall則是解除安裝模組，同樣以例子來說明使用方法。

如果要解除安裝numpy的話，可以用以下命令進行解除安裝：

pip uninstall numpy

全部commands和options的命令

Commands:
  install                     Install packages.
  download                    Download packages.
  uninstall                   Uninstall packages.
  freeze                      Output installed packages 
 
in requirements format.
  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.
  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.
  --isolated                  Run pip in an isolated mode, ignoring environment variables and user configuration.
  -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 [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.