python断网环境 离线安装第三方包，主要依赖pip的相关用法
先看pip的相应参数，命令行执行pip -h,可以看到参数很多：
方法一.在另一台电脑逐一下载相关安装包，在断网主机上依次安装相应安装包
pip download -d F:\ZK\py\whl\py387 xlrd
pip download -d F:\ZK\py\whl\py387 -i https://pypi.doubanio.com/simple/ xlwt
pip download -d F:\ZK\py\whl\py387 -i https://pypi.doubanio.com/simple/ --only-binary=:all: --python-version 38 pandas
pip install --no-index --find-links=F:\ZK\py\whl\py387\ xlrd
pip install --no-index --find-links=F:\ZK\py\whl\py387\ xlwt
pip install --no-index --find-links=F:\ZK\py\whl\py387\ pandas
pip list命令1：在默认https://pypi.org/simple位置下载xlrd库
命令2：在豆瓣下载xlwt库，速度更快
命令3：下载基于python3.8的pandas库
然后在离线主机上执行以下命令：
命令4-6：从存放了whl的文件夹中，安装相应库
命令7：查看当前安装的库
方法二.在已安装python库的电脑上生成库清单，批量下载库，在断网主机上安装相应备份
pip freeze > requirements.txt
pip download -d F:\ZK\py\whl\py387 -i https://pypi.doubanio.com/simple/ -r requirements.txt
然后在离线主机执行以下命令：
pip install --no-index --find-links=F:\ZK\py\whl\py387 -r requirement.txt方法二，更方便！
最后附上pip参数：pip -h
Usage:
pip <command> [options]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 alternate CA bundle.
--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.