How to use the pip command for a detailed explanation of the installation method that Python developers must read

Must-see for Python developers: Detailed explanation of pip command installation method

Introduction:
Python is a widely used high-level programming language with a large number of developers Communities and ecosystems. In order to facilitate Python developers to manage and use third-party libraries, Python provides a powerful package management tool-pip. This article will explain the installation method of pip in detail and provide specific code examples to help readers better use pip to install packages.

1. What is pip
Pip is a Python package management tool that can be used to install, upgrade, uninstall and manage Python packages. It is part of the Python Package Index (PyPI), a repository that stores a large number of Python packages. pip enables Python developers to easily search, install and manage these packages, thereby improving development efficiency.

2. How to install pip

1. In Python 2.7.9 or later, pip is already built-in. You can check whether pip has been installed by running the following command:

   $ pip --version

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   If it is installed, the version number of pip will be displayed; if it is not installed, it will prompt that the command is not found.

2. If the Python version is lower than 2.7.9 or pip is not installed, you can use the following method to install pip.

a) Install using a script
Python provides a script to install pip. You can download the get-pip.py script from https://bootstrap.pypa.io/get-pip.py and execute the following command to install pip:

$ python get-pip.py

b) Use the system package manager to install
In some operating systems, pip can be installed directly through the system package manager. For example, in Debian/Ubuntu system, you can use the following command to install pip:

$ sudo apt-get install python-pip

c) Use the ensurepip module that comes with Python to install
In Python3.4 or higher, Python comes with A module named ensurepip has been created, which can be used to install pip. You can use the following command to install pip:

$ python -m ensurepip --upgrade

This command will check and install pip. If it is already installed, it will automatically upgrade to the latest version.

3. Common commands of pip

1. Installation package
   It is very simple to use pip to install the package. You only need to use the install command and add the required Just install the package name. For example, to install a package named requests:

   $ pip install requests

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2. Upgrade package
   Use the install command plus --upgrade option can upgrade installed packages. For example, to upgrade a package named requests:

   $ pip install --upgrade requests

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3. Uninstall package
   Use the uninstall command plus the name of the package to be uninstalled. Uninstall the installed package. For example, to uninstall a package named requests:

   $ pip uninstall requests

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4. View installed packages
   Use the freeze command to view installed packages Package and its version number. For example:

   $ pip freeze

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   Executing this command will list all installed packages and display them in the form package name==version number.

4. Advanced usage of pip

1. Install the specified version of the package
   By adding == after the package name and version number, you can install the specified version of the package. For example, to install version 2.18.4 named requests:

   $ pip install requests==2.18.4

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2. Install a specific version range of the package
   by appending after the package name Symbols such as >=, <= can install the latest version within a specific version range of the package. For example, to install the 2.x version named requests:

   $ pip install requests>=2.0.0,<=2.99.99

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3. Install the package from the requirements.txt file
   requirements.txt It is a text file used to record the packages and their version numbers that the project depends on. You can install the package from the requirements.txt file through the following command:

   $ pip install -r requirements.txt

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5. Conclusion

This article introduces the pip installation method in detail, and Specific code examples are provided. As an essential tool for Python developers, pip can help developers manage and use third-party libraries. By learning and mastering the usage of pip, developers can develop Python more efficiently and conveniently.

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