Complete Guide to Installing pip for Python 3.7 on Ubuntu 18.04

Problem Background and Core Challenges

After installing Python 3.7 on Ubuntu 18.04 systems, developers frequently encounter a common issue: while pip is already installed on the system, executing python3.7 -m pip install package results in no module named pip errors. The root cause lies in pip being installed for the system's default Python version (typically Python 3.6) rather than the newly installed Python 3.7 environment.

Correct Usage of pip

To avoid version confusion issues, the best practice is to consistently use Python version-specific module execution. For Python 3.7, the proper package installation command should be:

python3.7 -m pip install package_name

This approach explicitly specifies the target Python interpreter, ensuring packages are installed into the correct environment. In contrast, directly using pip install or pip3 install commands introduces version uncertainty, potentially leading to packages being installed into incorrect Python versions.

Solutions for Installing pip for Python 3.7

When Python 3.7 lacks pip, several installation methods are available:

Method 1: Using get-pip.py Script

This is the officially recommended installation approach, utilizing Python's bootstrap script:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python3.7 get-pip.py

This script automatically downloads and installs pip compatible with Python 3.7. Note that sudo privileges may be required in some scenarios.

Method 2: Installation via Existing pip

If pip for other Python versions already exists in the system, it can be used to install pip for Python 3.7:

sudo apt install python3-pip
python3.7 -m pip install pip

This method leverages existing pip infrastructure to gradually build the target environment's package manager.

Importance of Virtual Environments

To prevent dependency conflicts between different Python versions and projects, using virtual environments is strongly recommended. Python 3.7 includes built-in venv module for creating isolated Python environments:

python3.7 -m venv my_project_env
source my_project_env/bin/activate

After activating the virtual environment, python and pip commands automatically point to executables within the environment, completely resolving version confusion issues. Virtual environments also enable independent dependency sets for each project, enhancing development maintainability.

Protecting System Python Environment

In Ubuntu systems, the native Python version is relied upon by numerous system tools and services. Therefore, system Python should not be arbitrarily modified or replaced. Using make altinstall instead of make install when compiling new Python versions prevents overwriting the system's default Python interpreter.

Alternative Tool Recommendations

For advanced users requiring multiple Python version management, consider using pyenv tool:

curl https://pyenv.run | bash

pyenv provides flexible Python version management capabilities, allowing users to easily switch between Python versions across different projects while completely avoiding interference with system Python environments.

Troubleshooting and Verification

After installation completion, verify pip is correctly installed using:

python3.7 -m pip --version

Confirm the output displays pip version corresponding to Python 3.7. If issues persist, check PATH environment variable settings to ensure Python 3.7's executable directory is in the search path.

Conclusion

Correctly installing pip for Python 3.7 requires clear target version awareness and system environment understanding. By employing specific module execution commands, creating virtual environments, and selecting appropriate installation methods, developers can effectively manage Python package dependencies while avoiding version conflict issues. These best practices apply not only to Ubuntu 18.04 but also to Python environment management on other Linux distributions.