What is the purpose of "pip install --user ..."?

User Site Directory: What, Where, How

Let's break down the concept of user site directory:

• It's your personal space for Python packages, isolated from the system-wide package neighborhood.

• Using the --user flag, pip sets up camp here to install packages.

• To find the directory, like asking for an address, execute:

  python -m site --user-base # "...and you are? Oh, here's your user site directory."
  

  This command will guide you home.

• Now, any scripts from your user-installed packages wish to be available from the terminal. To fulfill their wish, add the user's Python script directory (usually ~/.local/bin) to your PATH. Think of it as a fast-pass for scripts to the terminal amusement park.

• A word of caution: Avoid mixing --user installs with virtual environments. They are like oil and water.

Remember: Virtual environments handle package isolation on their own. Inviting --user installs to the party may lead to a messy aftermath (read: conflicts and unpredictable environments).

User-Based Install — Your Ally in Different Scenarios

Shared or Multi-User Systems

Got a family of Python users sharing the same system? Fret not! The --user flag installs packages “quietly” in your separate user space. So, go ahead, experiment — your packages won't cross paths with other users' packages, promise!

Personal Playground

Playing in the sandbox, testing out new packages, running short-term experiments — do whatever you want! Keep your system Python clean and install your packages with --user! They'll rest in your user site directory, away from the system's critical components.

Restricted Systems

Locked out from making system-wide changes by sudo? Can't touch system-wide Python environment? Well, --user is your knight in shining armour to install Python packages independently of the admin.

Cases When '--user' Isn't This Charming

pip install --user is a handy tool, but there are situations where it may not be the best choice:

• Within virtual environments. They've got their isolation mechanisms.
• When you want to install Python packages system-wide. Here, it's best to use your system's package manager (apt on Debian/ubuntu).
• If a system-wide application/service feels possessive over a specific version of a package. Stick to the system-wide installations and keep --user out of the mix.

Savvy Tips and Pitfalls with --user

Clever Workarounds

Navigate the pip install --user landscape better by:

• Dodging the sudo pip install --user pit. It's like trying to whisper loudly — just don't do it.
• Ensuring ~/.local/bin is included in your PATH if executables from user-installed packages are playing hide-and-seek in the terminal.
• Keeping environment variables in check. They can unintentionally meddle with your --user installations (the usual suspect: PYTHONPATH).

Maximize --user Usage

Unleash the true power of --user:

• Use it for rapid tests or package trials — like a trial room for packages.
• Run pip list --user to keep an eye on your user-installed packages — feel like an overseer.
• Let your IDEs in on the user site directory secret for seamless project setups.

Cleaning Up

Stay tidy by:

• Cleaning your room — ahem, the user site directory — from time-to-time to discard redundant packages.
• Revisiting your PATH and cleaning up any unnecessary updates to maintain clarity and order.