Python: virtualenv Tutorial

By Xah Lee. Date: . Last updated: .

virtualenv is a tool to create isolated Python environments, so you can install different version of python and different versions of library.

◆ virtualenv
You must provide a DEST_DIR
Usage: virtualenv [OPTIONS] DEST_DIR

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -v, --verbose         Increase verbosity.
  -q, --quiet           Decrease verbosity.
  -p PYTHON_EXE, --python=PYTHON_EXE
                        The Python interpreter to use, e.g., --python=python2.5 will use the
                        python2.5 interpreter to create the new environment.  The default is the
                        interpreter that virtualenv was installed with (/usr/bin/python)
  --clear               Clear out the non-root install and start from scratch.
  --no-site-packages    DEPRECATED. Retained only for backward compatibility. Not having access to
                        global site-packages is now the default behavior.
  --system-site-packages
                        Give the virtual environment access to the global site-packages.
  --always-copy         Always copy files rather than symlinking.
  --unzip-setuptools    Unzip Setuptools when installing it.
  --relocatable         Make an EXISTING virtualenv environment relocatable. This fixes up scripts
                        and makes all .pth files relative.
  --no-setuptools       Do not install setuptools (or pip) in the new virtualenv.
  --no-pip              Do not install pip in the new virtualenv.
  --extra-search-dir=DIR
                        Directory to look for setuptools/pip distributions in. This option can be
                        used multiple times.
  --never-download      DEPRECATED. Retained only for backward compatibility. This option has no
                        effect. Virtualenv never downloads pip or setuptools.
  --prompt=PROMPT       Provides an alternative prompt prefix for this environment.
  --setuptools          DEPRECATED. Retained only for backward compatibility. This option has no
                        effect.
  --distribute          DEPRECATED. Retained only for backward compatibility. This option has no
                        effect.

see also Python: What's PyPi, pip, easy_install, setuptools?

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Python 3

Lang Detail

  1. Print Version String
  2. Quoting String
  3. String Operations
  4. Format String
  5. Operators
  6. Object, ID, Type

Misc

  1. Traverse Directory
  2. Sort List, Matrix, Object
  3. Python 3: Map with Side Effect Doesn't Work If Result is Not Used
  4. Python 3 Closure
  5. Python 2 and 3 Difference