Creation of
虚拟环境
is done by executing the
pyvenv
script:
pyvenv /path/to/new/virtual/environment
Running this command creates the target directory (creating any parent directories that don’t exist already) and places a
pyvenv.cfg
file in it with a
home
key pointing to the Python installation the command was run from. It also creates a
bin
(或
Scripts
on Windows) subdirectory containing a copy of the
python
binary (or binaries, in the case of Windows). It also creates an (initially empty)
lib/pythonX.Y/site-packages
subdirectory (on Windows, this is
Lib\site-packages
).
另请参阅
On Windows, you may have to invoke the
pyvenv
script as follows, if you don’t have the relevant PATH and PATHEXT settings:
c:\Temp>c:\Python34\python c:\Python34\Tools\Scripts\pyvenv.py myenv
or equivalently:
c:\Temp>c:\Python34\python -m venv myenv
The command, if run with
-h
, will show the available options:
usage: venv [-h] [--system-site-packages] [--symlinks] [--clear]
[--upgrade] [--without-pip] ENV_DIR [ENV_DIR ...]
Creates virtual Python environments in one or more target directories.
positional arguments:
ENV_DIR A directory to create the environment in.
optional arguments:
-h, --help show this help message and exit
--system-site-packages Give access to the global site-packages dir to the
virtual environment.
--symlinks Try to use symlinks rather than copies, when symlinks
are not the default for the platform.
--copies Try to use copies rather than symlinks, even when
symlinks are the default for the platform.
--clear Delete the environment directory if it already exists.
If not specified and the directory exists, an error is
raised.
--upgrade Upgrade the environment directory to use this version
of Python, assuming Python has been upgraded in-place.
--without-pip Skips installing or upgrading pip in the virtual
environment (pip is bootstrapped by default)
Depending on how the
venv
functionality has been invoked, the usage message may vary slightly, e.g. referencing
pyvenv
而不是
venv
.
3.4 版改变：
Installs pip by default, added the
--without-pip
and
--copies
选项
3.4 版改变：
In earlier versions, if the target directory already existed, an error was raised, unless the
--clear
or
--upgrade
option was provided. Now, if an existing directory is specified, its contents are removed and the directory is processed as if it had been newly created.
The created
pyvenv.cfg
file also includes the
include-system-site-packages
key, set to
true
if
venv
is run with the
--system-site-packages
option,
false
否则。
除非
--without-pip
option is given,
ensurepip
will be invoked to bootstrap
pip
into the virtual environment.
Multiple paths can be given to
pyvenv
, in which case an identical virtualenv will be created, according to the given options, at each provided path.
Once a venv has been created, it can be “activated” using a script in the venv’s binary directory. The invocation of the script is platform-specific:
| 平台 | Shell | Command to activate virtual environment |
|---|---|---|
| Posix | bash/zsh | $ source <venv>/bin/activate |
| fish | $ . <venv>/bin/activate.fish | |
| csh/tcsh | $ source <venv>/bin/activate.csh | |
| Windows | cmd.exe | C:> <venv>/Scripts/activate.bat |
| PowerShell | PS C:> <venv>/Scripts/Activate.ps1 |
You don’t specifically need to activate an environment; activation just prepends the venv’s binary directory to your path, so that “python” invokes the venv’s Python interpreter and you can run installed scripts without having to use their full path. However, all scripts installed in a venv should be runnable without activating it, and run with the venv’s Python automatically.
You can deactivate a venv by typing “deactivate” in your shell. The exact mechanism is platform-specific: for example, the Bash activation script defines a “deactivate” function, whereas on Windows there are separate scripts called
deactivate.bat
and
Deactivate.ps1
which are installed when the venv is created.
3.4 版新增：
fish
and
csh
activation scripts.