28.2. ensurepip
— Bootstrapping the pip
installer¶
Nuevo en la versión 3.4.
The ensurepip
package provides support for bootstrapping the pip
installer into an existing Python installation or virtual environment. This
bootstrapping approach reflects the fact that pip
is an independent
project with its own release cycle, and the latest available stable version
is bundled with maintenance and feature releases of the CPython reference
interpreter.
In most cases, end users of Python shouldn’t need to invoke this module
directly (as pip
should be bootstrapped by default), but it may be
needed if installing pip
was skipped when installing Python (or
when creating a virtual environment) or after explicitly uninstalling
pip
.
Nota
This module does not access the internet. All of the components
needed to bootstrap pip
are included as internal parts of the
package.
Ver también
- Installing Python Modules
- The end user guide for installing Python packages
- PEP 453: Explicit bootstrapping of pip in Python installations
- The original rationale and specification for this module.
28.2.1. Command line interface¶
The command line interface is invoked using the interpreter’s -m
switch.
The simplest possible invocation is:
python -m ensurepip
This invocation will install pip
if it is not already installed,
but otherwise does nothing. To ensure the installed version of pip
is at least as recent as the one bundled with ensurepip
, pass the
--upgrade
option:
python -m ensurepip --upgrade
By default, pip
is installed into the current virtual environment
(if one is active) or into the system site packages (if there is no
active virtual environment). The installation location can be controlled
through two additional command line options:
--root <dir>
: Installspip
relative to the given root directory rather than the root of the currently active virtual environment (if any) or the default root for the current Python installation.--user
: Installspip
into the user site packages directory rather than globally for the current Python installation (this option is not permitted inside an active virtual environment).
By default, the scripts pipX
and pipX.Y
will be installed (where
X.Y stands for the version of Python used to invoke ensurepip
). The
scripts installed can be controlled through two additional command line
options:
--altinstall
: if an alternate installation is requested, thepipX
script will not be installed.--default-pip
: if a «default pip» installation is requested, thepip
script will be installed in addition to the two regular scripts.
Providing both of the script selection options will trigger an exception.
28.2.2. Module API¶
ensurepip
exposes two functions for programmatic use:
-
ensurepip.
version
()¶ Returns a string specifying the bundled version of pip that will be installed when bootstrapping an environment.
-
ensurepip.
bootstrap
(root=None, upgrade=False, user=False, altinstall=False, default_pip=False, verbosity=0)¶ Bootstraps
pip
into the current or designated environment.root specifies an alternative root directory to install relative to. If root is
None
, then installation uses the default install location for the current environment.upgrade indicates whether or not to upgrade an existing installation of an earlier version of
pip
to the bundled version.user indicates whether to use the user scheme rather than installing globally.
By default, the scripts
pipX
andpipX.Y
will be installed (where X.Y stands for the current version of Python).If altinstall is set, then
pipX
will not be installed.If default_pip is set, then
pip
will be installed in addition to the two regular scripts.Setting both altinstall and default_pip will trigger
ValueError
.verbosity controls the level of output to
sys.stdout
from the bootstrapping operation.Nota
The bootstrapping process has side effects on both
sys.path
andos.environ
. Invoking the command line interface in a subprocess instead allows these side effects to be avoided.Nota
The bootstrapping process may install additional modules required by
pip
, but other software should not assume those dependencies will always be present by default (as the dependencies may be removed in a future version ofpip
).