ensurepip
— 自引导
pip
安装程序
¶
3.4 版新增。
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
.
注意
This module
does not
access the internet. All of the components needed to bootstrap
pip
are included as internal parts of the package.
另请参阅
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
默认情况下，
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>
: Installs
pip
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
: Installs
pip
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, the
pipX
script will
not
be installed.
--default-pip
: if a “default pip” installation is requested, the
pip
script will be installed in addition to the two regular scripts.
Providing both of the script selection options will trigger an exception.
Changed in version 3.6.3: The exit status is non-zero if the command fails.
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
and
pipX.Y
will be installed (where X.Y stands for the current version of Python).
若
altinstall
is set, then
pipX
will
not
be installed.
若
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.
注意
The bootstrapping process has side effects on both
sys.path
and
os.environ
. Invoking the command line interface in a subprocess instead allows these side effects to be avoided.
注意
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 of
pip
).