如何使用pip更新/升级软件包？

What is the way to update a package using pip? those do not work:

pip update
pip upgrade

I know this is a simple question but it is needed as it is not so easy to find (pip documentation doesn’t pop up and other questions from stack overflow are relevant but are not exactly about that)

The way is

pip install [package_name] --upgrade

or in short

pip install [package_name] -U

Using sudo will ask to enter your root password to confirm the action, but although common, is considered unsafe.

If you do not have a root password (if you are not the admin) you should probably work with virtualenv.

You can also use the user flag to install it on this user only.

pip install [package_name] --upgrade --user

For a non-specific package and a more general solution you can check out pip-review, a tool that checks what packages could/should be updated.

$ pip-review --interactive
requests==0.14.0 is available (you have 0.13.2)
Upgrade now? [Y]es, [N]o, [A]ll, [Q]uit y

tl;dr script to update all installed packages

If you only want to upgrade one package, refer to @borgr’s answer. I often find it necessary, or at least pleasing, to upgrade all my packages at once. Currently, pip doesn’t natively support that action, but with sh scripting it is simple enough. You use pip list, awk (or cut and tail), and command substitution. My normal one-liner is:

for i in $(pip list -o | awk 'NR > 2 {print $1}'); do sudo pip install -U $i; done

This will ask for the root password. If you do not have access to that, the option of pip or virtualenv may be something to look into.

import subprocess as sbp
import pip
pkgs = eval(str(sbp.run("pip3 list -o --format=json", shell=True,
                         stdout=sbp.PIPE).stdout, encoding='utf-8'))
for pkg in pkgs:
    sbp.run("pip3 install --upgrade " + pkg['name'], shell=True)

Save as xx.py
Then run Python3 xx.py
Environment: python3.5+ pip10.0+

To upgrade pip for Python3.4+, you must use pip3 as follows:

sudo pip3 install pip --upgrade

This will upgrade pip located at: /usr/local/lib/python3.X/dist-packages

Otherwise, to upgrade pip for Python2.7, you would use pip as follows:

sudo pip install pip --upgrade

This will upgrade pip located at: /usr/local/lib/python2.7/dist-packages