chins-MBP:~ chinvincent$ pip list
Package                                Version
-------------------------------------- --------
altgraph                               0.10.2
backports-abc                          0.5
bdist-mpkg                             0.5.0
bonjour-py                             0.3
click                                  6.7
distribute                             0.7.3
Flask                                  1.0.2
futures                                3.2.0
itsdangerous                           0.24
Jinja2                                 2.10
macholib                               1.5.1
MarkupSafe                             1.0
matplotlib                             1.3.1
modulegraph                            0.10.4
nose                                   1.3.7
numpy                                  1.8.0rc1
pip                                    10.0.1
py2app                                 0.7.3
pyobjc-core                            2.5.1
pyobjc-framework-Accounts              2.5.1
pyobjc-framework-AddressBook           2.5.1
pyobjc-framework-AppleScriptKit        2.5.1
pyobjc-framework-AppleScriptObjC       2.5.1
pyobjc-framework-Automator             2.5.1
pyobjc-framework-CFNetwork             2.5.1
pyobjc-framework-Cocoa                 2.5.1
pyobjc-framework-Collaboration         2.5.1
pyobjc-framework-CoreData              2.5.1
pyobjc-framework-CoreLocation          2.5.1
pyobjc-framework-CoreText              2.5.1
pyobjc-framework-DictionaryServices    2.5.1
pyobjc-framework-EventKit              2.5.1
pyobjc-framework-ExceptionHandling     2.5.1
pyobjc-framework-FSEvents              2.5.1
pyobjc-framework-InputMethodKit        2.5.1
pyobjc-framework-InstallerPlugins      2.5.1
pyobjc-framework-InstantMessage        2.5.1
pyobjc-framework-LatentSemanticMapping 2.5.1
pyobjc-framework-LaunchServices        2.5.1
pyobjc-framework-Message               2.5.1
pyobjc-framework-OpenDirectory         2.5.1
pyobjc-framework-PreferencePanes       2.5.1
pyobjc-framework-PubSub                2.5.1
pyobjc-framework-QTKit                 2.5.1
pyobjc-framework-Quartz                2.5.1
pyobjc-framework-ScreenSaver           2.5.1
pyobjc-framework-ScriptingBridge       2.5.1
pyobjc-framework-SearchKit             2.5.1
pyobjc-framework-ServiceManagement     2.5.1
pyobjc-framework-Social                2.5.1
pyobjc-framework-SyncServices          2.5.1
pyobjc-framework-SystemConfiguration   2.5.1
pyobjc-framework-WebKit                2.5.1
pyOpenSSL                              0.13.1
pyparsing                              2.0.1
python-dateutil                        1.5
pytz                                   2013.7
scipy                                  0.13.0b1
setuptools                             18.5
singledispatch                         3.4.0.3
six                                    1.4.1
tornado                                5.0.2
Werkzeug                               0.14.1
xattr                                  0.6.4
zope.interface                         4.1.1
chins-MBP:~ chinvincent$ sudo pip install requests
The directory '/Users/chinvincent/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/Users/chinvincent/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Requirement already satisfied: requests in ./Library/Python/2.7/lib/python/site-packages (2.18.4)
Requirement already satisfied: idna<2.7,>=2.5 in ./Library/Python/2.7/lib/python/site-packages (from requests) (2.6)
Requirement already satisfied: urllib3<1.23,>=1.21.1 in ./Library/Python/2.7/lib/python/site-packages (from requests) (1.22)
Requirement already satisfied: certifi>=2017.4.17 in ./Library/Python/2.7/lib/python/site-packages (from requests) (2018.4.16)
Requirement already satisfied: chardet<3.1.0,>=3.0.2 in ./Library/Python/2.7/lib/python/site-packages (from requests) (3.0.4)

我安裝包明明已經(jīng)安裝，但是pip list 為啥總是沒有呢？不知道原因 困惑很久，求人指導(dǎo)！