2016-06-01 18:38:18 -03:00
|
|
|
.. _tut-using:
|
2007-08-15 11:28:22 -03:00
|
|
|
|
|
|
|
****************************
|
|
|
|
Using the Python Interpreter
|
|
|
|
****************************
|
|
|
|
|
|
|
|
|
|
|
|
.. _tut-invoking:
|
|
|
|
|
|
|
|
Invoking the Interpreter
|
|
|
|
========================
|
|
|
|
|
2022-05-07 23:40:52 -03:00
|
|
|
The Python interpreter is usually installed as :file:`/usr/local/bin/python3.12`
|
2008-08-30 06:58:30 -03:00
|
|
|
on those machines where it is available; putting :file:`/usr/local/bin` in your
|
2012-09-25 08:20:29 -03:00
|
|
|
Unix shell's search path makes it possible to start it by typing the command:
|
|
|
|
|
|
|
|
.. code-block:: text
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2022-05-07 23:40:52 -03:00
|
|
|
python3.12
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2008-08-30 06:58:30 -03:00
|
|
|
to the shell. [#]_ Since the choice of the directory where the interpreter lives
|
|
|
|
is an installation option, other places are possible; check with your local
|
|
|
|
Python guru or system administrator. (E.g., :file:`/usr/local/python` is a
|
|
|
|
popular alternative location.)
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2019-11-05 09:20:38 -04:00
|
|
|
On Windows machines where you have installed Python from the :ref:`Microsoft Store
|
2022-05-07 23:40:52 -03:00
|
|
|
<windows-store>`, the :file:`python3.12` command will be available. If you have
|
2019-06-26 12:55:57 -03:00
|
|
|
the :ref:`py.exe launcher <launcher>` installed, you can use the :file:`py`
|
|
|
|
command. See :ref:`setting-envvars` for other ways to launch Python.
|
2007-08-15 11:28:22 -03:00
|
|
|
|
|
|
|
Typing an end-of-file character (:kbd:`Control-D` on Unix, :kbd:`Control-Z` on
|
|
|
|
Windows) at the primary prompt causes the interpreter to exit with a zero exit
|
|
|
|
status. If that doesn't work, you can exit the interpreter by typing the
|
Merged revisions 74779-74786,74793,74795,74811,74860-74861,74863,74876,74886,74896,74901,74903,74908,74912,74930,74933,74943,74946,74952-74955,75015,75019,75032,75068,75076,75095,75098,75102,75129,75139,75230 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r74779 | michael.foord | 2009-09-13 11:13:36 -0500 (Sun, 13 Sep 2009) | 1 line
Change to tutorial wording for reading text / binary files on Windows. Issue #6301.
........
r74780 | michael.foord | 2009-09-13 11:40:02 -0500 (Sun, 13 Sep 2009) | 1 line
Objects that compare equal automatically pass or fail assertAlmostEqual and assertNotAlmostEqual tests on unittest.TestCase. Issue 6567.
........
r74781 | michael.foord | 2009-09-13 11:46:19 -0500 (Sun, 13 Sep 2009) | 1 line
Note that sys._getframe is not guaranteed to exist in all implementations of Python, and a corresponding note in inspect.currentframe. Issue 6712.
........
r74782 | michael.foord | 2009-09-13 12:07:46 -0500 (Sun, 13 Sep 2009) | 1 line
Tutorial tweaks. Issue 6849.
........
r74783 | michael.foord | 2009-09-13 12:28:35 -0500 (Sun, 13 Sep 2009) | 1 line
unittest.TestLoader.loadTestsFromName honors the loader suiteClass attribute. Issue 6866.
........
r74784 | georg.brandl | 2009-09-13 13:15:07 -0500 (Sun, 13 Sep 2009) | 1 line
Typo fix.
........
r74785 | michael.foord | 2009-09-13 14:07:03 -0500 (Sun, 13 Sep 2009) | 1 line
Test discovery in unittest will only attempt to import modules that are importable; i.e. their names are valid Python identifiers. If an import fails during discovery this will be recorded as an error and test discovery will continue. Issue 6568.
........
r74786 | michael.foord | 2009-09-13 14:08:18 -0500 (Sun, 13 Sep 2009) | 1 line
Remove an extraneous space in unittest documentation.
........
r74793 | georg.brandl | 2009-09-14 09:50:47 -0500 (Mon, 14 Sep 2009) | 1 line
#6908: fix association of hashlib hash attributes.
........
r74795 | benjamin.peterson | 2009-09-14 22:36:26 -0500 (Mon, 14 Sep 2009) | 1 line
Py_SetPythonHome uses static storage #6913
........
r74811 | georg.brandl | 2009-09-15 15:26:59 -0500 (Tue, 15 Sep 2009) | 1 line
Add Armin Ronacher.
........
r74860 | benjamin.peterson | 2009-09-16 21:46:54 -0500 (Wed, 16 Sep 2009) | 1 line
kill bare except
........
r74861 | benjamin.peterson | 2009-09-16 22:18:28 -0500 (Wed, 16 Sep 2009) | 1 line
pep 8 defaults
........
r74863 | benjamin.peterson | 2009-09-16 22:27:33 -0500 (Wed, 16 Sep 2009) | 1 line
rationalize a bit
........
r74876 | georg.brandl | 2009-09-17 11:15:53 -0500 (Thu, 17 Sep 2009) | 1 line
#6932: remove paragraph that advises relying on __del__ being called.
........
r74886 | benjamin.peterson | 2009-09-17 16:33:46 -0500 (Thu, 17 Sep 2009) | 1 line
use macros
........
r74896 | georg.brandl | 2009-09-18 02:22:41 -0500 (Fri, 18 Sep 2009) | 1 line
#6936: for interactive use, quit() is just fine.
........
r74901 | georg.brandl | 2009-09-18 04:14:52 -0500 (Fri, 18 Sep 2009) | 1 line
#6905: use better exception messages in inspect when the argument is of the wrong type.
........
r74903 | georg.brandl | 2009-09-18 04:18:27 -0500 (Fri, 18 Sep 2009) | 1 line
#6938: "ident" is always a string, so use a format code which works.
........
r74908 | georg.brandl | 2009-09-18 08:57:11 -0500 (Fri, 18 Sep 2009) | 1 line
Use str.format() to fix beginner's mistake with %-style string formatting.
........
r74912 | georg.brandl | 2009-09-18 11:19:56 -0500 (Fri, 18 Sep 2009) | 1 line
Optimize optimization and fix method name in docstring.
........
r74930 | georg.brandl | 2009-09-18 16:21:41 -0500 (Fri, 18 Sep 2009) | 1 line
#6925: rewrite docs for locals() and vars() a bit.
........
r74933 | georg.brandl | 2009-09-18 16:35:59 -0500 (Fri, 18 Sep 2009) | 1 line
#6930: clarify description about byteorder handling in UTF decoder routines.
........
r74943 | georg.brandl | 2009-09-19 02:35:07 -0500 (Sat, 19 Sep 2009) | 1 line
#6944: the argument to PyArg_ParseTuple should be a tuple, otherwise a SystemError is set. Also clean up another usage of PyArg_ParseTuple.
........
r74946 | georg.brandl | 2009-09-19 03:43:16 -0500 (Sat, 19 Sep 2009) | 1 line
Update bug tracker reference.
........
r74952 | georg.brandl | 2009-09-19 05:42:34 -0500 (Sat, 19 Sep 2009) | 1 line
#6946: fix duplicate index entries for datetime classes.
........
r74953 | georg.brandl | 2009-09-19 07:04:16 -0500 (Sat, 19 Sep 2009) | 1 line
Fix references to threading.enumerate().
........
r74954 | georg.brandl | 2009-09-19 08:13:56 -0500 (Sat, 19 Sep 2009) | 1 line
Add Doug.
........
r74955 | georg.brandl | 2009-09-19 08:20:49 -0500 (Sat, 19 Sep 2009) | 1 line
Add Mark Summerfield.
........
r75015 | georg.brandl | 2009-09-22 05:55:08 -0500 (Tue, 22 Sep 2009) | 1 line
Fix encoding name.
........
r75019 | vinay.sajip | 2009-09-22 12:23:41 -0500 (Tue, 22 Sep 2009) | 1 line
Fixed a typo, and added sections on optimization and using arbitrary objects as messages.
........
r75032 | benjamin.peterson | 2009-09-22 17:15:28 -0500 (Tue, 22 Sep 2009) | 1 line
fix typos/rephrase
........
r75068 | benjamin.peterson | 2009-09-25 21:57:59 -0500 (Fri, 25 Sep 2009) | 1 line
comment out ugly xxx
........
r75076 | vinay.sajip | 2009-09-26 09:53:32 -0500 (Sat, 26 Sep 2009) | 1 line
Tidied up name of parameter in StreamHandler
........
r75095 | michael.foord | 2009-09-27 14:15:41 -0500 (Sun, 27 Sep 2009) | 1 line
Test creation moved from TestProgram.parseArgs to TestProgram.createTests exclusively. Issue 6956.
........
r75098 | michael.foord | 2009-09-27 15:08:23 -0500 (Sun, 27 Sep 2009) | 1 line
Documentation improvement for load_tests protocol in unittest. Issue 6515.
........
r75102 | skip.montanaro | 2009-09-27 21:12:27 -0500 (Sun, 27 Sep 2009) | 3 lines
Patch from Thomas Barr so that csv.Sniffer will set doublequote property.
Closes issue 6606.
........
r75129 | vinay.sajip | 2009-09-29 02:08:54 -0500 (Tue, 29 Sep 2009) | 1 line
Issue #7014: logging: Improved IronPython 2.6 compatibility.
........
r75139 | raymond.hettinger | 2009-09-29 13:53:24 -0500 (Tue, 29 Sep 2009) | 3 lines
Issue 7008: Better document str.title and show how to work around the apostrophe problem.
........
r75230 | benjamin.peterson | 2009-10-04 08:38:38 -0500 (Sun, 04 Oct 2009) | 1 line
test logging
........
2009-10-04 11:49:41 -03:00
|
|
|
following command: ``quit()``.
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2014-04-15 21:25:18 -03:00
|
|
|
The interpreter's line-editing features include interactive editing, history
|
2019-09-16 13:18:04 -03:00
|
|
|
substitution and code completion on systems that support the `GNU Readline
|
|
|
|
<https://tiswww.case.edu/php/chet/readline/rltop.html>`_ library.
|
|
|
|
Perhaps the quickest check to see whether command line editing is supported is
|
|
|
|
typing :kbd:`Control-P` to the first Python prompt you get. If it beeps, you
|
|
|
|
have command line editing; see Appendix :ref:`tut-interacting` for an
|
|
|
|
introduction to the keys. If nothing appears to happen, or if ``^P`` is
|
|
|
|
echoed, command line editing isn't available; you'll only be able to use
|
|
|
|
backspace to remove characters from the current line.
|
2007-08-15 11:28:22 -03:00
|
|
|
|
|
|
|
The interpreter operates somewhat like the Unix shell: when called with standard
|
|
|
|
input connected to a tty device, it reads and executes commands interactively;
|
|
|
|
when called with a file name argument or with a file as standard input, it reads
|
|
|
|
and executes a *script* from that file.
|
|
|
|
|
|
|
|
A second way of starting the interpreter is ``python -c command [arg] ...``,
|
|
|
|
which executes the statement(s) in *command*, analogous to the shell's
|
|
|
|
:option:`-c` option. Since Python statements often contain spaces or other
|
Merged revisions 63724,63726,63732,63744,63754-63755,63757-63758,63760,63775,63781-63782,63787,63805-63808,63818-63819,63823-63824 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r63724 | gregory.p.smith | 2008-05-26 22:22:14 +0200 (Mon, 26 May 2008) | 6 lines
Fixes issue2791: subprocess.Popen.communicate leaked a file descripton until
the last reference to the Popen instance was dropped. Adding explicit
close() calls fixes it.
Candidate for backport to release25-maint.
........
r63726 | benjamin.peterson | 2008-05-26 22:43:24 +0200 (Mon, 26 May 2008) | 2 lines
fix minor grammar typo
........
r63732 | benjamin.peterson | 2008-05-26 23:44:26 +0200 (Mon, 26 May 2008) | 2 lines
remove duplication in test module
........
r63744 | lars.gustaebel | 2008-05-27 14:39:23 +0200 (Tue, 27 May 2008) | 3 lines
Do not close external file objects passed to tarfile.open(mode='w:bz2')
when the TarFile is closed.
........
r63754 | benjamin.peterson | 2008-05-28 03:12:35 +0200 (Wed, 28 May 2008) | 2 lines
update tutorial function with more appropiate one from Eric Smith
........
r63755 | mark.hammond | 2008-05-28 03:54:55 +0200 (Wed, 28 May 2008) | 2 lines
bdist_wininst now works correctly when both --skip-build and --plat-name are specified.
........
r63757 | georg.brandl | 2008-05-28 13:21:39 +0200 (Wed, 28 May 2008) | 2 lines
#2989: add PyType_Modified().
........
r63758 | benjamin.peterson | 2008-05-28 13:51:41 +0200 (Wed, 28 May 2008) | 2 lines
fix spelling
........
r63760 | georg.brandl | 2008-05-28 17:41:36 +0200 (Wed, 28 May 2008) | 2 lines
#2990: prevent inconsistent state while updating method cache.
........
r63775 | georg.brandl | 2008-05-29 09:18:17 +0200 (Thu, 29 May 2008) | 2 lines
Two fixes in bytearray docs.
........
r63781 | georg.brandl | 2008-05-29 09:38:37 +0200 (Thu, 29 May 2008) | 2 lines
#2988: add note about catching CookieError when parsing untrusted cookie data.
........
r63782 | georg.brandl | 2008-05-29 09:45:26 +0200 (Thu, 29 May 2008) | 2 lines
#2985: allow i8 in XMLRPC responses.
........
r63787 | georg.brandl | 2008-05-29 16:35:39 +0200 (Thu, 29 May 2008) | 2 lines
Revert #2990 patch; it's not necessary as Armin showed.
........
r63805 | raymond.hettinger | 2008-05-30 08:37:27 +0200 (Fri, 30 May 2008) | 1 line
Issue 2784: fix leaks in exception exit.
........
r63806 | raymond.hettinger | 2008-05-30 08:49:47 +0200 (Fri, 30 May 2008) | 1 line
Issue 2855: Fix obscure crasher by slowing down the entire module. Mimics what was done to dictionaries in r59223.
........
r63807 | raymond.hettinger | 2008-05-30 09:16:53 +0200 (Fri, 30 May 2008) | 1 line
Issue 2903: Add __name__ in globals for namedtuple namespace.
........
r63808 | georg.brandl | 2008-05-30 09:54:16 +0200 (Fri, 30 May 2008) | 2 lines
#2999: fix name of third parameter in unicode.replace()'s docstring.
........
r63818 | georg.brandl | 2008-05-30 21:12:13 +0200 (Fri, 30 May 2008) | 2 lines
getloadavg() is not available on Windows.
........
r63819 | georg.brandl | 2008-05-30 21:17:29 +0200 (Fri, 30 May 2008) | 2 lines
Better quote with single quotes.
........
r63823 | benjamin.peterson | 2008-05-30 22:44:39 +0200 (Fri, 30 May 2008) | 2 lines
fix grammar
........
r63824 | marc-andre.lemburg | 2008-05-30 22:52:18 +0200 (Fri, 30 May 2008) | 5 lines
Update the locale module alias table.
Closes #3011.
........
2008-06-10 13:57:31 -03:00
|
|
|
characters that are special to the shell, it is usually advised to quote
|
|
|
|
*command* in its entirety with single quotes.
|
2007-08-15 11:28:22 -03:00
|
|
|
|
|
|
|
Some Python modules are also useful as scripts. These can be invoked using
|
|
|
|
``python -m module [arg] ...``, which executes the source file for *module* as
|
|
|
|
if you had spelled out its full name on the command line.
|
|
|
|
|
|
|
|
When a script file is used, it is sometimes useful to be able to run the script
|
|
|
|
and enter interactive mode afterwards. This can be done by passing :option:`-i`
|
2011-10-31 13:15:39 -03:00
|
|
|
before the script.
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2014-12-09 19:47:02 -04:00
|
|
|
All command line options are described in :ref:`using-on-general`.
|
|
|
|
|
2007-08-15 11:28:22 -03:00
|
|
|
|
|
|
|
.. _tut-argpassing:
|
|
|
|
|
|
|
|
Argument Passing
|
|
|
|
----------------
|
|
|
|
|
|
|
|
When known to the interpreter, the script name and additional arguments
|
2010-12-17 12:11:40 -04:00
|
|
|
thereafter are turned into a list of strings and assigned to the ``argv``
|
|
|
|
variable in the ``sys`` module. You can access this list by executing ``import
|
|
|
|
sys``. The length of the list is at least one; when no script and no arguments
|
2007-08-15 11:28:22 -03:00
|
|
|
are given, ``sys.argv[0]`` is an empty string. When the script name is given as
|
|
|
|
``'-'`` (meaning standard input), ``sys.argv[0]`` is set to ``'-'``. When
|
|
|
|
:option:`-c` *command* is used, ``sys.argv[0]`` is set to ``'-c'``. When
|
|
|
|
:option:`-m` *module* is used, ``sys.argv[0]`` is set to the full name of the
|
|
|
|
located module. Options found after :option:`-c` *command* or :option:`-m`
|
|
|
|
*module* are not consumed by the Python interpreter's option processing but
|
|
|
|
left in ``sys.argv`` for the command or module to handle.
|
|
|
|
|
|
|
|
|
|
|
|
.. _tut-interactive:
|
|
|
|
|
|
|
|
Interactive Mode
|
|
|
|
----------------
|
|
|
|
|
|
|
|
When commands are read from a tty, the interpreter is said to be in *interactive
|
|
|
|
mode*. In this mode it prompts for the next command with the *primary prompt*,
|
|
|
|
usually three greater-than signs (``>>>``); for continuation lines it prompts
|
|
|
|
with the *secondary prompt*, by default three dots (``...``). The interpreter
|
|
|
|
prints a welcome message stating its version number and a copyright notice
|
2016-07-26 06:18:21 -03:00
|
|
|
before printing the first prompt:
|
|
|
|
|
|
|
|
.. code-block:: shell-session
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2022-05-07 23:40:52 -03:00
|
|
|
$ python3.12
|
|
|
|
Python 3.12 (default, April 4 2022, 09:25:04)
|
2021-05-03 17:25:35 -03:00
|
|
|
[GCC 10.2.0] on linux
|
2007-09-28 10:13:35 -03:00
|
|
|
Type "help", "copyright", "credits" or "license" for more information.
|
2007-08-15 11:28:22 -03:00
|
|
|
>>>
|
|
|
|
|
2009-09-18 04:27:51 -03:00
|
|
|
.. XXX update for new releases
|
2007-09-28 10:13:35 -03:00
|
|
|
|
2007-08-15 11:28:22 -03:00
|
|
|
Continuation lines are needed when entering a multi-line construct. As an
|
|
|
|
example, take a look at this :keyword:`if` statement::
|
|
|
|
|
2014-03-28 20:39:25 -03:00
|
|
|
>>> the_world_is_flat = True
|
2007-08-15 11:28:22 -03:00
|
|
|
>>> if the_world_is_flat:
|
2007-09-04 04:15:32 -03:00
|
|
|
... print("Be careful not to fall off!")
|
2009-01-03 17:18:54 -04:00
|
|
|
...
|
2007-08-15 11:28:22 -03:00
|
|
|
Be careful not to fall off!
|
|
|
|
|
|
|
|
|
2014-09-18 10:30:28 -03:00
|
|
|
For more on interactive mode, see :ref:`tut-interac`.
|
|
|
|
|
|
|
|
|
2007-08-15 11:28:22 -03:00
|
|
|
.. _tut-interp:
|
|
|
|
|
|
|
|
The Interpreter and Its Environment
|
|
|
|
===================================
|
|
|
|
|
|
|
|
|
2011-06-11 05:34:19 -03:00
|
|
|
.. _tut-source-encoding:
|
|
|
|
|
2007-08-15 11:28:22 -03:00
|
|
|
Source Code Encoding
|
|
|
|
--------------------
|
|
|
|
|
2007-09-28 10:13:35 -03:00
|
|
|
By default, Python source files are treated as encoded in UTF-8. In that
|
|
|
|
encoding, characters of most languages in the world can be used simultaneously
|
|
|
|
in string literals, identifiers and comments --- although the standard library
|
|
|
|
only uses ASCII characters for identifiers, a convention that any portable code
|
|
|
|
should follow. To display all these characters properly, your editor must
|
|
|
|
recognize that the file is UTF-8, and it must use a font that supports all the
|
|
|
|
characters in the file.
|
2007-09-04 04:15:32 -03:00
|
|
|
|
2017-02-02 00:55:47 -04:00
|
|
|
To declare an encoding other than the default one, a special comment line
|
|
|
|
should be added as the *first* line of the file. The syntax is as follows::
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2009-01-03 17:18:54 -04:00
|
|
|
# -*- coding: encoding -*-
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2017-02-02 00:55:47 -04:00
|
|
|
where *encoding* is one of the valid :mod:`codecs` supported by Python.
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2017-02-02 00:55:47 -04:00
|
|
|
For example, to declare that Windows-1252 encoding is to be used, the first
|
|
|
|
line of your source code file should be::
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2018-05-09 05:10:55 -03:00
|
|
|
# -*- coding: cp1252 -*-
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2017-02-02 00:55:47 -04:00
|
|
|
One exception to the *first line* rule is when the source code starts with a
|
|
|
|
:ref:`UNIX "shebang" line <tut-scripts>`. In this case, the encoding
|
|
|
|
declaration should be added as the second line of the file. For example::
|
2007-08-15 11:28:22 -03:00
|
|
|
|
2017-02-02 00:55:47 -04:00
|
|
|
#!/usr/bin/env python3
|
2018-05-09 05:10:55 -03:00
|
|
|
# -*- coding: cp1252 -*-
|
2007-08-15 11:28:22 -03:00
|
|
|
|
|
|
|
.. rubric:: Footnotes
|
|
|
|
|
2009-09-18 04:27:51 -03:00
|
|
|
.. [#] On Unix, the Python 3.x interpreter is by default not installed with the
|
2008-08-30 06:58:30 -03:00
|
|
|
executable named ``python``, so that it does not conflict with a
|
|
|
|
simultaneously installed Python 2.x executable.
|