PYTHON(10 April, 1998) UNIX System V PYTHON(10 April, 1998)
NAME
python - an interpreted, interactive, object-oriented
programming language
SYNOPSIS
python [ -d ] [ -i ] [ -O ] [ -S ] [ -t ] [ -u ] [ -v ] [ -x
] [ -X ]
[ -c command | script | - ] [ arguments ]
DESCRIPTION
Python is an interpreted, interactive, object-oriented
programming language that combines remarkable power with
very clear syntax. For an introduction to programming in
Python you are referred to the Python Tutorial. The Python
Library Reference documents built-in and standard types,
constants, functions and modules. Finally, the Python
Reference Manual describes the syntax and semantics of the
core language in (perhaps too) much detail.
Python's basic power can be extended with your own modules
written in C or C++. On most systems such modules may be
dynamically loaded. Python is also adaptable as an
extension language for existing applications. See the
internal documentation for hints.
COMMAND LINE OPTIONS
-d Turn on parser debugging output (for wizards only,
depending on compilation options).
-i When a script is passed as first argument or the -c
option is used, enter interactive mode after executing
the script or the command. It does not read the
$PYTHONSTARTUP file. This can be useful to inspect
global variables or a stack trace when a script raises
an exception.
-O Turn on basic optimizations. This changes the filename
extension for compiled (bytecode) files from .pyc to
pyo.
-S Disable the import of the module site and the site-
dependent manipulations of sys.path that it entails.
-t Issue a warning when a source file mixes tabs and
spaces for indentation in a way that makes it depend on
the worth of a tab expressed in spaces. Issue an error
when the option is given twice.
-u Force stdin, stdout and stderr to be totally
unbuffered.
-v Print a message each time a module is initialized,
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showing the place (filename or built-in module) from
which it is loaded.
-x Skip the first line of the source. This is intended
for a DOS specific hack only. Warning: the line
numbers in error messages will be off by one!
-X Make the standard exceptions strings instead of
classes. Use for backward compatibility with old code
only.
-c command
Specify the command to execute (see next section).
This terminates the option list (following options are
passed as arguments to the command).
INTERPRETER INTERFACE
The interpreter interface resembles that of the UNIX shell:
when called with standard input connected to a tty device,
it prompts for commands and executes them until an EOF is
read; when called with a file name argument or with a file
as standard input, it reads and executes a script from that
file; when called with -c command, it executes the Python
statement(s) given as command. Here command may contain
multiple statements separated by newlines. Leading
whitespace is significant in Python statements! In non-
interactive mode, the entire input is parsed befored it is
executed.
If available, the script name and additional arguments
thereafter are passed to the script in the Python variable
sys.argv , which is a list of strings (you must first import
sys to be able to access it). If no script name is given,
sys.argv is empty; if -c is used, sys.argv[0] contains the
string '-c'. Note that options interpreted by the Python
interpreter itself are not placed in sys.argv.
In interactive mode, the primary prompt is `>>>'; the second
prompt (which appears when a command is not complete) is
`...'. The prompts can be changed by assignment to sys.ps1
or sys.ps2. The interpreter quits when it reads an EOF at a
prompt. When an unhandled exception occurs, a stack trace
is printed and control returns to the primary prompt; in
non-interactive mode, the interpreter exits after printing
the stack trace. The interrupt signal raises the Keyboard-
Interrupt exception; other UNIX signals are not caught
(except that SIGPIPE is sometimes ignored, in favor of the
IOError exception). Error messages are written to stderr.
FILES AND DIRECTORIES
These are subject to difference depending on local
installation conventions:
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/usr/local/bin/python
Recommended location of the interpreter.
/usr/local/lib/python<version>
Recommended location of the directory containing the
standard modules.
ENVIRONMENT VARIABLES
PYTHONHOME
Change the location of the standard Python libraries.
By default, the libraries are searched in
<prefix>/lib/python<version> and
<exec_prefix>/lib/python<version>, where <prefix> and
<exec_prefix> are installation-dependent directories,
both defaulting to /usr/local. When $PYTHONHOME is set
to a single directory, its value replaces both <prefix>
and <exec_prefix>. To specify different values for
these, set $PYTHONHOME to <prefix>:<exec_prefix>.
PYTHONPATH
Augments the default search path for module files. The
format is the same as the shell's $PATH: one or more
directory pathnames separated by colons. Non-existant
directories are silently ignored. The default search
path is installation dependent, but generally begins
with <prefix>/lib/python<version> (see PYTHONHOME
below). The default search path is always appended to
$PYTHONPATH. If a script argument is given, the
directory containing the script is inserted in the path
in front of $PYTHONPATH. The search path can be
manipulated from within a Python program as the
variable sys.path .
PYTHONSTARTUP
If this is the name of a readable file, the Python
commands in that file are executed before the first
prompt is displayed in interactive mode. The file is
executed in the same name space where interactive
commands are executed so that objects defined or
imported in it can be used without qualification in the
interactive session. You can also change the prompts
sys.ps1 and sys.ps2 in this file.
PYTHONDEBUG
If this is set to a non-empty string it is equivalent
to specifying the -d option.
PYTHONINSPECT
If this is set to a non-empty string it is equivalent
to specifying the -i option.
PYTHONUNBUFFERED
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If this is set to a non-empty string it is equivalent
to specifying the -u option.
PYTHONVERBOSE
If this is set to a non-empty string it is equivalent
to specifying the -v option.
SEE ALSO
Python Tutorial
Python Library Reference
Python Reference Manual
AUTHOR
Guido van Rossum
CNRI
1895 Preston White Drive
Reston, VA 20191
USA
E-mail: guido@cnri.reston.va.us, guido@python.org
And a cast of thousands.
INTERNET RESOURCES
Web site: http://www.python.org
FTP site: ftp://ftp.python.org
Newsgroup: comp.lang.python
COPYRIGHT
Copyright 1991-1995 by Stichting Mathematisch Centrum,
Amsterdam, The Netherlands.
All Rights Reserved
Permission to use, copy, modify, and distribute this
software and its documentation for any purpose and without
fee is hereby granted, provided that the above copyright
notice appear in all copies and that both that copyright
notice and this permission notice appear in supporting
documentation, and that the names of Stichting Mathematisch
Centrum or CWI or Corporation for National Research
Initiatives or CNRI not be used in advertising or publicity
pertaining to distribution of the software without specific,
written prior permission.
While CWI is the initial source for this software, a
modified version is made available by the Corporation for
National Research Initiatives (CNRI) at the Internet address
ftp://ftp.python.org.
STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
EVENT SHALL STICHTING MATHEMATISCH CENTRUM OR CNRI BE LIABLE
FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH
THE USE OR PERFORMANCE OF THIS SOFTWARE.
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