PYTHON(1)						      General Commands Manual							 PYTHON(1)

NAME

       python - an interpreted, interactive, object-oriented programming language

SYNOPSIS

       python [ -d ] [ -E ] [ -h ] [ -i ] [ -m module-name ] [ -O ]
	      [ -Q argument ] [ -S ] [ -t ] [ -u ]
	      [ -v ] [ -V ] [ -W argument ] [ -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  stan-
       dard types, constants, functions and modules.  Finally, the Python Reference Manual describes the syntax and semantics of the core language
       in (perhaps too) much detail.  (These documents may be located via the INTERNET RESOURCES below; they may be installed on  your	system	as
       well.)

       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.

       Documentation for installed Python modules and packages can be viewed by running the pydoc program.

COMMAND LINE OPTIONS

       -c command
	      Specify the command to execute (see next section).  This terminates the option list (following options are passed  as  arguments	to
	      the command).

       -d     Turn on parser debugging output (for wizards only, depending on compilation options).

       -E     Ignore environment variables like PYTHONPATH and PYTHONHOME that modify the behavior of the interpreter.

       -h     Prints the usage for the interpreter executable and exits.

       -i     When  a  script  is passed as first argument or the -c option is used, enter interactive mode after executing the script or the com-
	      mand.  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.

       -m module-name
	      Searches sys.path for the named module and runs the corresponding .py file as a script.

       -O     Turn  on	basic  optimizations.	This changes the filename extension for compiled (bytecode) files from .pyc to .pyo.  Given twice,
	      causes docstrings to be discarded.

       -Q argument
	      Division control; see PEP 238.  The argument must be one of "old" (the default, int/int and long/long return an int or long),  "new"
	      (new  division semantics, i.e. int/int and long/long returns a float), "warn" (old division semantics with a warning for int/int and
	      long/long), or "warnall" (old division semantics with a warning for all use of the division operator).  For a use of "warnall",  see
	      the Tools/scripts/fixdiv.py script.

       -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.	On systems where it matters, also put stdin, stdout and stderr	in  binary
	      mode.   Note that there is internal buffering in xreadlines(), readlines() and file-object iterators ("for line in sys.stdin") which
	      is not influenced by this option.  To work around this, you will want to use "sys.stdin.readline()" inside a "while 1:" loop.

       -v     Print a message each time a module is initialized, showing the place (filename or built-in module) from which it	is  loaded.   When
	      given  twice,  print  a  message for each file that is checked for when searching for a module.  Also provides information on module
	      cleanup at exit.

       -V     Prints the Python version number of the executable and exits.

       -W argument
	      Warning control.	Python sometimes prints warning message to  sys.stderr.   A  typical  warning  message	has  the  following  form:
	      file:line:  category: message.  By default, each warning is printed once for each source line where it occurs.  This option controls
	      how often warnings are printed.  Multiple -W options may be given; when a warning matches more than one option, the action  for  the
	      last  matching  option  is  performed.   Invalid -W options are ignored (a warning message is printed about invalid options when the
	      first warning is issued).  Warnings can also be controlled from within a Python program using the warnings module.

	      The simplest form of argument is one of the following action strings (or a unique abbreviation):	ignore	to  ignore  all  warnings;
	      default to explicitly request the default behavior (printing each warning once per source line); all to print a warning each time it
	      occurs (this may generate many messages if a warning is triggered repeatedly for the same source line, such as inside a loop);  mod-
	      ule  to  print  each  warning  only  only the first time it occurs in each module; once to print each warning only the first time it
	      occurs in the program; or error to raise an exception instead of printing a warning message.

	      The full form of argument is action:message:category:module:line.  Here, action is as explained above but only applies  to  messages
	      that  match  the	remaining fields.  Empty fields match all values; trailing empty fields may be omitted.  The message field matches
	      the start of the warning message printed; this match is case-insensitive.  The category field matches the  warning  category.   This
	      must be a class name; the match test whether the actual warning category of the message is a subclass of the specified warning cate-
	      gory.  The full class name must be given.  The module field matches the (fully-qualified) module name; this match is case-sensitive.
	      The line field matches the line number, where zero matches all line numbers and is thus equivalent to an omitted line number.

       -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!

INTERPRETER INTERFACE

       The interpreter interface resembles that of the UNIX shell: when called with standard input connected to a tty device, it prompts for  com-
       mands 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  mul-
       tiple statements separated by newlines.	Leading whitespace is significant in Python statements!  In non-interactive mode, the entire input
       is parsed before 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[0] is an empty string; 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 KeyboardInterrupt 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; ${prefix} and ${exec_prefix}  are  installation-dependent  and
       should be interpreted as for GNU software; they may be the same.  The default for both is /usr/local.

       ${exec_prefix}/bin/python
	      Recommended location of the interpreter.

       ${prefix}/lib/python<version>
       ${exec_prefix}/lib/python<version>
	      Recommended locations of the directories containing the standard modules.

       ${prefix}/include/python<version>
       ${exec_prefix}/include/python<version>
	      Recommended  locations  of  the  directories  containing the include files needed for developing Python extensions and embedding the
	      interpreter.

       ~/.pythonrc.py
	      User-specific initialization file loaded by the user module; not used by default or by most applications.

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  dif-
	      ferent 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-existent directories are silently ignored.  The default search path is installation dependent, but  gener-
	      ally  begins  with ${prefix}/lib/python<version> (see PYTHONHOME above).	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 inter-
	      active 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.

       PYTHONY2K
	      Set this to a non-empty string to cause the time module to require dates specified as strings to include	4-digit  years,  otherwise
	      2-digit years are converted based on rules described in the time module documentation.

       PYTHONOPTIMIZE
	      If  this is set to a non-empty string it is equivalent to specifying the -O option. If set to an integer, it is equivalent to speci-
	      fying -O multiple times.

       PYTHONDEBUG
	      If this is set to a non-empty string it is equivalent to specifying the -d option. If set to an integer, it is equivalent to  speci-
	      fying -d multiple times.

       PYTHONINSPECT
	      If this is set to a non-empty string it is equivalent to specifying the -i option.

       PYTHONUNBUFFERED
	      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. If set to an integer, it is equivalent to speci-
	      fying -v multiple times.

INTERACTIVE INPUT EDITING AND HISTORY SUBSTITUTION

       The Python inteterpreter supports editing of the current input line and history substitution, similar to facilities found in the Korn shell
       and  the GNU Bash shell.  However, rather than being implemented using the GNU Readline library, this Python interpreter uses the BSD Edit-
       Line library editline(3) with a GNU Readline emulation layer.

       The readline module provides the access to the EditLine library, but there are a few major differences compared to a traditional  implemen-
       tation  using  the  Readline library.  The command language used in the preference files is that of EditLine, as described in editrc(5) and
       not that used by the Readline library.  This also means that the parse_and_bind() routines uses EditLine commands.  And the preference file
       itself is ~/.editrc instead of ~/.inputrc.

       For  example,  the  rlcompleter	module,  which	defines  a completion function for the readline modules, works correctly with the EditLine
       libraries, but needs to be initialized somewhat differently:

	      import rlcompleter
	      import readline
	      readline.parse_and_bind("bind ^I rl_complete")

       For vi mode, one needs:

	      readline.parse_and_bind("bind -v")

AUTHOR

       The Python Software Foundation: http://www.python.org/psf

INTERNET RESOURCES

       Main website:  http://www.python.org/
       Documentation:  http://docs.python.org/
       Community website:  http://starship.python.net/
       Developer resources:  http://www.python.org/dev/
       FTP:  ftp://ftp.python.org/pub/python/
       Module repository:  http://www.vex.net/parnassus/
       Newsgroups:  comp.lang.python, comp.lang.python.announce

LICENSING

       Python is distributed under an Open Source license.  See the file "LICENSE" in the Python source distribution for information  on  terms  &
       conditions for accessing and otherwise using Python and for a DISCLAIMER OF ALL WARRANTIES.

					       $Date: 2005-03-20 15:16:03 +0100 (Sun, 20 Mar 2005) $					 PYTHON(1)