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PYTHON(1)                                                            PYTHON(1)



NAME
       python  - an interpreted, interactive, object-oriented programming lan-
       guage

SYNOPSIS
       python [ -d ] [ -E ] [ -h ] [ -i ] [ -O ]
              [ -Q argument ] [ -S ] [ -t ] [ -u ]
              [ -v ] [ -V ] [ -W argument ] [ -x ]
              [ -c command | script | - ] [ arguments ]

DESCRIPTION
       Python is an interpreted, interactive, object-oriented programming lan-
       guage  that  combines  remarkable power with very clear(1,3x,3x clrtobot) syntax.  For an
       introduction to programming in(1,8) 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(1,8) (per-
       haps too) much detail.  (These documents may be located via the  INTER-
       NET RESOURCES below; they may be installed on your system as well.)

       Python's basic power can be extended with your own modules written in(1,8) C
       or C++.  On most  systems  such  modules  may  be  dynamically  loaded.
       Python is also adaptable as an extension language for existing applica-
       tions.  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 termi-
              nates 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
              command.  It does not read(2,n,1 builtins) the $PYTHONSTARTUP file.  This can be
              useful to inspect global variables  or  a  stack  trace(3x,n,3x _nc_tracebits)  when  a
              script raises an exception.

       -O     Turn  on  basic optimizations.  This changes the filename exten-
              sion 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(1,n) mixes  tabs  and  spaces  for
              indentation  in(1,8) a way that makes it depend on the worth of a tab
              expressed in(1,8) spaces.  Issue an error(8,n) 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(1,8)
              binary  mode.   Note  that there is internal buffering in(1,8) xread-
              lines(), readlines() and file-object  iterators  ("for  line  in(1,8)
              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(1,2,n) 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(1,n) that is checked
              for when searching for a module.  Also provides  information  on
              module cleanup at exit.

       -V     Prints the Python version(1,3,5) 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(1,n):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  mod-
              ule.

              The  simplest  form  of  argument is one of the following action
              strings (or a unique abbreviation): ignore to ignore  all  warn-
              ings; default to explicitly request the default behavior (print-
              ing each warning once per source line); all to print  a  warning
              each  time(1,2,n) it occurs (this may generate many messages if(3,n) a warn-
              ing is triggered repeatedly for the same source  line,  such  as
              inside a loop); module to print each warning only only the first
              time(1,2,n) it occurs in(1,8) each module; once to print each  warning  only
              the  first  time(1,2,n)  it occurs in(1,8) the program; or error(8,n) to raise(3,n) an
              exception instead of printing a warning message.

              The  full  form  of  argument  is   action:message:category:mod-
              ule: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 warn-
              ing 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 category.  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  num-
              ber,  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(1,8) error(8,n) 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(1,4) device, it prompts for commands
       and executes them until an EOF is read(2,n,1 builtins); when called with  a  file(1,n)  name
       argument  or  with  a  file(1,n)  as standard input, it reads and executes a
       script from that file(1,n); when called with -c  command,  it  executes  the
       Python  statement(s) given as command.  Here command may contain multi-
       ple statements separated by newlines.  Leading whitespace  is  signifi-
       cant  in(1,8)  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(1,8) the Python variable sys.argv , which is a list
       of strings (you must first import sys to be able to access(2,5) it).  If  no
       script  name  is  given, sys.argv[0] is an empty string(3,n); if(3,n) -c is used,
       sys.argv[0] contains the string(3,n) '-c'.  Note that options interpreted by
       the Python interpreter itself are not placed in(1,8) 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(3x,n,3x _nc_tracebits)  is printed and control returns to the primary
       prompt; in(1,8) non-interactive mode, the interpreter exits  after  printing
       the  stack  trace.   The  interrupt signal(2,7) raises the KeyboardInterrupt
       exception; other UNIX signals are not caught (except  that  SIGPIPE  is
       sometimes  ignored, in(1,8) favor of the IOError exception).  Error messages
       are written to stderr.

FILES AND DIRECTORIES
       These are subject to difference depending on local installation conven-
       tions;  ${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(1,3,5)>
       ${exec_prefix}/lib/python<version(1,3,5)>
              Recommended locations of the directories containing the standard
              modules.

       ${prefix}/include/python<version(1,3,5)>
       ${exec_prefix}/include/python<version(1,3,5)>
              Recommended locations of the directories containing the  include
              files  needed for developing Python extensions and embedding the
              interpreter.

       ~/.pythonrc.py
              User-specific initialization file(1,n) 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(1,8) ${prefix}/lib/python<ver-
              sion(1,3,5)>  and  ${exec_prefix}/lib/python<version(1,3,5)>,  where ${prefix}
              and ${exec_prefix} are installation-dependent directories,  both
              defaulting  to  /usr/local.  When $PYTHONHOME is set(7,n,1 builtins) to a single
              directory, its value replaces both ${prefix} and ${exec_prefix}.
              To specify different values for these, set(7,n,1 builtins) $PYTHONHOME to ${pre-
              fix}:${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 path-
              names  separated  by  colons.   Non-existant   directories   are
              silently  ignored.   The  default  search  path  is installation
              dependent, but generally begins  with  ${prefix}/lib/python<ver-
              sion(1,3,5)> (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(1,8) the path in(1,8) 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(1,n), the Python commands in(1,8)
              that file(1,n) are executed before the first prompt is  displayed  in(1,8)
              interactive  mode.   The file(1,n) is executed in(1,8) the same name space
              where interactive commands are executed so that objects  defined
              or  imported  in(1,8)  it  can  be  used without qualification in(1,8) the
              interactive session.  You can also change  the  prompts  sys.ps1
              and sys.ps2 in(1,8) this file.

       PYTHONY2K
              Set  this  to  a  non-empty  string(3,n)  to cause the time(1,2,n) module to
              require dates specified as strings  to  include  4-digit  years,
              otherwise  2-digit  years are converted based on rules described
              in(1,8) the time(1,2,n) module documentation.

       PYTHONOPTIMIZE
              If this is set(7,n,1 builtins) to a non-empty string(3,n) it is equivalent to  speci-
              fying  the  -O option. If set(7,n,1 builtins) to an integer, it is equivalent to
              specifying -O multiple times.

       PYTHONDEBUG
              If this is set(7,n,1 builtins) to a non-empty string(3,n) it is equivalent to  speci-
              fying  the  -d option. If set(7,n,1 builtins) to an integer, it is equivalent to
              specifying -d multiple times.

       PYTHONINSPECT
              If this is set(7,n,1 builtins) to a non-empty string(3,n) it is equivalent to  speci-
              fying the -i option.

       PYTHONUNBUFFERED
              If  this is set(7,n,1 builtins) to a non-empty string(3,n) it is equivalent to speci-
              fying the -u option.

       PYTHONVERBOSE
              If this is set(7,n,1 builtins) to a non-empty string(3,n) it is equivalent to  speci-
              fying  the  -v option. If set(7,n,1 builtins) to an integer, it is equivalent to
              specifying -v multiple times.

AUTHOR
       Guido van Rossum

       E-mail: guido@python.org

       And a cast of thousands.

INTERNET RESOURCES
       Main website:  http://www.python.org/
       Documentation:  http://www.python.org/doc/
       Community website:  http://starship.python.net/
       Developer resources:  http://sourceforge.net/project/python/
       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(1,n)
       "LICENSE"  in(1,8) the Python source distribution for information on terms &
       conditions for accessing and otherwise using  Python  and  for  a  DIS-
       CLAIMER OF ALL WARRANTIES.



                         $Date: 2003/05/26 05:15:35 $                PYTHON(1)

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