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PYTHON(1)                                                            PYTHON(1)


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


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


       Python is an interpreted, interactive, object-oriented programming lan-
       guage  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 (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 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.


       -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 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 correspond-
              ing .py file as a script.

       -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/ 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

       -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  xread-
              lines(),  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 mod-

              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 it occurs (this may generate many messages if 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  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: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 error messages
              will be off by one!


       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  multi-
       ple  statements  separated by newlines.  Leading whitespace is signifi-
       cant 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.


       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.

              Recommended location of the interpreter.

              Recommended locations of the directories containing the standard

              Recommended  locations of the directories containing the include
              files needed for developing Python extensions and embedding  the

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


              Change the  location  of  the  standard  Python  libraries.   By
              default, the libraries are searched in ${prefix}/lib/python<ver-
              sion> 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 ${pre-

              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-existent  directories  are
              silently ignored.   The  default  search  path  is  installation
              dependent,  but  generally begins with ${prefix}/lib/python<ver-
              sion> (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 .

              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.

              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.

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

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

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

              If this is set to a non-empty string it is equivalent to  speci-
              fying the -u option.

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


       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  EditLine
       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 implementa-
       tion  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 func-
       tion 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")


       The Python Software Foundation:


       Main website:
       Community website:
       Developer resources:
       Module repository:
       Newsgroups:  comp.lang.python, comp.lang.python.announce


       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 DIS-

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

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