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PYTHON(1)                              General Commands Manual                             PYTHON(1)



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

SYNOPSIS
       python [ -B ] [ -d ] [ -E ] [ -h ] [ -i ] [ -m module-name ]
              [ -O ] [ -OO ] [ -R ] [ -Q argument ] [ -s ] [ -S ] [ -t ] [ -u ]
              [ -v ] [ -V ] [ -W argument ] [ -x ] [ -3 ] [ -?  ]
              [ -c command | script | - ] [ arguments ]

DESCRIPTION
       Python is an interpreted, interactive, object-oriented programming language that combines re‐
       markable power with very clear syntax.  For an introduction to programming in Python, see the
       Python  Tutorial.   The  Python Library Reference documents built-in and standard types, con‐
       stants, 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 sys‐
       tems  such  modules may be dynamically loaded.  Python is also adaptable as an extension lan‐
       guage 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
       -B     Don't write .py[co] files on import. See also PYTHONDONTWRITEBYTECODE.

       -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 ,  -? ,  --help
              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  corresponding  .py  file  as  a
              script.

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

       -OO    Discard docstrings in addition to the -O optimizations.

       -R     Turn on "hash randomization", so that the hash() values of str, bytes and datetime ob‐
              jects  are  "salted"  with an unpredictable pseudo-random value.  Although they remain
              constant within an individual Python process, they are  not  predictable  between  re‐
              peated invocations of Python.

              This  is  intended  to  provide protection against a denial of service caused by care‐
              fully-chosen inputs that exploit the worst case performance of  a  dict  construction,
              O(n^2)  complexity.   See  http://www.ocert.org/advisories/ocert-2011-003.html for de‐
              tails.

       -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/fix‐
              div.py script.

       -s     Don't add user site directory to sys.path.

       -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 buffer‐
              ing 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 ,  --version
              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 con‐
              trols how often warnings are printed.  Multiple -W options may be given; when a  warn‐
              ing  matches  more  than  one  option, the action for the last matching option is per‐
              formed.  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  ab‐
              breviation):  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); module to print  each  warning  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  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  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!

       -3     Warn about Python 3.x incompatibilities that 2to3 cannot trivially fix.

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.  Lead‐
       ing whitespace is significant in Python statements!  In non-interactive mode, the entire  in‐
       put 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  in‐
       terpreter 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 excep‐
       tion occurs, a stack trace is printed and control returns to the primary prompt;  in  non-in‐
       teractive  mode,  the interpreter exits after printing the stack trace.  The interrupt signal
       raises the KeyboardInterrupt exception; other UNIX signals are not caught (except  that  SIG‐
       PIPE 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.  On Debian GNU/{Hurd,Linux} the default for both is /usr.

       ${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  de‐
              veloping 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  de‐
              faulting  to /usr/local.  When $PYTHONHOME is set to a single directory, its value re‐
              places 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-existent  di‐
              rectories  are  silently  ignored.  The default search path is installation dependent,
              but generally 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 interactive mode.  The file is executed in the
              same name space where interactive commands are executed so that objects defined or im‐
              ported  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 specifying -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 specifying -d multiple times.

       PYTHONDONTWRITEBYTECODE
              If this is set to a non-empty string it is equivalent  to  specifying  the  -B  option
              (don't try to write .py[co] files).

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

       PYTHONIOENCODING
              If  this  is  set  before  running the interpreter, it overrides the encoding used for
              stdin/stdout/stderr, in the syntax encodingname:errorhandler The errorhandler part  is
              optional and has the same meaning as in str.encode. For stderr, the errorhandler
               part is ignored; the handler will always be ´backslashreplace´.

       PYTHONNOUSERSITE
              If  this  is  set  to  a non-empty string it is equivalent to specifying the -s option
              (Don't add the user site directory to sys.path).

       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 specifying -v multiple times.

       PYTHONWARNINGS
              If  this  is set to a comma-separated string it is equivalent to specifying the -W op‐
              tion for each separate value.

       PYTHONHASHSEED
              If this variable is set to "random", the effect is the same as specifying the  -R  op‐
              tion: a random value is used to seed the hashes of str, bytes and datetime objects.

              If  PYTHONHASHSEED is set to an integer value, it is used as a fixed seed for generat‐
              ing the hash() of the types covered by the hash randomization.  Its purpose is to  al‐
              low  repeatable hashing, such as for selftests for the interpreter itself, or to allow
              a cluster of python processes to share hash values.

              The integer must be a decimal number in  the  range  [0,4294967295].   Specifying  the
              value 0 will lead to the same hash values as when hash randomization is disabled.

AUTHOR
       The Python Software Foundation: https://www.python.org/psf/

INTERNET RESOURCES
       Main website:  https://www.python.org/
       Documentation:    file:///usr/share/doc/python2.7/html/index.html   (python-doc  package)  or
       https://docs.python.org/2/
       Developer resources:  https://docs.python.org/devguide/
       Downloads:  https://www.python.org/downloads/
       Module repository:  https://pypi.python.org/
       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.



                                                                                           PYTHON(1)
python2.7(1)
NAME SYNOPSIS DESCRIPTION COMMAND LINE OPTIONS
-B Don't write .py[co] files on import. See also PYTHONDONTWRITEBYTECODE. -c 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 -h , -? , --help -i When a script is passed as first argument or the -c option is used, enter interactive -m module-name -O Turn on basic optimizations. This changes the filename extension for compiled (byte‐ -OO Discard docstrings in addition to the -O optimizations. -R Turn on "hash randomization", so that the hash() values of str, bytes and datetime ob‐ -Q argument -s Don't add user site directory to sys.path. -S Disable the import of the module site and the site-dependent manipulations of sys.path -t Issue a warning when a source file mixes tabs and spaces for indentation in a way that -u Force stdin, stdout and stderr to be totally unbuffered. On systems where it matters, -v Print a message each time a module is initialized, showing the place (filename or -V , --version -W argument -x Skip the first line of the source. This is intended for a DOS specific hack only. -3 Warn about Python 3.x incompatibilities that 2to3 cannot trivially fix.
INTERPRETER INTERFACE FILES AND DIRECTORIES ENVIRONMENT VARIABLES AUTHOR INTERNET RESOURCES LICENSING

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