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PYTHON(1)										PYTHON(1)

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

       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 ]

       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.
       (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

       -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

       -E     Ignore environment variables like PYTHONPATH and PYTHONHOME that modify the  behav-
	      ior 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 interac-
	      tive mode after executing the script or the command.  It does not read the $PYTHON-
	      STARTUP 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

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

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

       -R     Turn  on "hash randomization", so that the hash() values of str, bytes and datetime
	      objects are "salted" with an  unpredictable  pseudo-random  value.   Although  they
	      remain  constant	within	an  individual	Python	process, they are not predictable
	      between repeated 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 insertion,
	      O(n^2)  complexity.   See  http://www.ocert.org/advisories/ocert-2011-003.html  for

       -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 warn-
	      ing 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     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 mat-
	      ters, also put stdin, stdout and stderr in binary mode.  Note that there is  inter-
	      nal  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 informa-
	      tion 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
	      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 warn-
	      ing 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-insensi-
	      tive.  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.

       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 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 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.

	      Recommended location of the interpreter.

	      Recommended locations of the directories containing the standard modules.

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

	      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<version>  and  ${exec_prefix}/lib/python<ver-
	      sion>,  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}.

	      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  depen-
	      dent,  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 pro-
	      gram as the variable sys.path .

	      If  this	is the name of a readable file, the Python commands in that file are exe-
	      cuted before the first prompt is displayed in interactive mode.  The file  is  exe-
	      cuted  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 interac-
	      tive 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 specifying 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 specifying 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 specifying the -B option
	      (don't try to write .py[co] files).

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

	      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'.

	      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).

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

	      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.

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

	      If  this	variable  is set to "random", the effect is the same as specifying the -R
	      option: a random value is used to seed  the  hashes  of  str,  bytes  and  datetime

	      If PYTHONHASHSEED is set to an integer value, it is used as a fixed seed for gener-
	      ating the hash() of the types covered by the hash randomization.	Its purpose is to
	      allow  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.

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

       Main website:  http://www.python.org/
       Documentation:  http://docs.python.org/
       Developer resources:  http://www.python.org/dev/
       Downloads:  http://python.org/download/
       Module repository:  http://pypi.python.org/
       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 DISCLAIMER OF ALL WARRANTIES.

					      $Date$					PYTHON(1)
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