Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 1 | .. highlightlang:: none |
| 2 | |
Georg Brandl | 87983f2 | 2007-12-01 23:12:45 +0000 | [diff] [blame] | 3 | .. _using-on-general: |
| 4 | |
Georg Brandl | 1cddfed | 2007-10-20 18:33:20 +0000 | [diff] [blame] | 5 | Command line and environment |
| 6 | ============================ |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 7 | |
| 8 | The CPython interpreter scans the command line and the environment for various |
| 9 | settings. |
| 10 | |
| 11 | .. note:: |
| 12 | |
Georg Brandl | cbcfe4f | 2007-12-03 19:57:02 +0000 | [diff] [blame] | 13 | Other implementations' command line schemes may differ. See |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 14 | :ref:`implementations` for further resources. |
| 15 | |
| 16 | |
Georg Brandl | 87983f2 | 2007-12-01 23:12:45 +0000 | [diff] [blame] | 17 | .. _using-on-cmdline: |
| 18 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 19 | Command line |
| 20 | ------------ |
| 21 | |
| 22 | When invoking Python, you may specify any of these options:: |
| 23 | |
Christian Heimes | af748c3 | 2008-05-06 22:41:46 +0000 | [diff] [blame] | 24 | python [-dEiOQsStuUvxX3?] [-c command | -m module-name | script | - ] [args] |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 25 | |
| 26 | The most common use case is, of course, a simple invocation of a script:: |
| 27 | |
| 28 | python myscript.py |
| 29 | |
| 30 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 31 | .. _using-on-interface-options: |
| 32 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 33 | Interface options |
| 34 | ~~~~~~~~~~~~~~~~~ |
| 35 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 36 | The interpreter interface resembles that of the UNIX shell, but provides some |
| 37 | additional methods of invocation: |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 38 | |
| 39 | * When called with standard input connected to a tty device, it prompts for |
| 40 | commands and executes them until an EOF (an end-of-file character, you can |
| 41 | produce that with *Ctrl-D* on UNIX or *Ctrl-Z, Enter* on Windows) is read. |
| 42 | * When called with a file name argument or with a file as standard input, it |
| 43 | reads and executes a script from that file. |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 44 | * When called with a directory name argument, it reads and executes an |
| 45 | appropriately named script from that directory. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 46 | * When called with ``-c command``, it executes the Python statement(s) given as |
| 47 | *command*. Here *command* may contain multiple statements separated by |
| 48 | newlines. Leading whitespace is significant in Python statements! |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 49 | * When called with ``-m module-name``, the given module is located on the |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 50 | Python module path and executed as a script. |
| 51 | |
| 52 | In non-interactive mode, the entire input is parsed before it is executed. |
| 53 | |
| 54 | An interface option terminates the list of options consumed by the interpreter, |
| 55 | all consecutive arguments will end up in :data:`sys.argv` -- note that the first |
| 56 | element, subscript zero (``sys.argv[0]``), is a string reflecting the program's |
| 57 | source. |
| 58 | |
| 59 | .. cmdoption:: -c <command> |
| 60 | |
| 61 | Execute the Python code in *command*. *command* can be one ore more |
| 62 | statements separated by newlines, with significant leading whitespace as in |
| 63 | normal module code. |
| 64 | |
| 65 | If this option is given, the first element of :data:`sys.argv` will be |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 66 | ``"-c"`` and the current directory will be added to the start of |
| 67 | :data:`sys.path` (allowing modules in that directory to be imported as top |
| 68 | level modules). |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 69 | |
| 70 | |
| 71 | .. cmdoption:: -m <module-name> |
| 72 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 73 | Search :data:`sys.path` for the named module and execute its contents as |
| 74 | the :mod:`__main__` module. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 75 | |
| 76 | Since the argument is a *module* name, you must not give a file extension |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 77 | (``.py``). The ``module-name`` should be a valid Python module name, but |
| 78 | the implementation may not always enforce this (e.g. it may allow you to |
| 79 | use a name that includes a hyphen). |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 80 | |
| 81 | .. note:: |
| 82 | |
| 83 | This option cannot be used with builtin modules and extension modules |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 84 | written in C, since they do not have Python module files. However, it |
| 85 | can still be used for precompiled modules, even if the original source |
| 86 | file is not available. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 87 | |
| 88 | If this option is given, the first element of :data:`sys.argv` will be the |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 89 | full path to the module file. As with the :option:`-c` option, the current |
| 90 | directory will be added to the start of :data:`sys.path`. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 91 | |
| 92 | Many standard library modules contain code that is invoked on their execution |
| 93 | as a script. An example is the :mod:`timeit` module:: |
| 94 | |
| 95 | python -mtimeit -s 'setup here' 'benchmarked code here' |
| 96 | python -mtimeit -h # for details |
| 97 | |
| 98 | .. seealso:: |
| 99 | :func:`runpy.run_module` |
| 100 | The actual implementation of this feature. |
| 101 | |
| 102 | :pep:`338` -- Executing modules as scripts |
| 103 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 104 | .. versionadded:: 2.4 |
| 105 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 106 | .. versionchanged:: 2.5 |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 107 | The named module can now be located inside a package. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 108 | |
| 109 | |
| 110 | .. describe:: - |
| 111 | |
| 112 | Read commands from standard input (:data:`sys.stdin`). If standard input is |
| 113 | a terminal, :option:`-i` is implied. |
| 114 | |
| 115 | If this option is given, the first element of :data:`sys.argv` will be |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 116 | ``"-"`` and the current directory will be added to the start of |
| 117 | :data:`sys.path`. |
| 118 | |
| 119 | |
| 120 | .. describe:: <script> |
| 121 | |
| 122 | Execute the Python code contained in *script*, which must be a filesystem |
| 123 | path (absolute or relative) referring to either a Python file, a directory |
| 124 | containing a ``__main__.py`` file, or a zipfile containing a |
| 125 | ``__main__.py`` file. |
| 126 | |
| 127 | If this option is given, the first element of :data:`sys.argv` will be the |
| 128 | script name as given on the command line. |
| 129 | |
| 130 | If the script name refers directly to a Python file, the directory |
| 131 | containing that file is added to the start of :data:`sys.path`, and the |
| 132 | file is executed as the :mod:`__main__` module. |
| 133 | |
| 134 | If the script name refers to a directory or zipfile, the script name is |
| 135 | added to the start of :data:`sys.path` and the ``__main__.py`` file in |
| 136 | that location is executed as the :mod:`__main__` module. |
| 137 | |
| 138 | .. versionchanged:: 2.5 |
| 139 | Directories and zipfiles containing a ``__main__.py`` file at the top |
| 140 | level are now considered valid Python scripts. |
| 141 | |
| 142 | If no interface option is given, :option:`-i` is implied, ``sys.argv[0]`` is |
| 143 | an empty string (``""``) and the current directory will be added to the |
| 144 | start of :data:`sys.path`. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 145 | |
Georg Brandl | 14da8e8 | 2008-11-07 08:27:39 +0000 | [diff] [blame] | 146 | .. seealso:: :ref:`tut-invoking` |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 147 | |
| 148 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 149 | Generic options |
| 150 | ~~~~~~~~~~~~~~~ |
| 151 | |
| 152 | .. cmdoption:: -? |
| 153 | -h |
| 154 | --help |
| 155 | |
| 156 | Print a short description of all command line options. |
| 157 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 158 | .. versionchanged:: 2.5 |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 159 | The ``--help`` variant. |
| 160 | |
| 161 | |
| 162 | .. cmdoption:: -V |
| 163 | --version |
| 164 | |
| 165 | Print the Python version number and exit. Example output could be:: |
| 166 | |
| 167 | Python 2.5.1 |
| 168 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 169 | .. versionchanged:: 2.5 |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 170 | The ``--version`` variant. |
| 171 | |
| 172 | |
| 173 | Miscellaneous options |
| 174 | ~~~~~~~~~~~~~~~~~~~~~ |
| 175 | |
Georg Brandl | 2da0fce | 2008-01-07 17:09:35 +0000 | [diff] [blame] | 176 | .. cmdoption:: -B |
| 177 | |
| 178 | If given, Python won't try to write ``.pyc`` or ``.pyo`` files on the |
| 179 | import of source modules. See also :envvar:`PYTHONDONTWRITEBYTECODE`. |
| 180 | |
| 181 | .. versionadded:: 2.6 |
| 182 | |
| 183 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 184 | .. cmdoption:: -d |
| 185 | |
| 186 | Turn on parser debugging output (for wizards only, depending on compilation |
| 187 | options). See also :envvar:`PYTHONDEBUG`. |
| 188 | |
| 189 | |
| 190 | .. cmdoption:: -E |
| 191 | |
Georg Brandl | c5004f3 | 2007-10-20 19:05:45 +0000 | [diff] [blame] | 192 | Ignore all :envvar:`PYTHON*` environment variables, e.g. |
Georg Brandl | 3507333 | 2007-10-20 19:08:36 +0000 | [diff] [blame] | 193 | :envvar:`PYTHONPATH` and :envvar:`PYTHONHOME`, that might be set. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 194 | |
Georg Brandl | c5004f3 | 2007-10-20 19:05:45 +0000 | [diff] [blame] | 195 | .. versionadded:: 2.2 |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 196 | |
| 197 | |
| 198 | .. cmdoption:: -i |
| 199 | |
| 200 | When a script is passed as first argument or the :option:`-c` option is used, |
| 201 | enter interactive mode after executing the script or the command, even when |
| 202 | :data:`sys.stdin` does not appear to be a terminal. The |
| 203 | :envvar:`PYTHONSTARTUP` file is not read. |
| 204 | |
| 205 | This can be useful to inspect global variables or a stack trace when a script |
| 206 | raises an exception. See also :envvar:`PYTHONINSPECT`. |
| 207 | |
| 208 | |
| 209 | .. cmdoption:: -O |
| 210 | |
| 211 | Turn on basic optimizations. This changes the filename extension for |
Georg Brandl | 5e52db0 | 2007-10-21 10:45:46 +0000 | [diff] [blame] | 212 | compiled (:term:`bytecode`) files from ``.pyc`` to ``.pyo``. See also |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 213 | :envvar:`PYTHONOPTIMIZE`. |
| 214 | |
| 215 | |
| 216 | .. cmdoption:: -OO |
| 217 | |
| 218 | Discard docstrings in addition to the :option:`-O` optimizations. |
| 219 | |
| 220 | |
| 221 | .. cmdoption:: -Q <arg> |
| 222 | |
| 223 | Division control. The argument must be one of the following: |
| 224 | |
| 225 | ``old`` |
| 226 | division of int/int and long/long return an int or long (*default*) |
| 227 | ``new`` |
| 228 | new division semantics, i.e. division of int/int and long/long returns a |
| 229 | float |
| 230 | ``warn`` |
| 231 | old division semantics with a warning for int/int and long/long |
| 232 | ``warnall`` |
| 233 | old division semantics with a warning for all uses of the division operator |
| 234 | |
| 235 | .. seealso:: |
| 236 | :file:`Tools/scripts/fixdiv.py` |
| 237 | for a use of ``warnall`` |
| 238 | |
| 239 | :pep:`238` -- Changing the division operator |
| 240 | |
| 241 | |
Christian Heimes | af748c3 | 2008-05-06 22:41:46 +0000 | [diff] [blame] | 242 | .. cmdoption:: -s |
| 243 | |
| 244 | Don't add user site directory to sys.path |
| 245 | |
| 246 | .. versionadded:: 2.6 |
| 247 | |
| 248 | .. seealso:: |
| 249 | |
| 250 | :pep:`370` -- Per user site-packages directory |
| 251 | |
| 252 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 253 | .. cmdoption:: -S |
| 254 | |
| 255 | Disable the import of the module :mod:`site` and the site-dependent |
| 256 | manipulations of :data:`sys.path` that it entails. |
| 257 | |
| 258 | |
| 259 | .. cmdoption:: -t |
| 260 | |
| 261 | Issue a warning when a source file mixes tabs and spaces for indentation in a |
| 262 | way that makes it depend on the worth of a tab expressed in spaces. Issue an |
| 263 | error when the option is given twice (:option:`-tt`). |
| 264 | |
| 265 | |
| 266 | .. cmdoption:: -u |
| 267 | |
| 268 | Force stdin, stdout and stderr to be totally unbuffered. On systems where it |
| 269 | matters, also put stdin, stdout and stderr in binary mode. |
| 270 | |
Georg Brandl | f4ef23f | 2007-10-30 17:51:18 +0000 | [diff] [blame] | 271 | Note that there is internal buffering in :meth:`file.readlines` and |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 272 | :ref:`bltin-file-objects` (``for line in sys.stdin``) which is not influenced |
| 273 | by this option. To work around this, you will want to use |
Georg Brandl | f4ef23f | 2007-10-30 17:51:18 +0000 | [diff] [blame] | 274 | :meth:`file.readline` inside a ``while 1:`` loop. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 275 | |
| 276 | See also :envvar:`PYTHONUNBUFFERED`. |
| 277 | |
| 278 | |
| 279 | .. XXX should the -U option be documented? |
| 280 | |
| 281 | .. cmdoption:: -v |
| 282 | |
| 283 | Print a message each time a module is initialized, showing the place |
| 284 | (filename or built-in module) from which it is loaded. When given twice |
| 285 | (:option:`-vv`), print a message for each file that is checked for when |
| 286 | searching for a module. Also provides information on module cleanup at exit. |
| 287 | See also :envvar:`PYTHONVERBOSE`. |
| 288 | |
| 289 | |
| 290 | .. cmdoption:: -W arg |
| 291 | |
| 292 | Warning control. Python's warning machinery by default prints warning |
| 293 | messages to :data:`sys.stderr`. A typical warning message has the following |
| 294 | form:: |
| 295 | |
| 296 | file:line: category: message |
| 297 | |
| 298 | By default, each warning is printed once for each source line where it |
| 299 | occurs. This option controls how often warnings are printed. |
| 300 | |
| 301 | Multiple :option:`-W` options may be given; when a warning matches more than |
| 302 | one option, the action for the last matching option is performed. Invalid |
| 303 | :option:`-W` options are ignored (though, a warning message is printed about |
| 304 | invalid options when the first warning is issued). |
| 305 | |
| 306 | Warnings can also be controlled from within a Python program using the |
| 307 | :mod:`warnings` module. |
| 308 | |
| 309 | The simplest form of argument is one of the following action strings (or a |
| 310 | unique abbreviation): |
| 311 | |
| 312 | ``ignore`` |
| 313 | Ignore all warnings. |
| 314 | ``default`` |
| 315 | Explicitly request the default behavior (printing each warning once per |
| 316 | source line). |
| 317 | ``all`` |
| 318 | Print a warning each time it occurs (this may generate many messages if a |
| 319 | warning is triggered repeatedly for the same source line, such as inside a |
| 320 | loop). |
| 321 | ``module`` |
| 322 | Print each warning only only the first time it occurs in each module. |
| 323 | ``once`` |
| 324 | Print each warning only the first time it occurs in the program. |
| 325 | ``error`` |
| 326 | Raise an exception instead of printing a warning message. |
| 327 | |
| 328 | The full form of argument is:: |
| 329 | |
| 330 | action:message:category:module:line |
| 331 | |
| 332 | Here, *action* is as explained above but only applies to messages that match |
| 333 | the remaining fields. Empty fields match all values; trailing empty fields |
| 334 | may be omitted. The *message* field matches the start of the warning message |
| 335 | printed; this match is case-insensitive. The *category* field matches the |
| 336 | warning category. This must be a class name; the match test whether the |
| 337 | actual warning category of the message is a subclass of the specified warning |
| 338 | category. The full class name must be given. The *module* field matches the |
| 339 | (fully-qualified) module name; this match is case-sensitive. The *line* |
| 340 | field matches the line number, where zero matches all line numbers and is |
| 341 | thus equivalent to an omitted line number. |
| 342 | |
| 343 | .. seealso:: |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 344 | :mod:`warnings` -- the warnings module |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 345 | |
| 346 | :pep:`230` -- Warning framework |
| 347 | |
| 348 | |
| 349 | .. cmdoption:: -x |
| 350 | |
| 351 | Skip the first line of the source, allowing use of non-Unix forms of |
| 352 | ``#!cmd``. This is intended for a DOS specific hack only. |
| 353 | |
| 354 | .. warning:: The line numbers in error messages will be off by one! |
| 355 | |
| 356 | |
| 357 | .. cmdoption:: -3 |
| 358 | |
Georg Brandl | 87983f2 | 2007-12-01 23:12:45 +0000 | [diff] [blame] | 359 | Warn about Python 3.x incompatibilities. Among these are: |
| 360 | |
| 361 | * :meth:`dict.has_key` |
| 362 | * :func:`apply` |
| 363 | * :func:`callable` |
| 364 | * :func:`coerce` |
| 365 | * :func:`execfile` |
| 366 | * :func:`reduce` |
| 367 | * :func:`reload` |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 368 | |
Georg Brandl | 4425e7c | 2008-02-23 23:43:01 +0000 | [diff] [blame] | 369 | Using these will emit a :exc:`DeprecationWarning`. |
| 370 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 371 | .. versionadded:: 2.6 |
| 372 | |
| 373 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 374 | |
Georg Brandl | 87983f2 | 2007-12-01 23:12:45 +0000 | [diff] [blame] | 375 | .. _using-on-envvars: |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 376 | |
| 377 | Environment variables |
| 378 | --------------------- |
| 379 | |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 380 | These environment variables influence Python's behavior. |
| 381 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 382 | .. envvar:: PYTHONHOME |
| 383 | |
| 384 | Change the location of the standard Python libraries. By default, the |
Georg Brandl | 21297fa | 2008-01-20 21:10:08 +0000 | [diff] [blame] | 385 | libraries are searched in :file:`{prefix}/lib/python{version}` and |
| 386 | :file:`{exec_prefix}/lib/python{version}`, where :file:`{prefix}` and |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 387 | :file:`{exec_prefix}` are installation-dependent directories, both defaulting |
| 388 | to :file:`/usr/local`. |
| 389 | |
| 390 | When :envvar:`PYTHONHOME` is set to a single directory, its value replaces |
| 391 | both :file:`{prefix}` and :file:`{exec_prefix}`. To specify different values |
Georg Brandl | 21297fa | 2008-01-20 21:10:08 +0000 | [diff] [blame] | 392 | for these, set :envvar:`PYTHONHOME` to :file:`{prefix}:{exec_prefix}`. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 393 | |
| 394 | |
| 395 | .. envvar:: PYTHONPATH |
| 396 | |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 397 | Augment the default search path for module files. The format is the same as |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 398 | the shell's :envvar:`PATH`: one or more directory pathnames separated by |
Georg Brandl | 9c06574 | 2008-03-05 19:31:44 +0000 | [diff] [blame] | 399 | :data:`os.pathsep` (e.g. colons on Unix or semicolons on Windows). |
| 400 | Non-existent directories are silently ignored. |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 401 | |
| 402 | In addition to normal directories, individual :envvar:`PYTHONPATH` entries |
| 403 | may refer to zipfiles containing pure Python modules (in either source or |
| 404 | compiled form). Extension modules cannot be imported from zipfiles. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 405 | |
| 406 | The default search path is installation dependent, but generally begins with |
Georg Brandl | fc29f27 | 2009-01-02 20:25:14 +0000 | [diff] [blame^] | 407 | :file:`{prefix}/lib/python{version}` (see :envvar:`PYTHONHOME` above). It |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 408 | is *always* appended to :envvar:`PYTHONPATH`. |
| 409 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 410 | An additional directory will be inserted in the search path in front of |
| 411 | :envvar:`PYTHONPATH` as described above under |
| 412 | :ref:`using-on-interface-options`. The search path can be manipulated from |
| 413 | within a Python program as the variable :data:`sys.path`. |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 414 | |
| 415 | |
| 416 | .. envvar:: PYTHONSTARTUP |
| 417 | |
| 418 | If this is the name of a readable file, the Python commands in that file are |
| 419 | executed before the first prompt is displayed in interactive mode. The file |
Georg Brandl | a739503 | 2007-10-21 12:15:05 +0000 | [diff] [blame] | 420 | is executed in the same namespace where interactive commands are executed so |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 421 | that objects defined or imported in it can be used without qualification in |
| 422 | the interactive session. You can also change the prompts :data:`sys.ps1` and |
| 423 | :data:`sys.ps2` in this file. |
| 424 | |
| 425 | |
| 426 | .. envvar:: PYTHONY2K |
| 427 | |
| 428 | Set this to a non-empty string to cause the :mod:`time` module to require |
| 429 | dates specified as strings to include 4-digit years, otherwise 2-digit years |
| 430 | are converted based on rules described in the :mod:`time` module |
| 431 | documentation. |
| 432 | |
| 433 | |
| 434 | .. envvar:: PYTHONOPTIMIZE |
| 435 | |
| 436 | If this is set to a non-empty string it is equivalent to specifying the |
| 437 | :option:`-O` option. If set to an integer, it is equivalent to specifying |
| 438 | :option:`-O` multiple times. |
| 439 | |
| 440 | |
| 441 | .. envvar:: PYTHONDEBUG |
| 442 | |
| 443 | If this is set to a non-empty string it is equivalent to specifying the |
| 444 | :option:`-d` option. If set to an integer, it is equivalent to specifying |
| 445 | :option:`-d` multiple times. |
| 446 | |
| 447 | |
| 448 | .. envvar:: PYTHONINSPECT |
| 449 | |
| 450 | If this is set to a non-empty string it is equivalent to specifying the |
| 451 | :option:`-i` option. |
| 452 | |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 453 | This variable can also be modified by Python code using :data:`os.environ` |
| 454 | to force inspect mode on program termination. |
| 455 | |
Georg Brandl | 59d121a | 2007-10-20 18:08:14 +0000 | [diff] [blame] | 456 | |
| 457 | .. envvar:: PYTHONUNBUFFERED |
| 458 | |
| 459 | If this is set to a non-empty string it is equivalent to specifying the |
| 460 | :option:`-u` option. |
| 461 | |
| 462 | |
| 463 | .. envvar:: PYTHONVERBOSE |
| 464 | |
| 465 | If this is set to a non-empty string it is equivalent to specifying the |
| 466 | :option:`-v` option. If set to an integer, it is equivalent to specifying |
| 467 | :option:`-v` multiple times. |
| 468 | |
| 469 | |
| 470 | .. envvar:: PYTHONCASEOK |
| 471 | |
| 472 | If this is set, Python ignores case in :keyword:`import` statements. This |
| 473 | only works on Windows. |
| 474 | |
Georg Brandl | 2da0fce | 2008-01-07 17:09:35 +0000 | [diff] [blame] | 475 | |
| 476 | .. envvar:: PYTHONDONTWRITEBYTECODE |
| 477 | |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 478 | If this is set, Python won't try to write ``.pyc`` or ``.pyo`` files on the |
Georg Brandl | 2da0fce | 2008-01-07 17:09:35 +0000 | [diff] [blame] | 479 | import of source modules. |
| 480 | |
| 481 | .. versionadded:: 2.6 |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 482 | |
Martin v. Löwis | 9981589 | 2008-06-01 07:20:46 +0000 | [diff] [blame] | 483 | .. envvar:: PYTHONIOENCODING |
| 484 | |
| 485 | Overrides the encoding used for stdin/stdout/stderr, in the syntax |
Georg Brandl | d987545 | 2008-06-11 17:57:44 +0000 | [diff] [blame] | 486 | ``encodingname:errorhandler``. The ``:errorhandler`` part is optional and |
| 487 | has the same meaning as in :func:`str.encode`. |
Martin v. Löwis | 9981589 | 2008-06-01 07:20:46 +0000 | [diff] [blame] | 488 | |
| 489 | .. versionadded:: 2.6 |
| 490 | |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 491 | |
Christian Heimes | af748c3 | 2008-05-06 22:41:46 +0000 | [diff] [blame] | 492 | .. envvar:: PYTHONNOUSERSITE |
| 493 | |
| 494 | If this is set, Python won't add the user site directory to sys.path |
| 495 | |
| 496 | .. versionadded:: 2.6 |
| 497 | |
| 498 | .. seealso:: |
| 499 | |
| 500 | :pep:`370` -- Per user site-packages directory |
| 501 | |
| 502 | |
| 503 | .. envvar:: PYTHONUSERBASE |
| 504 | |
| 505 | Sets the base directory for the user site directory |
| 506 | |
| 507 | .. versionadded:: 2.6 |
| 508 | |
| 509 | .. seealso:: |
| 510 | |
| 511 | :pep:`370` -- Per user site-packages directory |
| 512 | |
| 513 | |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 514 | .. envvar:: PYTHONEXECUTABLE |
| 515 | |
| 516 | If this environment variable is set, ``sys.argv[0]`` will be set to its |
| 517 | value instead of the value got through the C runtime. Only works on |
Georg Brandl | 9af9498 | 2008-09-13 17:41:16 +0000 | [diff] [blame] | 518 | Mac OS X. |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 519 | |
| 520 | |
| 521 | Debug-mode variables |
Georg Brandl | 61d2886 | 2008-01-07 18:57:03 +0000 | [diff] [blame] | 522 | ~~~~~~~~~~~~~~~~~~~~ |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 523 | |
| 524 | Setting these variables only has an effect in a debug build of Python, that is, |
Georg Brandl | 61d2886 | 2008-01-07 18:57:03 +0000 | [diff] [blame] | 525 | if Python was configured with the :option:`--with-pydebug` build option. |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 526 | |
| 527 | .. envvar:: PYTHONTHREADDEBUG |
| 528 | |
Nick Coghlan | 31f6315 | 2008-04-30 14:23:36 +0000 | [diff] [blame] | 529 | If set, Python will print threading debug info. |
Georg Brandl | aed6c66 | 2008-01-07 17:25:53 +0000 | [diff] [blame] | 530 | |
| 531 | .. versionchanged:: 2.6 |
| 532 | Previously, this variable was called ``THREADDEBUG``. |
| 533 | |
| 534 | .. envvar:: PYTHONDUMPREFS |
| 535 | |
| 536 | If set, Python will dump objects and reference counts still alive after |
| 537 | shutting down the interpreter. |
| 538 | |
| 539 | |
| 540 | .. envvar:: PYTHONMALLOCSTATS |
| 541 | |
| 542 | If set, Python will print memory allocation statistics every time a new |
| 543 | object arena is created, and on shutdown. |
| 544 | |