1PYTHON(1) General Commands Manual PYTHON(1)
2
6 python - an interpreted, interactive, object-oriented programming lan‐
7 guage
8
10 python [ -B ] [ -d ] [ -E ] [ -h ] [ -i ] [ -m module-name ]
11 [ -O ] [ -O0 ] [ -Q argument ] [ -s ] [ -S ] [ -t ] [ -u ]
12 [ -v ] [ -V ] [ -W argument ] [ -x ] [ -3 ] [ -? ]
13 [ -c command | script | - ] [ arguments ]
14
16 Python is an interpreted, interactive, object-oriented programming lan‐
17 guage that combines remarkable power with very clear syntax. For an
18 introduction to programming in Python you are referred to the Python
19 Tutorial. The Python Library Reference documents built-in and standard
20 types, constants, functions and modules. Finally, the Python Reference
21 Manual describes the syntax and semantics of the core language in (per‐
22 haps too) much detail. (These documents may be located via the INTER‐
23 NET RESOURCES below; they may be installed on your system as well.)
24 Python's basic power can be extended with your own modules written in C
26 or C++. On most systems such modules may be dynamically loaded.
27 Python is also adaptable as an extension language for existing applica‐
28 tions. See the internal documentation for hints.
29 Documentation for installed Python modules and packages can be viewed
31 by running the pydoc program.
32
34 -B Don't write .py[co] files on import. See also PYTHONDONTWRITE‐
35 BYTECODE.
36 -c command
38 Specify the command to execute (see next section). This termi‐
39 nates the option list (following options are passed as arguments
40 to the command).
41 -d Turn on parser debugging output (for wizards only, depending on
43 compilation options).
44 -E Ignore environment variables like PYTHONPATH and PYTHONHOME that
46 modify the behavior of the interpreter.
47 -h , -? , --help
49 Prints the usage for the interpreter executable and exits.
50 -i When a script is passed as first argument or the -c option is
52 used, enter interactive mode after executing the script or the
53 command. It does not read the $PYTHONSTARTUP file. This can be
54 useful to inspect global variables or a stack trace when a
55 script raises an exception.
56 -m module-name
58 Searches sys.path for the named module and runs the correspond‐
59 ing .py file as a script.
60 -O Turn on basic optimizations. This changes the filename exten‐
62 sion for compiled (bytecode) files from .pyc to .pyo. Given
63 twice, causes docstrings to be discarded.
64 -O0 Discard docstrings in addition to the -O optimizations.
66 -Q argument
68 Division control; see PEP 238. The argument must be one of
69 "old" (the default, int/int and long/long return an int or
70 long), "new" (new division semantics, i.e. int/int and long/long
71 returns a float), "warn" (old division semantics with a warning
72 for int/int and long/long), or "warnall" (old division semantics
73 with a warning for all use of the division operator). For a use
74 of "warnall", see the Tools/scripts/fixdiv.py script.
75 -s Don't add user site directory to sys.path.
77 -S Disable the import of the module site and the site-dependent
79 manipulations of sys.path that it entails.
80 -t Issue a warning when a source file mixes tabs and spaces for
82 indentation in a way that makes it depend on the worth of a tab
83 expressed in spaces. Issue an error when the option is given
84 twice.
85 -u Force stdin, stdout and stderr to be totally unbuffered. On
87 systems where it matters, also put stdin, stdout and stderr in
88 binary mode. Note that there is internal buffering in xread‐
89 lines(), readlines() and file-object iterators ("for line in
90 sys.stdin") which is not influenced by this option. To work
91 around this, you will want to use "sys.stdin.readline()" inside
92 a "while 1:" loop.
93 -v Print a message each time a module is initialized, showing the
95 place (filename or built-in module) from which it is loaded.
96 When given twice, print a message for each file that is checked
97 for when searching for a module. Also provides information on
98 module cleanup at exit.
99 -V , --version
101 Prints the Python version number of the executable and exits.
102 -W argument
104 Warning control. Python sometimes prints warning message to
105 sys.stderr. A typical warning message has the following form:
106 file:line: category: message. By default, each warning is
107 printed once for each source line where it occurs. This option
108 controls how often warnings are printed. Multiple -W options
109 may be given; when a warning matches more than one option, the
110 action for the last matching option is performed. Invalid -W
111 options are ignored (a warning message is printed about invalid
112 options when the first warning is issued). Warnings can also be
113 controlled from within a Python program using the warnings mod‐
114 ule.
115 The simplest form of argument is one of the following action
117 strings (or a unique abbreviation): ignore to ignore all warn‐
118 ings; default to explicitly request the default behavior (print‐
119 ing each warning once per source line); all to print a warning
120 each time it occurs (this may generate many messages if a warn‐
121 ing is triggered repeatedly for the same source line, such as
122 inside a loop); module to print each warning only the first time
123 it occurs in each module; once to print each warning only the
124 first time it occurs in the program; or error to raise an excep‐
125 tion instead of printing a warning message.
126 The full form of argument is action:message:category:mod‐
128 ule:line. Here, action is as explained above but only applies
129 to messages that match the remaining fields. Empty fields match
130 all values; trailing empty fields may be omitted. The message
131 field matches the start of the warning message printed; this
132 match is case-insensitive. The category field matches the warn‐
133 ing category. This must be a class name; the match test whether
134 the actual warning category of the message is a subclass of the
135 specified warning category. The full class name must be given.
136 The module field matches the (fully-qualified) module name; this
137 match is case-sensitive. The line field matches the line num‐
138 ber, where zero matches all line numbers and is thus equivalent
139 to an omitted line number.
140 -x Skip the first line of the source. This is intended for a DOS
142 specific hack only. Warning: the line numbers in error messages
143 will be off by one!
144 -3 Warn about Python 3.x incompatibilities that 2to3 cannot triv‐
146 ially fix.
147
149 The interpreter interface resembles that of the UNIX shell: when called
150 with standard input connected to a tty device, it prompts for commands
151 and executes them until an EOF is read; when called with a file name
152 argument or with a file as standard input, it reads and executes a
153 script from that file; when called with -c command, it executes the
154 Python statement(s) given as command. Here command may contain multi‐
155 ple statements separated by newlines. Leading whitespace is signifi‐
156 cant in Python statements! In non-interactive mode, the entire input
157 is parsed before it is executed.
158 If available, the script name and additional arguments thereafter are
160 passed to the script in the Python variable sys.argv , which is a list
161 of strings (you must first import sys to be able to access it). If no
162 script name is given, sys.argv[0] is an empty string; if -c is used,
163 sys.argv[0] contains the string '-c'. Note that options interpreted by
164 the Python interpreter itself are not placed in sys.argv.
165 In interactive mode, the primary prompt is `>>>'; the second prompt
167 (which appears when a command is not complete) is `...'. The prompts
168 can be changed by assignment to sys.ps1 or sys.ps2. The interpreter
169 quits when it reads an EOF at a prompt. When an unhandled exception
170 occurs, a stack trace is printed and control returns to the primary
171 prompt; in non-interactive mode, the interpreter exits after printing
172 the stack trace. The interrupt signal raises the KeyboardInterrupt
173 exception; other UNIX signals are not caught (except that SIGPIPE is
174 sometimes ignored, in favor of the IOError exception). Error messages
175 are written to stderr.
176
178 These are subject to difference depending on local installation conven‐
179 tions; ${prefix} and ${exec_prefix} are installation-dependent and
180 should be interpreted as for GNU software; they may be the same. The
181 default for both is /usr/local.
182 ${exec_prefix}/bin/python
184 Recommended location of the interpreter.
185 ${prefix}/lib/python<version>
187 ${exec_prefix}/lib/python<version>
188 Recommended locations of the directories containing the standard
189 modules.
190 ${prefix}/include/python<version>
192 ${exec_prefix}/include/python<version>
193 Recommended locations of the directories containing the include
194 files needed for developing Python extensions and embedding the
195 interpreter.
196 ~/.pythonrc.py
198 User-specific initialization file loaded by the user module; not
199 used by default or by most applications.
200
202 PYTHONHOME
203 Change the location of the standard Python libraries. By
204 default, the libraries are searched in ${prefix}/lib/python<ver‐
205 sion> and ${exec_prefix}/lib/python<version>, where ${prefix}
206 and ${exec_prefix} are installation-dependent directories, both
207 defaulting to /usr/local. When $PYTHONHOME is set to a single
208 directory, its value replaces both ${prefix} and ${exec_prefix}.
209 To specify different values for these, set $PYTHONHOME to ${pre‐
210 fix}:${exec_prefix}.
211 PYTHONPATH
213 Augments the default search path for module files. The format
214 is the same as the shell's $PATH: one or more directory path‐
215 names separated by colons. Non-existent directories are
216 silently ignored. The default search path is installation
217 dependent, but generally begins with ${prefix}/lib/python<ver‐
218 sion> (see PYTHONHOME above). The default search path is always
219 appended to $PYTHONPATH. If a script argument is given, the
220 directory containing the script is inserted in the path in front
221 of $PYTHONPATH. The search path can be manipulated from within
222 a Python program as the variable sys.path .
223 PYTHONSTARTUP
225 If this is the name of a readable file, the Python commands in
226 that file are executed before the first prompt is displayed in
227 interactive mode. The file is executed in the same name space
228 where interactive commands are executed so that objects defined
229 or imported in it can be used without qualification in the
230 interactive session. You can also change the prompts sys.ps1
231 and sys.ps2 in this file.
232 PYTHONY2K
234 Set this to a non-empty string to cause the time module to
235 require dates specified as strings to include 4-digit years,
236 otherwise 2-digit years are converted based on rules described
237 in the time module documentation.
238 PYTHONOPTIMIZE
240 If this is set to a non-empty string it is equivalent to speci‐
241 fying the -O option. If set to an integer, it is equivalent to
242 specifying -O multiple times.
243 PYTHONDEBUG
245 If this is set to a non-empty string it is equivalent to speci‐
246 fying the -d option. If set to an integer, it is equivalent to
247 specifying -d multiple times.
248 PYTHONDONTWRITEBYTECODE
250 If this is set to a non-empty string it is equivalent to speci‐
251 fying the -B option (don't try to write .py[co] files).
252 PYTHONINSPECT
254 If this is set to a non-empty string it is equivalent to speci‐
255 fying the -i option.
256 PYTHONNOUSERSITE
258 If this is set to a non-empty string it is equivalent to speci‐
259 fying the -s option (Don't add the user site directory to
260 sys.path).
261 PYTHONUNBUFFERED
263 If this is set to a non-empty string it is equivalent to speci‐
264 fying the -u option.
265 PYTHONVERBOSE
267 If this is set to a non-empty string it is equivalent to speci‐
268 fying the -v option. If set to an integer, it is equivalent to
269 specifying -v multiple times.
270 PYTHONWARNINGS
272 If this is set to a comma-separated string it is equivalent to
273 specifying the -W option for each separate value.
274
276 The Python Software Foundation: http://www.python.org/psf
277
279 Main website: http://www.python.org/
280 Documentation: http://docs.python.org/
281 Developer resources: http://www.python.org/dev/
282 Downloads: http://python.org/download/
283 Module repository: http://pypi.python.org/
284 Newsgroups: comp.lang.python, comp.lang.python.announce
285
287 Python is distributed under an Open Source license. See the file
288 "LICENSE" in the Python source distribution for information on terms &
289 conditions for accessing and otherwise using Python and for a DIS‐
290 CLAIMER OF ALL WARRANTIES.
291 $Date: 2010-04-06 18:38:57 -0500 (Tue, 06 Apr 2010) $ PYTHON(1)