1PYTHON(1) General Commands Manual PYTHON(1)
2
6 python - an interpreted, interactive, object-oriented programming lan‐
7 guage
8
10 python [ -d ] [ -E ] [ -h ] [ -i ] [ -m module-name ] [ -O ]
11 [ -Q argument ] [ -S ] [ -t ] [ -u ]
12 [ -v ] [ -V ] [ -W argument ] [ -x ]
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 -c command
35 Specify the command to execute (see next section). This termi‐
36 nates the option list (following options are passed as arguments
37 to the command).
38 -d Turn on parser debugging output (for wizards only, depending on
40 compilation options).
41 -E Ignore environment variables like PYTHONPATH and PYTHONHOME that
43 modify the behavior of the interpreter.
44 -h Prints the usage for the interpreter executable and exits.
46 -i When a script is passed as first argument or the -c option is
48 used, enter interactive mode after executing the script or the
49 command. It does not read the $PYTHONSTARTUP file. This can be
50 useful to inspect global variables or a stack trace when a
51 script raises an exception.
52 -m module-name
54 Searches sys.path for the named module and runs the correspond‐
55 ing .py file as a script.
56 -O Turn on basic optimizations. This changes the filename exten‐
58 sion for compiled (bytecode) files from .pyc to .pyo. Given
59 twice, causes docstrings to be discarded.
60 -Q argument
62 Division control; see PEP 238. The argument must be one of
63 "old" (the default, int/int and long/long return an int or
64 long), "new" (new division semantics, i.e. int/int and long/long
65 returns a float), "warn" (old division semantics with a warning
66 for int/int and long/long), or "warnall" (old division semantics
67 with a warning for all use of the division operator). For a use
68 of "warnall", see the Tools/scripts/fixdiv.py script.
69 -S Disable the import of the module site and the site-dependent
71 manipulations of sys.path that it entails.
72 -t Issue a warning when a source file mixes tabs and spaces for
74 indentation in a way that makes it depend on the worth of a tab
75 expressed in spaces. Issue an error when the option is given
76 twice.
77 -u Force stdin, stdout and stderr to be totally unbuffered. On
79 systems where it matters, also put stdin, stdout and stderr in
80 binary mode. Note that there is internal buffering in xread‐
81 lines(), readlines() and file-object iterators ("for line in
82 sys.stdin") which is not influenced by this option. To work
83 around this, you will want to use "sys.stdin.readline()" inside
84 a "while 1:" loop.
85 -v Print a message each time a module is initialized, showing the
87 place (filename or built-in module) from which it is loaded.
88 When given twice, print a message for each file that is checked
89 for when searching for a module. Also provides information on
90 module cleanup at exit.
91 -V Prints the Python version number of the executable and exits.
93 -W argument
95 Warning control. Python sometimes prints warning message to
96 sys.stderr. A typical warning message has the following form:
97 file:line: category: message. By default, each warning is
98 printed once for each source line where it occurs. This option
99 controls how often warnings are printed. Multiple -W options
100 may be given; when a warning matches more than one option, the
101 action for the last matching option is performed. Invalid -W
102 options are ignored (a warning message is printed about invalid
103 options when the first warning is issued). Warnings can also be
104 controlled from within a Python program using the warnings mod‐
105 ule.
106 The simplest form of argument is one of the following action
108 strings (or a unique abbreviation): ignore to ignore all warn‐
109 ings; default to explicitly request the default behavior (print‐
110 ing each warning once per source line); all to print a warning
111 each time it occurs (this may generate many messages if a warn‐
112 ing is triggered repeatedly for the same source line, such as
113 inside a loop); module to print each warning only only the first
114 time it occurs in each module; once to print each warning only
115 the first time it occurs in the program; or error to raise an
116 exception instead of printing a warning message.
117 The full form of argument is action:message:category:mod‐
119 ule:line. Here, action is as explained above but only applies
120 to messages that match the remaining fields. Empty fields match
121 all values; trailing empty fields may be omitted. The message
122 field matches the start of the warning message printed; this
123 match is case-insensitive. The category field matches the warn‐
124 ing category. This must be a class name; the match test whether
125 the actual warning category of the message is a subclass of the
126 specified warning category. The full class name must be given.
127 The module field matches the (fully-qualified) module name; this
128 match is case-sensitive. The line field matches the line num‐
129 ber, where zero matches all line numbers and is thus equivalent
130 to an omitted line number.
131 -x Skip the first line of the source. This is intended for a DOS
133 specific hack only. Warning: the line numbers in error messages
134 will be off by one!
135
137 The interpreter interface resembles that of the UNIX shell: when called
138 with standard input connected to a tty device, it prompts for commands
139 and executes them until an EOF is read; when called with a file name
140 argument or with a file as standard input, it reads and executes a
141 script from that file; when called with -c command, it executes the
142 Python statement(s) given as command. Here command may contain multi‐
143 ple statements separated by newlines. Leading whitespace is signifi‐
144 cant in Python statements! In non-interactive mode, the entire input
145 is parsed before it is executed.
146 If available, the script name and additional arguments thereafter are
148 passed to the script in the Python variable sys.argv , which is a list
149 of strings (you must first import sys to be able to access it). If no
150 script name is given, sys.argv[0] is an empty string; if -c is used,
151 sys.argv[0] contains the string '-c'. Note that options interpreted by
152 the Python interpreter itself are not placed in sys.argv.
153 In interactive mode, the primary prompt is `>>>'; the second prompt
155 (which appears when a command is not complete) is `...'. The prompts
156 can be changed by assignment to sys.ps1 or sys.ps2. The interpreter
157 quits when it reads an EOF at a prompt. When an unhandled exception
158 occurs, a stack trace is printed and control returns to the primary
159 prompt; in non-interactive mode, the interpreter exits after printing
160 the stack trace. The interrupt signal raises the KeyboardInterrupt
161 exception; other UNIX signals are not caught (except that SIGPIPE is
162 sometimes ignored, in favor of the IOError exception). Error messages
163 are written to stderr.
164
166 These are subject to difference depending on local installation conven‐
167 tions; ${prefix} and ${exec_prefix} are installation-dependent and
168 should be interpreted as for GNU software; they may be the same. The
169 default for both is /usr/local.
170 ${exec_prefix}/bin/python
172 Recommended location of the interpreter.
173 ${prefix}/lib/python<version>
175 ${exec_prefix}/lib/python<version>
176 Recommended locations of the directories containing the standard
177 modules.
178 ${prefix}/include/python<version>
180 ${exec_prefix}/include/python<version>
181 Recommended locations of the directories containing the include
182 files needed for developing Python extensions and embedding the
183 interpreter.
184 ~/.pythonrc.py
186 User-specific initialization file loaded by the user module; not
187 used by default or by most applications.
188
190 PYTHONHOME
191 Change the location of the standard Python libraries. By
192 default, the libraries are searched in ${prefix}/lib/python<ver‐
193 sion> and ${exec_prefix}/lib/python<version>, where ${prefix}
194 and ${exec_prefix} are installation-dependent directories, both
195 defaulting to /usr/local. When $PYTHONHOME is set to a single
196 directory, its value replaces both ${prefix} and ${exec_prefix}.
197 To specify different values for these, set $PYTHONHOME to ${pre‐
198 fix}:${exec_prefix}.
199 PYTHONPATH
201 Augments the default search path for module files. The format
202 is the same as the shell's $PATH: one or more directory path‐
203 names separated by colons. Non-existent directories are
204 silently ignored. The default search path is installation
205 dependent, but generally begins with ${prefix}/lib/python<ver‐
206 sion> (see PYTHONHOME above). The default search path is always
207 appended to $PYTHONPATH. If a script argument is given, the
208 directory containing the script is inserted in the path in front
209 of $PYTHONPATH. The search path can be manipulated from within
210 a Python program as the variable sys.path .
211 PYTHONSTARTUP
213 If this is the name of a readable file, the Python commands in
214 that file are executed before the first prompt is displayed in
215 interactive mode. The file is executed in the same name space
216 where interactive commands are executed so that objects defined
217 or imported in it can be used without qualification in the
218 interactive session. You can also change the prompts sys.ps1
219 and sys.ps2 in this file.
220 PYTHONY2K
222 Set this to a non-empty string to cause the time module to
223 require dates specified as strings to include 4-digit years,
224 otherwise 2-digit years are converted based on rules described
225 in the time module documentation.
226 PYTHONOPTIMIZE
228 If this is set to a non-empty string it is equivalent to speci‐
229 fying the -O option. If set to an integer, it is equivalent to
230 specifying -O multiple times.
231 PYTHONDEBUG
233 If this is set to a non-empty string it is equivalent to speci‐
234 fying the -d option. If set to an integer, it is equivalent to
235 specifying -d multiple times.
236 PYTHONINSPECT
238 If this is set to a non-empty string it is equivalent to speci‐
239 fying the -i option.
240 PYTHONUNBUFFERED
242 If this is set to a non-empty string it is equivalent to speci‐
243 fying the -u option.
244 PYTHONVERBOSE
246 If this is set to a non-empty string it is equivalent to speci‐
247 fying the -v option. If set to an integer, it is equivalent to
248 specifying -v multiple times.
249
251 The Python Software Foundation: http://www.python.org/psf
252
254 Main website: http://www.python.org/
255 Documentation: http://docs.python.org/
256 Community website: http://starship.python.net/
257 Developer resources: http://www.python.org/dev/
258 FTP: ftp://ftp.python.org/pub/python/
259 Module repository: http://www.vex.net/parnassus/
260 Newsgroups: comp.lang.python, comp.lang.python.announce
261
263 Python is distributed under an Open Source license. See the file
264 "LICENSE" in the Python source distribution for information on terms &
265 conditions for accessing and otherwise using Python and for a DIS‐
266 CLAIMER OF ALL WARRANTIES.
267 $Date: 2005-03-21 01:16:03 +1100 (Mon, 21 Mar 2005) $ PYTHON(1)