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<H1><A NAME="SECTION004000000000000000000"></A><A NAME="using"></A>
<BR>
2. Using the Python Interpreter 
</H1>

<P>

<H1><A NAME="SECTION004100000000000000000"></A><A NAME="invoking"></A>
<BR>
2.1 Invoking the Interpreter 
</H1>

<P>
The Python interpreter is usually installed as
<span class="file">/usr/local/bin/python</span> on those machines where it is available;
putting <span class="file">/usr/local/bin</span> in your <span class="Unix">Unix</span> shell's search path
makes it possible to start it by typing the command

<P>
<div class="verbatim"><pre>
python
</pre></div>

<P>
to the shell.  Since the choice of the directory where the interpreter
lives is an installation option, other places are possible; check with
your local Python guru or system administrator.  (E.g.,
<span class="file">/usr/local/python</span> is a popular alternative location.)

<P>
Typing an end-of-file character (<kbd>Control-D</kbd> on <span class="Unix">Unix</span>,
<kbd>Control-Z</kbd> on Windows) at the primary prompt causes the
interpreter to exit with a zero exit status.  If that doesn't work,
you can exit the interpreter by typing the following commands:
"<tt class="samp">import sys; sys.exit()</tt>".

<P>
The interpreter's line-editing features usually aren't very
sophisticated.  On <span class="Unix">Unix</span>, whoever installed the interpreter may have
enabled support for the GNU readline library, which adds more
elaborate interactive editing and history features. Perhaps the
quickest check to see whether command line editing is supported is
typing Control-P to the first Python prompt you get.  If it beeps, you
have command line editing; see Appendix <A HREF="node15.html#interacting">A</A> for an
introduction to the keys.  If nothing appears to happen, or if
<code>P</code> is echoed, command line editing isn't available; you'll
only be able to use backspace to remove characters from the current
line.

<P>
The interpreter operates somewhat like the <span class="Unix">Unix</span> shell: when called
with standard input connected to a tty device, it reads and executes
commands interactively; when called with a file name argument or with
a file as standard input, it reads and executes a <em>script</em> from
that file. 

<P>
A second way of starting the interpreter is
"<tt class="samp"><b class="program">python</b> <b class="programopt">-c</b> <var>command</var> [arg] ...</tt>", which
executes the statement(s) in <var>command</var>, analogous to the shell's
<b class="programopt">-c</b> option.  Since Python statements often contain spaces
or other characters that are special to the shell, it is best to quote 
<var>command</var> in its entirety with double quotes.

<P>
Some Python modules are also useful as scripts.  These can be invoked using
"<tt class="samp"><b class="program">python</b> <b class="programopt">-m</b> <var>module</var> [arg] ...</tt>", which
executes the source file for <var>module</var> as if you had spelled out its
full name on the command line.

<P>
Note that there is a difference between "<tt class="samp">python file</tt>" and
"<tt class="samp">python &lt;file</tt>".  In the latter case, input requests from the
program, such as calls to <tt class="function">input()</tt> and <tt class="function">raw_input()</tt>, are
satisfied from <em>file</em>.  Since this file has already been read
until the end by the parser before the program starts executing, the
program will encounter end-of-file immediately.  In the former case
(which is usually what you want) they are satisfied from whatever file
or device is connected to standard input of the Python interpreter.

<P>
When a script file is used, it is sometimes useful to be able to run
the script and enter interactive mode afterwards.  This can be done by
passing <b class="programopt">-i</b> before the script.  (This does not work if the
script is read from standard input, for the same reason as explained
in the previous paragraph.)

<P>

<H2><A NAME="SECTION004110000000000000000"></A><A NAME="argPassing"></A>
<BR>
2.1.1 Argument Passing 
</H2>

<P>
When known to the interpreter, the script name and additional
arguments thereafter are passed to the script in the variable
<code>sys.argv</code>, which is a list of strings.  Its length is at least
one; when no script and no arguments are given, <code>sys.argv[0]</code> is
an empty string.  When the script name is given as <code>'-'</code> (meaning 
standard input), <code>sys.argv[0]</code> is set to <code>'-'</code>.  When
<b class="programopt">-c</b> <var>command</var> is used, <code>sys.argv[0]</code> is set to
<code>'-c'</code>.  When <b class="programopt">-m</b> <var>module</var> is used, <code>sys.argv[0]</code> 
is set to the full name of the located module.  Options found after 
<b class="programopt">-c</b> <var>command</var> or <b class="programopt">-m</b> <var>module</var> are not consumed 
by the Python interpreter's option processing but left in <code>sys.argv</code> for 
the command or module to handle.

<P>

<H2><A NAME="SECTION004120000000000000000"></A><A NAME="interactive"></A>
<BR>
2.1.2 Interactive Mode 
</H2>

<P>
When commands are read from a tty, the interpreter is said to be in
<em>interactive mode</em>.  In this mode it prompts for the next command
with the <em>primary prompt</em>, usually three greater-than signs
("<tt class="samp">&gt;<code>&gt;</code>&gt;&nbsp;</tt>"); for continuation lines it prompts with the
<em>secondary prompt</em>, by default three dots ("<tt class="samp">...&nbsp;</tt>").
The interpreter prints a welcome message stating its version number
and a copyright notice before printing the first prompt:

<P>
<div class="verbatim"><pre>
python
Python 1.5.2b2 (#1, Feb 28 1999, 00:02:06)  [GCC 2.8.1] on sunos5
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
&gt;&gt;&gt;
</pre></div>

<P>
Continuation lines are needed when entering a multi-line construct.
As an example, take a look at this <tt class="keyword">if</tt> statement:

<P>
<div class="verbatim"><pre>
&gt;&gt;&gt; the_world_is_flat = 1
&gt;&gt;&gt; if the_world_is_flat:
...     print "Be careful not to fall off!"
... 
Be careful not to fall off!
</pre></div>

<P>

<H1><A NAME="SECTION004200000000000000000"></A><A NAME="interp"></A>
<BR>
2.2 The Interpreter and Its Environment 
</H1>

<P>

<H2><A NAME="SECTION004210000000000000000"></A><A NAME="error"></A>
<BR>
2.2.1 Error Handling 
</H2>

<P>
When an error occurs, the interpreter prints an error
message and a stack trace.  In interactive mode, it then returns to
the primary prompt; when input came from a file, it exits with a
nonzero exit status after printing
the stack trace.  (Exceptions handled by an <tt class="keyword">except</tt> clause in a
<tt class="keyword">try</tt> statement are not errors in this context.)  Some errors are
unconditionally fatal and cause an exit with a nonzero exit; this
applies to internal inconsistencies and some cases of running out of
memory.  All error messages are written to the standard error stream;
normal output from executed commands is written to standard
output.

<P>
Typing the interrupt character (usually Control-C or DEL) to the
primary or secondary prompt cancels the input and returns to the
primary prompt.<A NAME="tex2html1"
  HREF="#foot123"><SUP>2.1</SUP></A>Typing an interrupt while a command is executing raises the
<tt class="exception">KeyboardInterrupt</tt> exception, which may be handled by a
<tt class="keyword">try</tt> statement.

<P>

<H2><A NAME="SECTION004220000000000000000"></A><A NAME="scripts"></A>
<BR>
2.2.2 Executable Python Scripts 
</H2>

<P>
On BSD'ish <span class="Unix">Unix</span> systems, Python scripts can be made directly
executable, like shell scripts, by putting the line

<P>
<div class="verbatim"><pre>
#! /usr/bin/env python
</pre></div>

<P>
(assuming that the interpreter is on the user's <a class="envvar" id='l2h-1' xml:id='l2h-1'>PATH</a>) at the
beginning of the script and giving the file an executable mode.  The
"<tt class="samp">#!</tt>" must be the first two characters of the file.  On some
platforms, this first line must end with a <span class="Unix">Unix</span>-style line ending
("<tt class="character">&#92;n</tt>"), not a Mac OS ("<tt class="character">&#92;r</tt>") or Windows
("<tt class="character">&#92;r&#92;n</tt>") line ending.  Note that
the hash, or pound, character, "<tt class="character">#</tt>", is used to start a
comment in Python.

<P>
The script can be given a executable mode, or permission, using the
<b class="program">chmod</b> command:

<P>
<div class="verbatim"><pre>
$ chmod +x myscript.py
</pre></div> 
<P>

<H2><A NAME="SECTION004230000000000000000">
2.2.3 Source Code Encoding</A>
</H2>

<P>
It is possible to use encodings different than ASCII in Python source
files. The best way to do it is to put one more special comment line
right after the <code>#!</code> line to define the source file encoding:

<P>
<div class="verbatim"><pre><TT>
 # -*- coding: <var>encoding</var> -*- 
 </TT></pre></div>

<P>
With that declaration, all characters in the source file will be treated as
having the encoding <var>encoding</var>, and it will be
possible to directly write Unicode string literals in the selected
encoding.  The list of possible encodings can be found in the
<em class="citetitle"><a
 href="../lib/lib.html"
 title="Python Library Reference"
 >Python Library Reference</a></em>, in the section
on <a class="ulink" href="../lib/module-codecs.html"
  ><tt class="module">codecs</tt></a>.

<P>
For example, to write Unicode literals including the Euro currency
symbol, the ISO-8859-15 encoding can be used, with the Euro symbol
having the ordinal value 164.  This script will print the value 8364
(the Unicode codepoint corresponding to the Euro symbol) and then
exit:

<P>
<div class="verbatim"><pre><TT>
 # -*- coding: iso-8859-15 -*-
 
 currency = u&#34;&#8364;&#34;
 print ord(currency)
 </TT></pre></div>

<P>
If your editor supports saving files as <code>UTF-8</code> with a UTF-8
<em>byte order mark</em> (aka BOM), you can use that instead of an
encoding declaration. IDLE supports this capability if
<code>Options/General/Default Source Encoding/UTF-8</code> is set. Notice
that this signature is not understood in older Python releases (2.2
and earlier), and also not understood by the operating system for
script files with <code>#!</code> lines (only used on <span class="Unix">Unix</span> systems).

<P>
By using UTF-8 (either through the signature or an encoding
declaration), characters of most languages in the world can be used
simultaneously in string literals and comments.  Using non-ASCII
characters in identifiers is not supported. To display all these
characters properly, your editor must recognize that the file is
UTF-8, and it must use a font that supports all the characters in the
file.

<P>

<H2><A NAME="SECTION004240000000000000000"></A><A NAME="startup"></A>
<BR>
2.2.4 The Interactive Startup File 
</H2>

<P>
When you use Python interactively, it is frequently handy to have some
standard commands executed every time the interpreter is started.  You
can do this by setting an environment variable named
<a class="envvar" id='l2h-2' xml:id='l2h-2'>PYTHONSTARTUP</a> to the name of a file containing your start-up
commands.  This is similar to the <span class="file">.profile</span> feature of the
<span class="Unix">Unix</span> shells.

<P>
This file is only read in interactive sessions, not when Python reads
commands from a script, and not when <span class="file">/dev/tty</span> is given as the
explicit source of commands (which otherwise behaves like an
interactive session).  It is executed in the same namespace where
interactive commands are executed, so that objects that it defines or
imports can be used without qualification in the interactive session.
You can also change the prompts <code>sys.ps1</code> and <code>sys.ps2</code> in
this file.

<P>
If you want to read an additional start-up file from the current
directory, you can program this in the global start-up file using code
like "<tt class="samp">if os.path.isfile('.pythonrc.py'):
execfile('.pythonrc.py')</tt>".  If you want to use the startup file in a
script, you must do this explicitly in the script:

<P>
<div class="verbatim"><pre>
import os
filename = os.environ.get('PYTHONSTARTUP')
if filename and os.path.isfile(filename):
    execfile(filename)
</pre></div>

<P>
<BR><HR><H4>Footnotes</H4>
<DL>
<DT><A NAME="foot123">... prompt.</A><A
 HREF="node4.html#tex2html1"><SUP>2.1</SUP></A></DT>
<DD>
        A problem with the GNU Readline package may prevent this.


</DD>
</DL>
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66	<LI><A href="node4.html#SECTION004210000000000000000">2.2.1 Error Handling</a>
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74
75	<H1><A NAME="SECTION004000000000000000000"></A><A NAME="using"></A>
76	<BR>
77	2. Using the Python Interpreter
78	</H1>
79
80	<P>
81
82	<H1><A NAME="SECTION004100000000000000000"></A><A NAME="invoking"></A>
83	<BR>
84	2.1 Invoking the Interpreter
85	</H1>
86
87	<P>
88	The Python interpreter is usually installed as
89	<span class="file">/usr/local/bin/python</span> on those machines where it is available;
90	putting <span class="file">/usr/local/bin</span> in your <span class="Unix">Unix</span> shell's search path
91	makes it possible to start it by typing the command
92
93	<P>
94	<div class="verbatim"><pre>
95	python
96	</pre></div>
97
98	<P>
99	to the shell. Since the choice of the directory where the interpreter
100	lives is an installation option, other places are possible; check with
101	your local Python guru or system administrator. (E.g.,
102	<span class="file">/usr/local/python</span> is a popular alternative location.)
103
104	<P>
105	Typing an end-of-file character (<kbd>Control-D</kbd> on <span class="Unix">Unix</span>,
106	<kbd>Control-Z</kbd> on Windows) at the primary prompt causes the
107	interpreter to exit with a zero exit status. If that doesn't work,
108	you can exit the interpreter by typing the following commands:
109	"<tt class="samp">import sys; sys.exit()</tt>".
110
111	<P>
112	The interpreter's line-editing features usually aren't very
113	sophisticated. On <span class="Unix">Unix</span>, whoever installed the interpreter may have
114	enabled support for the GNU readline library, which adds more
115	elaborate interactive editing and history features. Perhaps the
116	quickest check to see whether command line editing is supported is
117	typing Control-P to the first Python prompt you get. If it beeps, you
118	have command line editing; see Appendix <A HREF="node15.html#interacting">A</A> for an
119	introduction to the keys. If nothing appears to happen, or if
120	<code>P</code> is echoed, command line editing isn't available; you'll
121	only be able to use backspace to remove characters from the current
122	line.
123
124	<P>
125	The interpreter operates somewhat like the <span class="Unix">Unix</span> shell: when called
126	with standard input connected to a tty device, it reads and executes
127	commands interactively; when called with a file name argument or with
128	a file as standard input, it reads and executes a <em>script</em> from
129	that file.
130
131	<P>
132	A second way of starting the interpreter is
133	"<tt class="samp"><b class="program">python</b> <b class="programopt">-c</b> <var>command</var> [arg] ...</tt>", which
134	executes the statement(s) in <var>command</var>, analogous to the shell's
135	<b class="programopt">-c</b> option. Since Python statements often contain spaces
136	or other characters that are special to the shell, it is best to quote
137	<var>command</var> in its entirety with double quotes.
138
139	<P>
140	Some Python modules are also useful as scripts. These can be invoked using
141	"<tt class="samp"><b class="program">python</b> <b class="programopt">-m</b> <var>module</var> [arg] ...</tt>", which
142	executes the source file for <var>module</var> as if you had spelled out its
143	full name on the command line.
144
145	<P>
146	Note that there is a difference between "<tt class="samp">python file</tt>" and
147	"<tt class="samp">python <file</tt>". In the latter case, input requests from the
148	program, such as calls to <tt class="function">input()</tt> and <tt class="function">raw_input()</tt>, are
149	satisfied from <em>file</em>. Since this file has already been read
150	until the end by the parser before the program starts executing, the
151	program will encounter end-of-file immediately. In the former case
152	(which is usually what you want) they are satisfied from whatever file
153	or device is connected to standard input of the Python interpreter.
154
155	<P>
156	When a script file is used, it is sometimes useful to be able to run
157	the script and enter interactive mode afterwards. This can be done by
158	passing <b class="programopt">-i</b> before the script. (This does not work if the
159	script is read from standard input, for the same reason as explained
160	in the previous paragraph.)
161
162	<P>
163
164	<H2><A NAME="SECTION004110000000000000000"></A><A NAME="argPassing"></A>
165	<BR>
166	2.1.1 Argument Passing
167	</H2>
168
169	<P>
170	When known to the interpreter, the script name and additional
171	arguments thereafter are passed to the script in the variable
172	<code>sys.argv</code>, which is a list of strings. Its length is at least
173	one; when no script and no arguments are given, <code>sys.argv[0]</code> is
174	an empty string. When the script name is given as <code>'-'</code> (meaning
175	standard input), <code>sys.argv[0]</code> is set to <code>'-'</code>. When
176	<b class="programopt">-c</b> <var>command</var> is used, <code>sys.argv[0]</code> is set to
177	<code>'-c'</code>. When <b class="programopt">-m</b> <var>module</var> is used, <code>sys.argv[0]</code>
178	is set to the full name of the located module. Options found after
179	<b class="programopt">-c</b> <var>command</var> or <b class="programopt">-m</b> <var>module</var> are not consumed
180	by the Python interpreter's option processing but left in <code>sys.argv</code> for
181	the command or module to handle.
182
183	<P>
184
185	<H2><A NAME="SECTION004120000000000000000"></A><A NAME="interactive"></A>
186	<BR>
187	2.1.2 Interactive Mode
188	</H2>
189
190	<P>
191	When commands are read from a tty, the interpreter is said to be in
192	<em>interactive mode</em>. In this mode it prompts for the next command
193	with the <em>primary prompt</em>, usually three greater-than signs
194	("<tt class="samp">><code>></code>> </tt>"); for continuation lines it prompts with the
195	<em>secondary prompt</em>, by default three dots ("<tt class="samp">... </tt>").
196	The interpreter prints a welcome message stating its version number
197	and a copyright notice before printing the first prompt:
198
199	<P>
200	<div class="verbatim"><pre>
201	python
202	Python 1.5.2b2 (#1, Feb 28 1999, 00:02:06) [GCC 2.8.1] on sunos5
203	Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
204	>>>
205	</pre></div>
206
207	<P>
208	Continuation lines are needed when entering a multi-line construct.
209	As an example, take a look at this <tt class="keyword">if</tt> statement:
210
211	<P>
212	<div class="verbatim"><pre>
213	>>> the_world_is_flat = 1
214	>>> if the_world_is_flat:
215	... print "Be careful not to fall off!"
216	...
217	Be careful not to fall off!
218	</pre></div>
219
220	<P>
221
222	<H1><A NAME="SECTION004200000000000000000"></A><A NAME="interp"></A>
223	<BR>
224	2.2 The Interpreter and Its Environment
225	</H1>
226
227	<P>
228
229	<H2><A NAME="SECTION004210000000000000000"></A><A NAME="error"></A>
230	<BR>
231	2.2.1 Error Handling
232	</H2>
233
234	<P>
235	When an error occurs, the interpreter prints an error
236	message and a stack trace. In interactive mode, it then returns to
237	the primary prompt; when input came from a file, it exits with a
238	nonzero exit status after printing
239	the stack trace. (Exceptions handled by an <tt class="keyword">except</tt> clause in a
240	<tt class="keyword">try</tt> statement are not errors in this context.) Some errors are
241	unconditionally fatal and cause an exit with a nonzero exit; this
242	applies to internal inconsistencies and some cases of running out of
243	memory. All error messages are written to the standard error stream;
244	normal output from executed commands is written to standard
245	output.
246
247	<P>
248	Typing the interrupt character (usually Control-C or DEL) to the
249	primary or secondary prompt cancels the input and returns to the
250	primary prompt.<A NAME="tex2html1"
251	HREF="#foot123"><SUP>2.1</SUP></A>Typing an interrupt while a command is executing raises the
252	<tt class="exception">KeyboardInterrupt</tt> exception, which may be handled by a
253	<tt class="keyword">try</tt> statement.
254
255	<P>
256
257	<H2><A NAME="SECTION004220000000000000000"></A><A NAME="scripts"></A>
258	<BR>
259	2.2.2 Executable Python Scripts
260	</H2>
261
262	<P>
263	On BSD'ish <span class="Unix">Unix</span> systems, Python scripts can be made directly
264	executable, like shell scripts, by putting the line
265
266	<P>
267	<div class="verbatim"><pre>
268	#! /usr/bin/env python
269	</pre></div>
270
271	<P>
272	(assuming that the interpreter is on the user's <a class="envvar" id='l2h-1' xml:id='l2h-1'>PATH</a>) at the
273	beginning of the script and giving the file an executable mode. The
274	"<tt class="samp">#!</tt>" must be the first two characters of the file. On some
275	platforms, this first line must end with a <span class="Unix">Unix</span>-style line ending
276	("<tt class="character">\n</tt>"), not a Mac OS ("<tt class="character">\r</tt>") or Windows
277	("<tt class="character">\r\n</tt>") line ending. Note that
278	the hash, or pound, character, "<tt class="character">#</tt>", is used to start a
279	comment in Python.
280
281	<P>
282	The script can be given a executable mode, or permission, using the
283	<b class="program">chmod</b> command:
284
285	<P>
286	<div class="verbatim"><pre>
287	$ chmod +x myscript.py
288	</pre></div>
289	<P>
290
291	<H2><A NAME="SECTION004230000000000000000">
292	2.2.3 Source Code Encoding</A>
293	</H2>
294
295	<P>
296	It is possible to use encodings different than ASCII in Python source
297	files. The best way to do it is to put one more special comment line
298	right after the <code>#!</code> line to define the source file encoding:
299
300	<P>
301	<div class="verbatim"><pre><TT>
302	# -- coding: <var>encoding</var> --
303	</TT></pre></div>
304
305	<P>
306	With that declaration, all characters in the source file will be treated as
307	having the encoding <var>encoding</var>, and it will be
308	possible to directly write Unicode string literals in the selected
309	encoding. The list of possible encodings can be found in the
310	<em class="citetitle"><a
311	href="../lib/lib.html"
312	title="Python Library Reference"
313	>Python Library Reference</a></em>, in the section
314	on <a class="ulink" href="../lib/module-codecs.html"
315	><tt class="module">codecs</tt></a>.
316
317	<P>
318	For example, to write Unicode literals including the Euro currency
319	symbol, the ISO-8859-15 encoding can be used, with the Euro symbol
320	having the ordinal value 164. This script will print the value 8364
321	(the Unicode codepoint corresponding to the Euro symbol) and then
322	exit:
323
324	<P>
325	<div class="verbatim"><pre><TT>
326	# -- coding: iso-8859-15 --
327
328	currency = u"€"
329	print ord(currency)
330	</TT></pre></div>
331
332	<P>
333	If your editor supports saving files as <code>UTF-8</code> with a UTF-8
334	<em>byte order mark</em> (aka BOM), you can use that instead of an
335	encoding declaration. IDLE supports this capability if
336	<code>Options/General/Default Source Encoding/UTF-8</code> is set. Notice
337	that this signature is not understood in older Python releases (2.2
338	and earlier), and also not understood by the operating system for
339	script files with <code>#!</code> lines (only used on <span class="Unix">Unix</span> systems).
340
341	<P>
342	By using UTF-8 (either through the signature or an encoding
343	declaration), characters of most languages in the world can be used
344	simultaneously in string literals and comments. Using non-ASCII
345	characters in identifiers is not supported. To display all these
346	characters properly, your editor must recognize that the file is
347	UTF-8, and it must use a font that supports all the characters in the
348	file.
349
350	<P>
351
352	<H2><A NAME="SECTION004240000000000000000"></A><A NAME="startup"></A>
353	<BR>
354	2.2.4 The Interactive Startup File
355	</H2>
356
357	<P>
358	When you use Python interactively, it is frequently handy to have some
359	standard commands executed every time the interpreter is started. You
360	can do this by setting an environment variable named
361	<a class="envvar" id='l2h-2' xml:id='l2h-2'>PYTHONSTARTUP</a> to the name of a file containing your start-up
362	commands. This is similar to the <span class="file">.profile</span> feature of the
363	<span class="Unix">Unix</span> shells.
364
365	<P>
366	This file is only read in interactive sessions, not when Python reads
367	commands from a script, and not when <span class="file">/dev/tty</span> is given as the
368	explicit source of commands (which otherwise behaves like an
369	interactive session). It is executed in the same namespace where
370	interactive commands are executed, so that objects that it defines or
371	imports can be used without qualification in the interactive session.
372	You can also change the prompts <code>sys.ps1</code> and <code>sys.ps2</code> in
373	this file.
374
375	<P>
376	If you want to read an additional start-up file from the current
377	directory, you can program this in the global start-up file using code
378	like "<tt class="samp">if os.path.isfile('.pythonrc.py'):
379	execfile('.pythonrc.py')</tt>". If you want to use the startup file in a
380	script, you must do this explicitly in the script:
381
382	<P>
383	<div class="verbatim"><pre>
384	import os
385	filename = os.environ.get('PYTHONSTARTUP')
386	if filename and os.path.isfile(filename):
387	execfile(filename)
388	</pre></div>
389
390	<P>
391	<BR><HR><H4>Footnotes</H4>
392	<DL>
393	<DT><A NAME="foot123">... prompt.</A><A
394	HREF="node4.html#tex2html1"><SUP>2.1</SUP></A></DT>
395	<DD>
396	A problem with the GNU Readline package may prevent this.
397
398
399	</DD>
400	</DL>
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