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  $XTermId: xterm.faq.html,v 1.84 2004/07/13 21:47:03 tom Exp $
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<HEAD>
<TITLE>XTERM - Frequently Asked Questions (FAQ)</TITLE>
<LINK REV=MADE HREF="mailto:dickey@invisible-island.net">
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Copyright 1997-2003,2004 by Thomas E. Dickey
<HR>
<H1>Contents</H1>
<UL>
<LI><A HREF="#what_is_it">What is XTERM?</A>
<LI><A HREF="#who_did_it">Who wrote XTERM?</A>
<LI><A HREF="#what_platforms">What platforms does it run on?</A>
<LI><A HREF="#latest_version">What is the latest version?</A>
<LI><A HREF="#other_versions">What versions are available?</A>
<LI><A HREF="#how_do_i">How do I ...</A>
<LI><A HREF="#frequent_problems">Frequent problems</A>
<LI><A HREF="#known_bugs">Known Bugs in XTERM</A>
<LI><A HREF="#building_it">How do I build XTERM?</A>
<LI><A HREF="#report_bugs">How do I report bugs?</A>
<LI><A HREF="#more_info">Additional Information</A>
<LI><A HREF="#future_work">Ongoing/future work</A>
</UL>

<HR>
<H1><A NAME="what_is_it">What is XTERM?</A></H1>
From the manual page:
<blockquote>
The xterm program is a terminal emulator for the X Window System.  It provides
DEC VT102 and Tektronix 4014 compatible terminals for programs that can't use
the window system directly.  If the underlying operating system supports
terminal resizing capabilities (for example, the SIGWINCH signal in systems
derived from 4.3bsd), xterm will use the facilities to notify programs running
in the window whenever it is resized.
</blockquote>

<H1><A NAME="who_did_it">Who wrote XTERM?</A></H1>
I've been working on xterm since early 1996
(see my <a href="xterm.log.html">changelog</a> for details).
<P>
But the program is much older than that.
<p>
A lot of people, cited at the bottom of the manual page wrote
the original xterm program, maintained by the X Consortium
(later part of the Open Group - I'm well aware of the distinction,
but am citing when the work was done, not who the current owner may be).
There is no changelog, and it is not clear who did what.
Email from Jim Gettys provides some background:
<blockquote>
Cast of thousands...
<p>
To give a bit of history, xterm predates X!
<p>
It was originally written as a stand-alone terminal emulator for the
VS100 by Mark Vandevoorde, as my coop student the summer that
X started.
<p>
Part way through the summer, it became clear that X was more useful
than trying to do a stand alone program, so I had him retarget it to X.
Part of why xterm's internals are so horrifying is that it was originally
intended that a single process be able to drive multiple VS100 displays.
Don't hold this against Mark; it isn't his fault.
<p>
I then did a lot of hacking on it, and merged several improved versions
from others back in.
<p>
Notable improvements include the proper ANSI parser, that Bob McNamara
did.
<p>
The Tek 4010 support came from a guy at Smithsonian Astrophysical Observatory
whose name slips my mind at the moment.
<p>
Ported to X11 by Loretta Guarino.
<p>
Then hacked on at the X Consortium by uncounted people.
</blockquote>
Email from Doug Mink provides more background:
<blockquote>
I was checking out the newly revised AltaVista search
engine to see what was on the net about xterm, and I
found your pages.  I can add to the FAQ in that I was the
"guy at the Smithsonian Astrophysical Observatory" Jim
Gettys refers to.  I am listed at the end of the man page
under authors.  What happened was that I was hired by SAO
(after leaving the research staff at MIT) in October 1985
to write analysis software for the Spacelab 2 Infrared
Telescope which was to fly on the Space Shuttle in 1985
less than six months after I was hired.  I came with a tar
tape full of software I had written for Unix and Tektronix
terminals, but I was presented with a VS100 terminal which
had an early version (X6 or so) of xterm, with no graphics
capabilities.  SAO is at Harvard, across Cambridge from MIT,
where Jim Gettys was detailed from DEC to the X project,
and Jim had connections with SAO, having worked here after
college (MIT, where we had both worked at the observatory
at various times); he was still sharing an apartment with
an SAO colleague of mine, too. Anyway, everyone decided
that since I knew Tektronix commands pretty well, and our
group desparately needed the graphics capabilities, it
would be a good use of my time to implement a Tektronix
terminal emulator under X.  So I set to work learning
more C--I had only written a couple of wrappers to C I/O
routines so I could use them with my Fortran software--and
wrote a Tektronix emulator.  The only X documentation at
the time was the code itself.  While I was at it, I wrote
an improved Tektronix emulator for our Imagen laser printer
which used the full resolution of that 300 dpi printer instead
of the effective 100 dpi (i.e. jaggy) emultator distributed
with the printer.  The original xterm Tek emulator shared a
window with the VT100 emulator, much like on the VT240 terminals
which I had been using at MIT before I came to Harvard.  With
a VAX 750 running several VS100's, window creation was sloowww,
so sharing a window was the quickest way to do things, and all
of my software was written for that mode of operation, anyway.
While I wrote the emulator so that my software would work on
it, it was tested by the X group against a BBN graphics package,
the name of which slips my mind right now.
<p>
Anyway, 15 years later, I am still using xterm and some of the
same mapping software I wrote the emulator for.  And I am still
at the Smithsonian Astrophysical Observatory.
</blockquote>
<P>
This FAQ is oriented toward the version of xterm distributed with XFree86,
which is based on the X11R6.3 xterm, with the addition of ANSI color and
VT220 controls.

<H1><A NAME="what_platforms">What platforms does it run on?</A></H1>
<code>Xterm</code> runs in all of the implementations of X11.
I've built and run these since I started working on xterm:

<UL>
<LI>AIX 3.2.5 (cc)
<LI>Digital Unix 3.2, 4.0 (cc)
<LI>FreeBSD 2.2.6 to 5.1 (gcc 2.8)
<LI>HP-UX 9.05 (gcc 2.7.2)
<LI>IRIX 5.2, 6.2 (cc, gcc 2.7.2, gcc 2.8)
<LI>Linux 2.0.0 to 2.4.22 (gcc 2.7.2 to 3.3)
<LI>SCO OpenServer 5 (cc, gcc).
<LI>Solaris 2.4, 2.5, 2.5.1, 2.6, 7, 8 (cc, gcc 2.7.2)
<LI>SunOS 4.1.1, 4.1.3 (gcc 2.7.2)
</UL>
<P>
Most of these configurations have X11R5 libraries.  Only minor changes
are needed to make xterm work on those systems.  However, with X11R6
you can obtain better locale support, as well as new features such as the
active icon.

<H1><A NAME="latest_version">What is the latest version?</A></H1>
The most recent (and well supported) version of xterm is the XFree86 version.
I have a copy at
<P>
Ftp: <A HREF="ftp://invisible-island.net/xterm/xterm.tar.gz">ftp://invisible-island.net/xterm/xterm.tar.gz</A>

<H1><A NAME="other_versions">What versions are available?</A></H1>
There are several other versions of xterm, as well as similar programs.
These include
<UL>
<LI><A HREF="#bug_ansi_xterm">ansi_xterm</A>
<LI><A HREF="#bug_color_xterm">color_xterm</A>
<LI><A HREF="#bug_cxterm">cxterm</A> (Chinese)
<LI><A HREF="#bug_dtterm">dtterm</A>
<LI><A HREF="#bug_emu">emu</A> (from X Consortium)
<LI><A HREF="#bug_eterm">Eterm</A>
<LI><A HREF="#bug_gnometerm">GNOME Terminal</A>
<LI><A HREF="#bug_multignome">Multi GNOME Terminal (MGT)</A>
<LI><A HREF="#bug_hanterm">hanterm</A> (Korean)
<LI><A HREF="#bug_mterm">mterm</A>
<LI><A HREF="#bug_mxterm">mxterm</A>
<LI><A HREF="#bug_nxterm">nxterm</A>
<LI><A HREF="#bug_konsole">konsole</A>
<LI><A HREF="#bug_kterm">kterm</A> (Japanese)
<LI><A HREF="#bug_mlterm">mlterm</A> (Multi Lingual)
<LI><A HREF="#bug_rxvt">rxvt</A>
<LI><A HREF="#bug_xgterm">xgterm</A>
<LI><A HREF="#bug_xiterm">xiterm</A>
<LI><A HREF="#bug_xterm_r6">xterm</A> (from X Consortium)
</UL>
(I am aware of a few others, such as
<STRONG>xcterm</STRONG>, but have not seen
a working version of these).
<p>
There were for some time two versions of XFree86 xterm.  Starting with my
<a href="xterm.log.html#xterm_88">patch 88</a>,
there were the stable (beta) and unstable (alpha) versions, which currently
are XFree86 3.3.6 and XFree86 4.x, respectively.
I made only critical changes to the stable version since
patch 88;
ongoing development (including all non-critical fixes)
was focused on the "unstable".
<p>
XFree86 4.0 should have incorporated my
<a href="xterm.log.html#xterm_131">patch 131</a>,
but it was overlooked at the last moment
(though it was listed in the ChangeLog, the patch itself was not applied).
Unfortunately, the patch 130 version which was released
renders colors incorrectly on most platforms, in particular FreeBSD.
Ironically, the change in
<a href="xterm.log.html#xterm_129">patch 129</a>
which introduced this bug
was designed to work around a bug which I have seen only running with FreeBSD.
To compound the irony,
there was some resistance at the time
(2000/4/5) by that organization to incorporating the fix
because it might be confused with the 4.0 release version.

<H1><A NAME="how_do_i">How do I ...</A></H1>
Not really problems, but frequently asked questions (the point of this,
after all):
<UL>
<LI><A HREF="#how2_fsize">How do I change the font size?</A>
<LI><A HREF="#how2_print">How do I print the screen?</A>
<LI><A HREF="#how2_fkeys">How do I set up function keys?</A>
<LI><A HREF="#how2_title">How do I set the title?</A>
<LI><A HREF="#how2_blink">How do I make the cursor blink?</A>
</UL>

<H2><A NAME="how2_fsize">How do I change the font size?</A></H2>
This is in the manpage, in <em>MENUS</em>.
<p>
X Consortium xterm provides popup menus, by pressing the control key
together with the mouse button.
Control right mouse button pops up the <em>VT FONTS</em> menu,
from which you can select fonts that are specified in xterm's resources.
Usually these are in increasing order of size.
<p>
XFree86 xterm provides the menu, plus a feature adapted from rxvt: pressing
the shifted keypad plus or minus keys steps through the font menu selections,
in order of their size.

<H2><A NAME="how2_print">How do I print the screen?</A></H2>
That depends on why you want to print it.
<p>
If you want a trace of an interactive session, you should use the
<em>script</em> program.  It records every character sent to the
screen, recording them in a file <code>typescript</code>.
There are two drawbacks to this approach:
<ul>
<li>Every character is recorded.
Even cursor movement, if you run an editor.
<li>You must start a new shell to capture the <code>typescript</code> file.
</ul>
Well, what about logging?
Some versions of xterm support logging to a file.
In fact XFree86 xterm does.  Logging was dropped from X Consortium xterm
during X11R5 due to security concerns.  Those were addressed, but logging
was not reinstated
(in fact there is a related <a href="#bug_xterm_r6">bug</a> in xterm).
Some people prefer this, because it is convenient:
you can start and stop logging a popup menu entry.
However
<ul>
<li>Every character is recorded.
Even cursor movement, if you run an editor.
<li>Line drawing characters are translated to control characters,
i.e., codes 0-31
(this may be fixed sometime,
it is a problem inherited from X Consortium xterm).
</ul>
Both <em>script</em> and logging are useful for recording, but they
require interpretation to make sense of the trace.  You probably
would not send that trace to a printer (not twice, anyway).
<p>
If you want to print the contents of the screen, XFree86 xterm
implements, as part of the VT100 emulation, an "attached" printer.
<ul>
<li>The printer is really a pipe command, to which xterm writes.
<li>You can print the current line, page, or continuously with
the corresponding control sequences.  That takes an application
program which knows how to print the screen.
<li>If you do not have an application, xterm has a popup menu
entry to print the window.
</ul>
There are limitations and tradeoffs using the "attached" printer,
because it is an emulation:
<ul>
<li>The emulation is based on detailed documentation for a VT320.
This states that control sequences are sent in each line to
reset bold, underlining and other printable attributes, and
to set them as needed.
Your printer probably does not understand this sort of input.
Use the xterm resource <code>printAttributes</code> to get
more easily printed output.
<li>The printer may hang.
Not really, but it seems that way.
If you use the "attached" printer from an application designed
for the VT100 terminal, it is written with the assumption that
the printer is a dedicated piece of hardware,
printing onto a continuous form.
Use the <code>printerAutoClose</code> resource to change
xterm's behavior to close the printer pipe whenever the terminal
is told to switch the printer offline.
</ul>
If you use the popup menu to print the screen, this will close the
printer pipe unless it was already opened by the application running in xterm.

<H2><A NAME="how2_fkeys">How do I set up function keys?</A></H2>
With XFree86 xterm, this is relatively simple.  So I'll answer that first.
<P>
With X Consortium xterm, you have partial support for DEC VTxxx function keys.
Function keys F1 to F12 correspond to DEC's F1 to F12 (sort of).
Actually, DEC's VT220 terminals do not have codes for F1 through F5.
They are reserved for local functions.
And the VT220 (and up) terminals have 20 function keys.
So you cannot do anything with the F13 through F20 (i.e., DO, HELP and SELECT).
Finally, though xterm is reputed to be VT100-compatible, it has no support
for the VT100 keypad (PF1 to PF4, and the "," key).
<P>
XFree86 xterm changes the X Consortium codes for F1 to F4 to match the
VT100 PF1 to PF4, except when the emulation level is VT220 and up.
In this case, it generates the same F1 to F4 codes as X Consortium xterm.
Moreover, it adds a new resource <code>sunKeyboard</code>, which
tells the program whether it has only 12 function keys (i.e., a Sun or PC
keyboard).
If so (this is selectable from the popup menu), you can use the control key
with F1 to F12 to get F13 to F24, and use the "+" key on the keypad as an
alias for "," (comma).
<P>
The emulation level for XFree86 xterm is set via the resource
<code>decTerminalID</code>, e.g., to 220 for a VT220.
Once set, applications can set the emulation level up or down within that
limit.  DEC's terminals are configured in much the same way by a setup
option.
<P>
That is the simple way, using a couple of new resources.
The traditional way to get function keys involves translations.
I have seen a few postings on the newsgroups that do this.
Here is one from Bruce Momjian &lt;root@candle.pha.pa.us&gt;
for a VT220:
<PRE><code>
	xterm $XTERMFLAGS +rw +sb +ls $@ -tm 'erase ^? intr ^c' \
		-name vt220 -title vt220 -tn xterm-220 "$@" &amp;
</code></PRE>
<P>
with the corresponding resources:
<PRE><code>
	XTerm*VT100.translations: #override \n\
		&lt;Key&gt;Home: string(0x1b) string("[3~") \n \
		&lt;Key&gt;End: string(0x1b) string("[4~") \n
	vt220*VT100.translations: #override \n\
	~Shift	&lt;Key&gt;F1: string(0x1b) string("OP") \n \
	~Shift	&lt;Key&gt;F2: string(0x1b) string("OQ") \n \
	~Shift	&lt;Key&gt;F3: string(0x1b) string("OR") \n \
	~Shift	&lt;Key&gt;F4: string(0x1b) string("OS") \n \
	~Shift	&lt;Key&gt;F5: string(0x1b) string("[16~") \n \
	~Shift	&lt;Key&gt;F6: string(0x1b) string("[17~") \n \
	~Shift	&lt;Key&gt;F7: string(0x1b) string("[18~") \n \
	~Shift	&lt;Key&gt;F8: string(0x1b) string("[19~") \n \
	~Shift	&lt;Key&gt;F9: string(0x1b) string("[20~") \n \
	~Shift	&lt;Key&gt;F10: string(0x1b) string("[21~") \n \
	~Shift	&lt;Key&gt;F11: string(0x1b) string("[28~") \n \
	~Shift	&lt;Key&gt;F12: string(0x1b) string("[29~") \n \
	Shift	&lt;Key&gt;F1: string(0x1b) string("[23~") \n \
	Shift	&lt;Key&gt;F2: string(0x1b) string("[24~") \n \
	Shift	&lt;Key&gt;F3: string(0x1b) string("[25~") \n \
	Shift	&lt;Key&gt;F4: string(0x1b) string("[26~") \n \
	Shift	&lt;Key&gt;F5: string(0x1b) string("[K~") \n \
	Shift	&lt;Key&gt;F6: string(0x1b) string("[31~") \n \
	Shift	&lt;Key&gt;F7: string(0x1b) string("[31~") \n \
	Shift	&lt;Key&gt;F8: string(0x1b) string("[32~") \n \
	Shift	&lt;Key&gt;F9: string(0x1b) string("[33~") \n \
	Shift	&lt;Key&gt;F10: string(0x1b) string("[34~") \n \
	Shift	&lt;Key&gt;F11: string(0x1b) string("[28~") \n \
	Shift	&lt;Key&gt;F12: string(0x1b) string("[29~") \n \
		&lt;Key&gt;Print: string(0x1b) string("[32~") \n\
		&lt;Key&gt;Cancel: string(0x1b) string("[33~") \n\
		&lt;Key&gt;Pause: string(0x1b) string("[34~") \n\
		&lt;Key&gt;Insert: string(0x1b) string("[2~") \n\
		&lt;Key&gt;Delete: string(0x1b) string("[3~") \n\
		&lt;Key&gt;Home: string(0x1b) string("[1~") \n\
		&lt;Key&gt;End: string(0x1b) string("[4~") \n\
		&lt;Key&gt;Prior: string(0x1b) string("[5~") \n\
		&lt;Key&gt;Next: string(0x1b) string("[6~") \n\
		&lt;Key&gt;BackSpace: string(0x7f) \n\
		&lt;Key&gt;Num_Lock: string(0x1b) string("OP") \n\
		&lt;Key&gt;KP_Divide: string(0x1b) string("Ol") \n\
		&lt;Key&gt;KP_Multiply: string(0x1b) string("Om") \n\
		&lt;Key&gt;KP_Subtract: string(0x1b) string("OS") \n\
		&lt;Key&gt;KP_Add: string(0x1b) string("OM") \n\
		&lt;Key&gt;KP_Enter: string(0x1b) string("OM") \n\
		&lt;Key&gt;KP_Decimal: string(0x1b) string("On") \n\
		&lt;Key&gt;KP_0: string(0x1b) string("Op") \n\
		&lt;Key&gt;KP_1: string(0x1b) string("Oq") \n\
		&lt;Key&gt;KP_2: string(0x1b) string("Or") \n\
		&lt;Key&gt;KP_3: string(0x1b) string("Os") \n\
		&lt;Key&gt;KP_4: string(0x1b) string("Ot") \n\
		&lt;Key&gt;KP_5: string(0x1b) string("Ou") \n\
		&lt;Key&gt;KP_6: string(0x1b) string("Ov") \n\
		&lt;Key&gt;KP_7: string(0x1b) string("Ow") \n\
		&lt;Key&gt;KP_8: string(0x1b) string("Ox") \n\
		&lt;Key&gt;KP_9: string(0x1b) string("Oy") \n

	!	&lt;Key&gt;Up: string(0x1b) string("[A") \n\
	!	&lt;Key&gt;Down: string(0x1b) string("[B") \n\
	!	&lt;Key&gt;Right: string(0x1b) string("[C") \n\
	!	&lt;Key&gt;Left: string(0x1b) string("[D") \n\

	*visualBell:	true
	*saveLines:    1000
	*cursesemul:	true
	*scrollKey: true
	*scrollBar: true
</code></PRE>
Note that real VT220 terminals use shifted function keys to mean something
different: the user-programmable keys (i.e., DECUDK).  XFree86 xterm
supports this, but the translations do not (they're using shift to select
F13 to F20).
<P>
Here's another one, from
Robert Ess &lt;ress@spd.dsccc.com&gt;:
<PRE><code>
	#!/bin/sh

	#		vax
	# 09-17-96	Bob Ess      - initial creation
	# 09-26-96	Shig Katada  - Additional keybindings
	#
	#		Script file to incorporate keybindings and command line
	#		options for connecting to a VAX node

	# Usage statement
	Usage(){
		echo
		echo " Usage  : vax -options"
		echo
		echo " Options: -80   for 80 column terminal"
		echo "          -132  for 132 column terminal"
		echo "          -fg colorname"
		echo "          -bg colorname"
		echo "          -fn fontname"
		echo "          -fb bold fontname"
		echo "          -host [altair] [devel] [leonis] [castor]"
		echo ""
		echo " Example: \"vax -80 -fg white -bg black -fn 9x15 -fb 9x15b -host castor\""
		echo "          Starts a VAX session with an 80 column terminal"
		echo "          with a black background, white foreground, a normal"
		echo "          font of 9x15 and a bold font of 9x15b, and connects"
		echo "          to the node 'castor'"
		echo
		echo "          If you need additional help, please call Workstation"
		echo "          Services at x92396."
		echo
		exit 1
	}


	# Default to a black foreground with a white background.
	# Use the 9x15 and 9x15bold fonts. Connect to castor by default.
	#
	FG=black
	BG=white
	HOST=castor
	FONT=9x15
	BFONT=9x15bold
	COLS=80


	# Parse the command line arguments
	#
	while [ $# != 0 ];
	do
		case $1 in
			-80)	COLS=80
				FONT=spc12x24c
				BFONT=spc12x24b
				shift
				;;
			-132)	COLS=132
				FONT=9x15
				BFONT=9x15b
				shift
				;;
			-fg)	shift
				FG=$1
				shift;;
			-bg)	shift
				BG=$1
				shift;;
			-fn)	shift
				FONT=$1
				shift;;
			-fb)	shift
				BFONT=$1
				shift;;
			-host)	shift
				HOST=$1
				shift;;
			-help)	Usage;;
			*)	Usage;;
		esac
	done


	xterm  -title "VAX" -sb -sl 1200 -geo ${COLS}x24 -fg ${FG} -bg ${BG} \
		-cr red -fn ${FONT} -fb ${BFONT} -xrm \
		'XTerm*VT100.translations:     #override \n\
		&lt;Key&gt;Insert:            string(\001) \n\
		Shift &lt;Key&gt;Up:          scroll-back(1,lines) \n\
		Shift &lt;Key&gt;Down:        scroll-forw(1,lines) \n\
		Shift &lt;Key&gt;Right:       string(0x1b) string("f") \n\
		Shift &lt;Key&gt;Left:        string(0x1b) string("b") \n\
		Shift &lt;Key&gt;Delete:      string(0x1b) string(0x08) \n\
		Shift &lt;Key&gt;Tab:         string(0x1b) string("*") \n\
		&lt;Key&gt;0x1000FF0D:        scroll-back(1,page) \n\
		&lt;Key&gt;0x1000FF0E:        scroll-forw(1,page) \n\
		&lt;Key&gt;0x1000FF09:        string(\010) \n\
		&lt;Key&gt;0x1000FF0A:        string(\005) \n\
		&lt;Key&gt;BackSpace:         string(0xff) \n\
		&lt;Key&gt;Select:            select-start() \n\
		&lt;Key&gt;0x1000FF02:        select-end(PRIMARY,CUT_BUFFER0) \n\
		Meta &lt;Key&gt;0x1000FF02:   select-end(CLIPBOARD) \n\
		&lt;Key&gt;0x1000FF04:        insert-selection(PRIMARY,CUT_BUFFER0) \n\
		Meta &lt;Key&gt;0x1000FF04:   insert-selection(CLIPBOARD) \n\
		&lt;Key&gt;F1:                string(0x1b) string("OP") \n\
		&lt;Key&gt;F2:                string(0x1b) string("OQ") \n\
		&lt;Key&gt;F3:                string(0x1b) string("OR") \n\
		&lt;Key&gt;F4:                string(0x1b) string("OS") \n\
		&lt;Key&gt;F5:                string(0x1b) string("OA") \n\
		&lt;Key&gt;F11:               string(0x1b) string("[23~") \n\
		&lt;Key&gt;F12:               string(0x1b) string("[24~") \n\
		&lt;Key&gt;KP_0:              string(0x1b) string("Op") \n\
		&lt;Key&gt;KP_1:              string(0x1b) string("Oq") \n\
		&lt;Key&gt;KP_2:              string(0x1b) string("Or") \n\
		&lt;Key&gt;KP_3:              string(0x1b) string("Os") \n\
		&lt;Key&gt;KP_4:              string(0x1b) string("Ot") \n\
		&lt;Key&gt;KP_5:              string(0x1b) string("Ou") \n\
		&lt;Key&gt;KP_Divide:         string(0x1b) string("OP") \n\
		&lt;Key&gt;KP_Multiply:       string(0x1b) string("[29~") \n\
		&lt;Key&gt;KP_Enter:          string(0x1b) string("OM") \n\
		&lt;Key&gt;KP_Subtract:       string(0x1b) string("Om") \n\
		&lt;Key&gt;KP_Add:            string(0x1b) string("Ol") \n\
		&lt;Key&gt;KP_Decimal:        string(0x1b) string("On") \n\
		&lt;Btn1Down&gt;:             select-start() \n\
		&lt;Btn1Motion&gt;:           select-extend() \n\
		&lt;Btn1Up&gt;:               select-end(PRIMARY,CUT_BUFFER0) \n\
		Button1&lt;Btn2Down&gt;:      select-end(CLIPBOARD) \n\
		Button1&lt;Btn2Up&gt;:        ignore()' \
		-e telnet $HOST &amp;
</code></PRE>
Finally (for the moment) is a further modification of Robert Ess's script
by <a href="http://www-personal.une.edu.au/~oahlefel/">Erik Ahlefeldt</a>,
&lt;oahlefel@metz.une.edu.au&gt;.
From his readme file, for vmsterm:

<blockquote>
 This script is for people who wish to connect from a Linux or Unix computer
 to a VMS computer using telnet and get a good VT100 or VT220 emulation.
 The key mappings have been specifically designed to emulate the VT terminal
 auxiliary numeric keypad, so that you can use VMS EDT and TPU editors, as well
 as the many VMS applications use keys PF1 to PF4. The script should work with
 any recent version of Xterm using a standard extended IBM PC keyboard or
 a Sun keyboard.
<p>
 About the keymappings. First the auxiliary numeric keypad.
 My prime objective with these mappings was to produce a setup that
 I could use with the EDT and TPU editors which make extensive use of the
 numeric keypad. The top row of keys PC numeric keypad (Num Lock, Divide,
 Multiply, Subtract) are where you find PF1, PF2, PF3, PF4 on a VT keyboard,
 so I have mapped them to PF1 thru PF4. The PC numeric keypad Add key (+) takes
 up the space of two keys which are Minus and Comma on the VT keyboard - I have
 mapped it to Comma (Delete Character in the EDT editor). I have then used the
 PC Pause key to map to VT key Minus (Delete Word in the EDT editor). The
 remaining keys on the auxiliary numeric keypad are the same for PC and VT.
<p>
 The six keys between the main and numeric keypads on the PC (Insert, Home,
 Page Up, Delete End, Page Down) are usually mapped to the VT keys by either
 position or by (approximate) function. As I rarely use these keys I have
 mapped them by function as follows: PC key Insert to VT Insert Here,
 PC Home to VT Find, PC Page Up to VT Prev, PC Delete to VT Remove, PC
 End to VT Select, PC Page Down to VT Next.
<dl>
<dt>Function keys.
<dd>There are 12 function keys on the PC keyboard and 20 on the
 VT keyboard, so I map PC F1 thru F12 to VT F1 thru F12 (except for F1 thru F5
 as noted below) and PC Shift F1 thru Shift F10 to VT F11 thru F20.
<p>
 The VT keys F1 thru F5 are local hardware function keys so there is nothing
 to emulate, however some PC to VT emulations in the past have mapped PF1 thru
 PF4 here, so I have done that too, even though they are already mapped on the
 auxiliary numeric keypad.
<dt>Xterm functionality.
<dd>You lose some xterm functions when you remap the
 keyboard, however this script implements a scroll back buffer of 1000 lines
 which you scroll through using Shift and Up (a.k.a. Up Arrow or Cursor Up key)
 or Shift and Down.
</dl>
</blockquote>
a summary of the keyboard mapping:
<pre>
		PC Key     maps to   VT Key.
		------               ------
		F1                   PF1
		F2                   PF2
		F3                   PF3
		F4                   PF4
		F5                   unused
		F6                   F6
		F7                   F7
		F8                   F8
		F9                   F9
		F10                  F10
		F11                  F11
		F12                  F12
		Shift F1             F11
		Shift F2             F12
		Shift F3             F13
		Shift F4             F14
		Shift F5             F15 (Help)
		Shift F6             F16 (Do)
		Shift F7             F17
		Shift F8             F18
		Shift F9             F19
		Shift F10            F20
		Shift F11            F11
		Shift F12            F12
		Print                Help (F15)
		Cancel               Do   (F16)
		Pause                Keypad Minus

		Insert               Insert Here
		Delete               Remove
		Home                 Find
		End                  Select
		Prior                Prev
		Next                 Next
		BackSpace            BackSpace (sends DEL - ascii 127)

		Num_Lock             PF1
		KP_Divide            PF2
		KP_Multiply          PF3
		KP_Subtract          PF4
		KP_Add               Keypad Comma
		KP_Enter             Enter
		KP_Decimal           Period
		KP_0                 Keypad 0
		KP_1                 Keypad 1
		KP_2                 Keypad 2
		KP_3                 Keypad 3
		KP_4                 Keypad 4
		KP_5                 Keypad 5
		KP_6                 Keypad 6
		KP_7                 Keypad 7
		KP_8                 Keypad 8
		KP_9                 Keypad 9
		Up                   Up
		Shift Up             Scroll Back
		Down                 Down
		Shift Down           Scroll Forward
		Right                Right
		Left                 Left
</pre>
and the script:
<pre><code>
	#!/bin/sh
	#               vmsterm
	#               from an original script by Bob Ess
	#               key translations by Erik Ahlefeldt
	#
	#               Script file using Xterm and telnet to connect to a VMS host
	#               and give a decent vt220 emulation.
	#
	# Usage statement
	Usage(){
		echo
		echo " Usage  : vmsterm -options"
		echo
		echo " Options: -80   for 80 column terminal"
		echo "          -132  for 132 column terminal"
		echo "          -bg colorname"
		echo "          -fg colorname"
		echo "          -fn fontname"
		echo "          -fb bold fontname"
		echo "          -host [crusher.saltmine.com] [earth] [192.168.7.7]"
		echo ""
		echo " Example: \"vmsterm -80 -fg white -bg black -fn 9x15 -fb 9x15b -host earth\""
		echo "          Starts a VMS session with an 80 column terminal"
		echo "          with a black background, white foreground, a normal"
		echo "          font of 9x15 and a bold font of 9x15b, and connects"
		echo "          to the node 'earth'"
		echo ""
		echo " Example: \"vmsterm -host earth\""
		echo "          Starts a VMS session with default terminal settings "
		echo ""
		echo " Example: \"vmsterm -help\""
		echo "          Displays vmsterm options "
		echo
		exit 1
	}

	# Default to a black foreground with a white background.
	# Use the 9x15 and 9x15bold fonts. Connect to 192.168.3.3 by default.
	#
	FG=black
	BG=white
	HOST=192.168.3.3
	FONT=9x15
	BFONT=9x15bold
	COLS=80

	# Parse the command line arguments
	#
	while [ $# != 0 ];
	do
		case $1 in
			-80)    COLS=80
				FONT=spc12x24c
				BFONT=spc12x24b
				shift
				;;
			-132)   COLS=132
				FONT=9x15
				BFONT=9x15b
				shift
				;;
			-fg)    shift
				FG=$1
				shift;;
			-bg)    shift
				BG=$1
				shift;;
			-fn)    shift
				FONT=$1
				shift;;
			-fb)    shift
				BFONT=$1
				shift;;
			-host)  shift
				HOST=$1
				shift;;
			-help)  Usage;;
			*)      Usage;;
		esac
	done

	xterm	-title "VMSTERM" -sb -sl 1000 -geo ${COLS}x24 -fg ${FG} -bg ${BG} \
		-cr blue -fn ${FONT} -fb ${BFONT} -xrm \
		'XTerm*VT100.translations: #override \n \
		~Shift	&lt;Key&gt;F1:	string(0x1b)	string("OP") \n \
		~Shift	&lt;Key&gt;F2:	string(0x1b)	string("OQ") \n \
		~Shift	&lt;Key&gt;F3:	string(0x1b)	string("OR") \n \
		~Shift	&lt;Key&gt;F4:	string(0x1b)	string("OS") \n \
		~Shift	&lt;Key&gt;F5:	string("Break") \n \
		~Shift	&lt;Key&gt;F6:	string(0x1b)	string("[17~") \n \
		~Shift	&lt;Key&gt;F7:	string(0x1b)	string("[18~") \n \
		~Shift	&lt;Key&gt;F8:	string(0x1b)	string("[19~") \n \
		~Shift	&lt;Key&gt;F9:	string(0x1b)	string("[20~") \n \
		~Shift	&lt;Key&gt;F10:	string(0x1b)	string("[21~") \n \
		~Shift	&lt;Key&gt;F11:	string(0x1b)	string("[23~") \n \
		~Shift	&lt;Key&gt;F12:	string(0x1b)	string("[24~") \n \
		Shift   &lt;Key&gt;F1:	string(0x1b)	string("[23~") \n \
		Shift   &lt;Key&gt;F2:	string(0x1b)	string("[24~") \n \
		Shift   &lt;Key&gt;F3:	string(0x1b)	string("[25~") \n \
		Shift   &lt;Key&gt;F4:	string(0x1b)	string("[26~") \n \
		Shift   &lt;Key&gt;F5:	string(0x1b)	string("[28~") \n \
		Shift   &lt;Key&gt;F6:	string(0x1b)	string("[29~") \n \
		Shift   &lt;Key&gt;F7:	string(0x1b)	string("[31~") \n \
		Shift   &lt;Key&gt;F8:	string(0x1b)	string("[32~") \n \
		Shift   &lt;Key&gt;F9:	string(0x1b)	string("[33~") \n \
		Shift   &lt;Key&gt;F10:	string(0x1b)	string("[34~") \n \
		Shift   &lt;Key&gt;F11:	string(0x1b)	string("[28~") \n \
		Shift   &lt;Key&gt;F12:	string(0x1b)	string("[29~") \n \
			&lt;Key&gt;Print:	string(0x1b)	string("[28~") \n \
			&lt;Key&gt;Cancel:	string(0x1b)	string("[29~") \n \
			&lt;Key&gt;Pause:	string(0x1b)	string("Om") \n \
			&lt;Key&gt;Insert:	string(0x1b)	string("[2~") \n \
			&lt;Key&gt;Delete:	string(0x1b)	string("[3~") \n \
			&lt;Key&gt;Home:	string(0x1b)	string("[1~") \n \
			&lt;Key&gt;End:		string(0x1b)	string("[4~") \n \
			&lt;Key&gt;Prior:	string(0x1b)	string("[5~") \n \
			&lt;Key&gt;Next:	string(0x1b)	string("[6~") \n \
			&lt;Key&gt;BackSpace:	string(0x7f)	\n \
			&lt;Key&gt;Num_Lock:	string(0x1b)	string("OP") \n \
			&lt;Key&gt;KP_Divide:	string(0x1b)	string("OQ") \n \
			&lt;Key&gt;KP_Multiply: string(0x1b)	string("OR") \n \
			&lt;Key&gt;KP_Subtract: string(0x1b)	string("OS") \n \
			&lt;Key&gt;KP_Add:	string(0x1b)	string("Ol") \n \
			&lt;Key&gt;KP_Enter:	string(0x1b)	string("OM") \n \
			&lt;Key&gt;KP_Decimal: string(0x1b)	string("On") \n \
			&lt;Key&gt;KP_0:	string(0x1b)	string("Op") \n \
			&lt;Key&gt;KP_1:	string(0x1b)	string("Oq") \n \
			&lt;Key&gt;KP_2:	string(0x1b)	string("Or") \n \
			&lt;Key&gt;KP_3:	string(0x1b)	string("Os") \n \
			&lt;Key&gt;KP_4:	string(0x1b)	string("Ot") \n \
			&lt;Key&gt;KP_5:	string(0x1b)	string("Ou") \n \
			&lt;Key&gt;KP_6:	string(0x1b)	string("Ov") \n \
			&lt;Key&gt;KP_7:	string(0x1b)	string("Ow") \n \
			&lt;Key&gt;KP_8:	string(0x1b)	string("Ox") \n \
			&lt;Key&gt;KP_9:	string(0x1b)	string("Oy") \n \
		~Shift	&lt;Key&gt;Up:		string(0x1b)	string("[A") \n \
		Shift	&lt;Key&gt;Up:		scroll-back(1,lines) \n \
		~Shift	&lt;Key&gt;Down:	string(0x1b)	string("[B") \n \
		Shift	&lt;Key&gt;Down:	scroll-forw(1,lines) \n \
			&lt;Key&gt;Right:	string(0x1b)	string("[C") \n \
			&lt;Key&gt;Left:	string(0x1b)	string("[D")' \
		-e telnet $HOST
</code></pre>

<H2><A NAME="how2_title">How do I set the title?</A></H2>
The control sequences are documented in
<a href="ftp://invisible-island.net/xterm/ctlseqs.txt.gz">ctlseqs.ms</a>;
a copy is contained in the <A HREF="#latest_version">xterm.tar.gz</A> file.
<P>
The usual context for this question is setting the title according to
the current working directory.
People post answers to this periodically on the newsgroups.
Here is one that I have seen,
from Roy Wright &lt;nobody@roystoy.dseg.ti.com&gt;.
In your /etc/profile after:
<PRE><code>
	if [ "$SHELL" = "/bin/pdksh" -o "$SHELL" = "/bin/ksh" ]; then
		PS1="! $ "
	elif [ "$SHELL" = "/bin/zsh" ]; then
		PS1="%m:%~%# "
	elif [ "$SHELL" = "/bin/ash" ]; then
		PS1="$ "
	else
		PS1='\u@\h:\w\$ '
	fi
</code></PRE>
<P>
add:
<PRE><code>
	if [ "$TERM" = "xterm" ]; then
		PS1="\033]2;\u@\h:\w\007bash$ "
	fi
</code></PRE>
<P>
The terminator "\007" is a problem area.  Xterm historically uses this
character, though it is non-ANSI.  The "correct" character should be
a "\233" string terminator, or "\033\\", which is the 7-bit equivalent.
XFree86 xterm recognizes either (the "\007" or string terminator);
waiting for the first of these.
<P>
You may have resource or environment problems that prevent you from
setting the title at all.  Newer xterms (starting somewhere in X11R5)
use the $LANG variable.  If your locale is incorrectly installed, you
will be unable to set the xterm's title.
As noted by Mikhail Teterin &lt;mi@rtfm.ziplink.net&gt;:
Make sure that the locale (LANG and/or LOCALE environment variable)
is known to X Window System.
Check ${X11ROOT}/lib/X11/locale.* for it.
If it is not listed in either one of the files, find
the nearest match and add an alias to it.
Restart X if you have made changes.
<P>
On a related note, some people want to know how to read the title
from an xterm.
This works for XFree86 xterm and dtterm, but not for other variations:
<PRE><code>
	#!/bin/ksh
	# Echo the current X term title bar to standard output.
	# Written by Icarus Sparry &lt;icarus@bath.ac.uk&gt; 11 Apr 1997
	#
	exec &lt;/dev/tty
	old=$(stty -g)
	stty raw -echo min 0  time ${1-10}
	print "\033[21t\c" &gt; /dev/tty
	IFS='' read -r a
	stty $old
	b=${a#???}
	print -R "${b%??}"
</code></PRE>
But it is possible to avoid escape sequences altogether (from
Hemant Shah &lt;shah@typhoon.xnet.com&gt;):
<PRE><code>
	$ xprop -id $WINDOWID | grep WM_NAME
	WM_NAME(STRING) = "this is my title"
	current_title=$(xprop -id $WINDOWID | grep WM_NAME | cut -d= -f2)
</code></PRE>
Here's another source of information:
<a href="http://www.giccs.georgetown.edu/~ric/howto/Xterm-Title/">Xterm-Title HowTo</a>

<H2><A NAME="how2_blink">How do I make the cursor blink?</A></H2>
Standard xterm does not implement a blinking cursor.
Some of the variations do:
dtterm,
GNOME Terminal,
and XFree86 xterm
(from mid 1999, <a href="xterm.log.html#xterm_107">patch 107</a>).

<H1><A NAME="frequent_problems">Frequent problems</A></H1>
<UL>
<li>Starting xterm, or not
<ul>
<LI><A HREF="#no_ptys">Xterm does not run (no available pty's)</A>
<LI><A HREF="#no_ncurses">I need libncurses.so.3.0</A>
<LI><A HREF="#no_termcap">I need /etc/termcap</A>
<LI><A HREF="#no_libpath">Why does $LD_LIBRARY_PATH get reset?</A>
<LI><A HREF="#no_ls_and_e">Why do the -e and -ls options not work together?</A>
<LI><A HREF="#setup_resize">Why is my screen size not set?</A>
<LI><A HREF="#tiny_menus">Why are the menus tiny?</A>
</ul>
<LI>Font problems
<ul>
<LI><A HREF="#no_altchar">My terminal doesn't show box characters</A>
<LI><A HREF="#scaled_font">The bold font is ugly</A>
<LI><A HREF="#little_dot">I see little dots on the screen</A>
<LI><A HREF="#no_russian">My terminal doesn't display Cyrillic characters</A>
</ul>
<li>Keyboard problems
<ul>
<LI><A HREF="#xterm_8bits">Why can't I input 8-bit characters?</A>
<LI><A HREF="#xterm_erase">Why doesn't my delete key work?</A>
<LI><A HREF="#xterm_erased">Why did my delete key stop working?</A>
<LI><A HREF="#xterm_xmodmap">Well, how can I set my delete key?</A>
<LI><A HREF="#xterm_keypad">Why doesn't my keypad work?</A>
<LI><A HREF="#xterm_pageup">Why can't I use the pageup/pagedown keys?</A>
<LI><A HREF="#xterm_pc_style">Why can't I use the home/end keys?</A>
<LI><A HREF="#xterm_arrows">Why can't I use the cursor keys in (whatever) shell?</A>
</ul>
<li>Colors and other graphic rendition
<ul>
<LI><A HREF="#no_color">My terminal doesn't recognize color</A>
<LI><A HREF="#xterm_terminfo">What $TERM should I use?</A>
<LI><A HREF="#xterm_hilite">Reverse video is not reset</A>
</ul>
<li>Odd behavior
<ul>
<LI><A HREF="#xterm_paste">Why can't I cut/paste in xterm?</A>
<LI><A HREF="#xterm_resize">FVWM does weird things when I try to resize xterm</A>
<LI><A HREF="#xterm_tite">Why doesn't the screen clear when running vi?</A>
<LI><A HREF="#xterm_vite">Why is the cursor misplaced after running vi?</A>
</ul>
<LI><A HREF="#warning_msg">What is this warning message?</A>
</UL>

<H2><A NAME="no_altchar">My terminal doesn't show box characters</A></H2>
Xterm displays the 7-bit ASCII and VT100 graphic characters (including
box corners) using specially arranged fixed-pitch fonts.  The first
32 glyph positions (which would correspond to nonprinting control
characters) are used to hold the VT100 graphic characters.  Some
fonts that otherwise look fine (such as courier) do not have glyphs
defined for these positions.  So they display as blanks.
Use <em>xfd</em> to display the font.
<p>
XFree86 xterm can form its own line-drawing characters
(see <a href="xterm.log.html#xterm_90">patch 90</a>, for example).
It does not draw all of the graphic characters, only those that
may be done with straight lines.  But those are the most used,
making most of the fixed-pitch fonts useful for xterm.
<p>
You may also have a problem with the terminfo description.
As distributed, the X11R6 terminfo for xterm does not have the
<em>acsc</em> string defined, so most implementations of curses
do not try to use the alternate character set.
<p>
Finally, some people confuse the VT100 graphic characters with the VT220
support for DEC technical character set.
These are distinct (7-bit) character sets.
Xterm currently does not support this.

<H2><A NAME="scaled_font">The bold font is ugly</A></H2>
Xterm lets you directly specify one bold font, which is assumed to
correspond to the default font.
Older versions of xterm make a fake bold font for the other choices
via the fonts menu by drawing the characters offset by one pixel.
I modified xterm to ask the font server for a bold font that corresponds
to each font (other than the default one).
Usually that works well.
However, sometimes the font server gives a poor match.
Xterm checks for differences in the alignment and size,
but the font server may give incorrect information about the font size.
The scaled bitmap font feature gives poor results for the smaller fonts.
In your X server configuration file, that can be fixed by disabling
the feature, e.g.,
by appending ":unscaled" to the path:
<pre><code>
	FontPath	"/usr/lib/X11/fonts/100dpi/:unscaled"
	FontPath	"/usr/lib/X11/fonts/75dpi/:unscaled"
	FontPath	"/usr/lib/X11/fonts/misc/:unscaled"
</code></pre>

<H2><A NAME="little_dot">I see little dots on the screen</A></H2>
Well, I do.
Perhaps you do not.
It depends on the fonts you choose, and how you use them.
<p>
Standard xterm has a "normal" font for which a bold font can be chosen,
and several alternative fonts, useful for changing the font size.
The alternative fonts do not have corresponding bold fonts.
Xterm simulates bold fonts in this case by overstriking the character
one pixel offset.  That can make an bold character extend into the
area that another character occupies. When erasing a bold character from
the screen, xterm does not erase the extra pixel.

This is corrected in XFree86 xterm,
subject to the available fonts
(from late 1998, <a href="xterm.log.html#xterm_85">patch 85</a>).
For each font, it asks the font server for a corresponding bold font.
Your font server may not have the bold font (or it may incorrectly
report that it does).  But it usually works.

<H2><A NAME="no_russian">My terminal doesn't display Cyrillic characters</A></H2>
Cyrillic encodings typically use characters in the range 128-159.
For a VT220 (or any terminal that follows ISO 6429), those are treated
as control characters.
Still, some people want to use KOI8-R, etc.
I modified xterm in
<a href="xterm.log.html#xterm_175">patch 175</a>
to add an option (<code>-k8</code>)
and corresponding resource settings to allow them to customize their
environment.
Here is a
<a href="ftp://invisible-island.net/xterm/koi8-term">sample script</a> and
<a href="ftp://invisible-island.net/xterm/KOI8Term">resource file</a> which
I use for testing this configuration.

<H2><A NAME="no_color">My terminal doesn't recognize color</A></H2>
First, ensure that you have set up xterm to render color.
The XFree86 xterm renders color only if you have set resources
to do this; the default behavior is monochrome to maintain compatibility
with older applications.
The manual page describes these resources.
I set them in my <A HREF="#my_xdefaults">.Xdefaults</A> file.
<p>
Even if you set the resources properly, there may be another application
running which prevents xterm from allocating the colors you have specified.
But you should see a <a href="#alloc_color">warning message</a> for this.
<P>
Check the terminal description, to see if it is installed properly,
e.g., for
<A HREF="../ncurses/ncurses.faq.html#no_color">ncurses</A>, which uses terminfo.
<P>
Finally, some applications (that do not interface properly with terminfo
or termcap) may need the environment variable
<a href="../ncurses/ncurses.faq.html#no_colorterm">$COLORTERM</a> to be set.

<H2><A NAME="setup_resize">Why is my screen size not set?</A></H2>
Well, it may be set, but not correctly. You may notice these symptoms:
<ul>
<li>When editing with vi, you cannot see the beginning of the file, or
<li>Running
<pre><code>
	stty -a
</code></pre>
shows the rows and/or columns values as 0, or some other value (such as 65)
which has nothing to do with the actual window size.
</ul>
Xterm knows how big the screen is (of course), and tries to tell your
applications (e.g., by invoking ioctl's and sending SIGWINCH).  But sometimes
it cannot:
<ul>
<li>Xterm itself may have been built incorrectly
(the #ifdef's that make the logic work are inactive).
<li>You may be running xterm via a remote connection which refuses to pass
that information.  This can happen even on "modern" networks where the connection
crosses domain boundaries.
<li>You may be running su'd to another account.
SIGWINCH is just another signal; signals do not propagate for security reasons.
</ul>
Most full-screen applications such as vi are designed to use the ioctl
calls that return the screen size.  When they fail, the applications
use the size defined in the terminal's terminfo or termcap description.
<p>
You may be able to use the <em>resize</em> program to issue the ioctl's
that will notify your application of the actual screen size. This does not
always work for the reasons just mentioned.
Newer versions of stty let you specify the screen size, though it will not
be updated if you resize the xterm window:
<pre><code>
	stty rows 24 columns 80
</code></pre>
Most full-screen applications also
check if the $LINES and $COLUMNS variables are set, using those values to
override the terminal description:
<pre><code>
	setenv LINES 24
	setenv COLUMNS 80
</code></pre>
Why 65 lines?  The standard xterm terminfo description specifies 65 lines,
perhaps because someone liked it that way.  Real VT100's are 24 lines.
I once used (and wrote applications for) a Bitgraph terminal, which
emulated VT100, but displayed 65 lines.

<H2><A NAME="xterm_pageup">Why can't I use the pageup/pagedown keys?</A></H2>
Some vendors, e.g,. Sun, have added key translations which make the
pageup and pagedown keys talk to the xterm's scrollbar instead of your
application.
They did the same thing for the home and end keys, thereby obscuring
a bug in <A HREF="#bug_xterm_r6">xterm</A>.
<p>
You can override this by specifying your own translations in your resource
file.
Use the translations in
<pre><code>
	/usr/lib/X11/app-defaults/XTerm
</code></pre>
as a guide.
The relevant section of the app-default file looks like
<pre><code>
	*VT100.translations:    #override \
		@Num_Lock&lt;Key&gt;KP_0: string(0)\n\
		@Num_Lock&lt;Key&gt;KP_1: string(1)\n\
		@Num_Lock&lt;Key&gt;KP_2: string(2)\n\
		@Num_Lock&lt;Key&gt;KP_3: string(3)\n\
		@Num_Lock&lt;Key&gt;KP_4: string(4)\n\
		@Num_Lock&lt;Key&gt;KP_5: string(5)\n\
		@Num_Lock&lt;Key&gt;KP_6: string(6)\n\
		@Num_Lock&lt;Key&gt;KP_7: string(7)\n\
		@Num_Lock&lt;Key&gt;KP_8: string(8)\n\
		@Num_Lock&lt;Key&gt;KP_9: string(9)\n\
		@Num_Lock&lt;Key&gt;KP_Add: string(+)\n\
		@Num_Lock&lt;Key&gt;KP_Decimal: string(.)\n\
		@Num_Lock&lt;Key&gt;KP_Divide: string(/)\n\
		@Num_Lock&lt;Key&gt;KP_Enter: string(\015)\n\
		@Num_Lock&lt;Key&gt;KP_Equal: string(=)\n\
		@Num_Lock&lt;Key&gt;KP_Multiply: string(*)\n\
		@Num_Lock&lt;Key&gt;KP_Subtract: string(-)\n\
		&lt;Key&gt;Prior:scroll-back(1,page)\n\
		&lt;Key&gt;Next:scroll-forw(1,page)\n\
		&lt;Key&gt;F16: start-extend() select-end(PRIMARY, CUT_BUFFER0, CLIPBOARD) \n\
		&lt;Key&gt;F18: insert-selection(PRIMARY, CLIPBOARD) \n\
		&lt;Key&gt;F27: scroll-back(100,page) \n\
		&lt;Key&gt;R13: scroll-forw(100,page) \n\
		&lt;Key&gt;Home: scroll-back(100,page) \n\
		&lt;Key&gt;End: scroll-forw(100,page) \n
</code></pre>
For example, a more-specific pattern for the resource name lets you override:
<pre><code>
	XTerm.VT100.translations:       #override \n\
		~Shift&lt;Key&gt;Home:  string(\033[1~)\n\
		~Shift&lt;Key&gt;End:   string(\033[4~)\n\
		~Shift&lt;Key&gt;Prior: string(\033[5~)\n\
		~Shift&lt;Key&gt;Next:  string(\033[6~)\n\
		Shift&lt;Key&gt;Prior:  scroll-back(1,page) \n\
		Shift&lt;Key&gt;Next:   scroll-forw(1,page) \n\
		Shift&lt;Key&gt;Home:   scroll-back(100,page) \n\
		Shift&lt;Key&gt;End:    scroll-forw(100,page) \n
</code></pre>
makes the home/end and pageup/pagedown keys usable by your editor,
while leaving their shifted equivalents available for the scrollbar.

<H2><A NAME="xterm_pc_style">Why can't I use the home/end keys?</A></H2>
This is a long story,
unless you are referring to X Consortium <A HREF="#bug_xterm_r6">xterm</A>.
That program is simply broken in this respect.
<p>
At the beginning, when the home/end keys were fixed for XFree86 xterm
(in early 1996), there was some discussion regarding what the escape
sequences should be for those keys (for the 6-key editing keypad).
Those were chosen as "PC-style" codes (like SCO "ansi"), i.e.,
<pre>
	ESC [ H
	ESC [ F
</pre>
for normal mode, and
<pre>
	ESC O H
	ESC O F
</pre>
for cursor application mode.
<p>
That style of coding fit easily into the existing logic of xterm.
It was not my change, and (because xterm should be based upon standards),
I did question this, and asked the opinion of the person who was at that
time developing rxvt.
He had chosen a layout based on DEC's VT220 terminals,
though the key labels on the typical PC keyboard did not
<A HREF="#xterm_keypad">match</A>.
At that point, neither of us knew enough to make a good case for this.
<p>
Somewhat later I could see that xterm had a number of undocumented
extensions to support the VT220-style (pre-ISO 2022) character sets.
I decided to complete the functionality by making xterm a VT220 emulator.
This would require that it provide the same escape sequences for the
editing and numeric keypads.
I could not simply change the escape sequences from "PC-style" to "VT220-style",
since a number of users "knew" that the keypad "ought to" send home, end,
cursor keys, etc., because they had labels indicating that use.
To retain compatibility (but allow easy reconfiguration to make a VT220
emulator), I added popup-menu items to switch between the modes.
With minor refinements, this was the approach for about two years,
culminating with the <a HREF="xterm.log.html#xterm_88">"stable" patch #88</a>,
which is essentially the version distributed with XFree86 3.3.x.
<dl>
<dt><em>NOTE</em>:
<dd>the terminfo distributed with xterm patch #88 is incorrect:
the escape sequences given for home/end keys are
the VT220-style, rather than the default PC-style.
Too accustomed to switching modes on the fly, I overlooked a line in
my .Xdefaults file:
<pre><code>
		*sunKeyboard: true
</code></pre>
Downstream packagers (when they noticed this)
accommodated the bug by modifying the VT100 translations
resource which is not a good technical solution since it interferes with
the users' ability to modify that resource.
See <A HREF="#xterm_xmodmap">this</A> for more discussion.
</dl>

But xterm continues to evolve past the stable patch #88.
The keyboard support was still unsatisfactory for two reasons:
<ul>
  <li>some users wanted to be able to use applications that detected whether
    the control key was pressed (e.g., control/F1).
  <li>the compromises made for <code>xkb</code> with X11R6 interfered with
    xterm's use of the NumLock key for the numeric keypad.
</ul>
The former could be addressed by expanding the escape sequences sent by the
PC-style function keys,
while the latter was a VT100/VT220 design issue.
I decided to redesign function-key support to separate the two styles of
function keys better, but leaving the choice still controlled by the
<code>sunKeyboard</code> resource.
Partway through that, I was asked to do similar cleanup and redesign of
the backspace and delete key handling, e.g.,
the <A HREF="#xterm_erased">ptyInitialErase</A> resource.
Because it is a redesign, I chose to not make the keyboard differences
between the old and new xterms completely compatible.
If you were to run both on the same system, one or the other would have
some problems with the editing keypad or the backspace/delete keys
which would be addressed by the popup-menu selections.
<p>
For example, at this time (2001/9/4):
<ul>
<li>Debian stable is xterm-88c, which should be identical to the XFree86 3.3.6
version, but is not (there are some label differences in the resource-file, but
nothing interesting relative to home/end keys).
And of course, Debian changes
the terminfo <code>kbs</code> from <code>^H</code> to <code>^?</code>.
As noted, the terminfo I wrote for XFree86 3.3.x has an error.
Setting 
<pre><code>
		*sunKeyboard: true
</code></pre>
in the app-defaults file fixes the problem with xterm-88, which was that I
documented in the terminfo the behavior <em>with</em> that resource set.
Similarly, setting
<pre><code>
		*backarrowKey: false
</code></pre>
is one way to address Debian's change to <code>kbs</code>.

<li>Debian unstable is xterm-149.
Other than omitting the color resources from
the app-defaults file, I see that it sets
	*backarrowKeyIsErase: true
which would not affect the home/end keys.
(The color resources are redundant, so that is not a problem either).
</ul>
<a href="XTerm-debian-88c">Here is a resource file</a>
which I tested with xterm-88c, xterm-149 and xterm-158,
using $TERM set to xterm-debian.

<H2><A NAME="xterm_arrows">Why can't I use the cursor keys in (whatever) shell?</A></H2>
VTxxx (VT100 and up) terminals may send different escape sequences for
the cursor (arrow) keys depending on how they are set up.
The choices are referred to as the normal and application modes.
Initially, the terminal is in normal mode.
<p>
VTxxx terminals are usually set up so that
full-screen applications will use
the cursor application mode strings.
This is good for full-screen
applications, including legacy applications which may have hard-coded
behavior, but bad for interactive shells (e.g., ksh, tcsh, bash)
which use arrow keys to scroll through a history of command strings.
<p>
To see the difference between normal/application modes, consider this example:
<ul>
      <li>In normal (non-application) mode, the terminal transmits a down-arrow
        as \E[C, which happens to echo as a down-arrow.

      <li>In application mode the terminal transmits \EOC, which echoes as C.
        That is because the \EO is the SS3 control, which says to use the
        character from the G3 character set for the next cell.
</ul>
Since termcaps and terminfo descriptions are written for
full-screen applications, shells and similar programs often
rely on built-in tables of escape sequences which they use instead.
Defining keys in terms of the termcap/terminfo entry (e.g., by capturing
the string sent by tputs) is apt to confuse the shell.
<p>
Depending on the terminal type,
the keypad(s) on the keyboard may switch modes along with the
cursor keys, or have their own independent modes.
The control sequences for these are independent of the ones used for
cursor-addressing, but are grouped together, e.g., as the
terminfo <code>smkx</code> and <code>rmkx</code> capabilities.
Terminfo entries are written assuming that the application has initialized
the terminal using the <code>smkx</code> string before it is able to
match the codes given for the cursor or keypad keys.

<H2><A NAME="xterm_paste">Why can't I cut/paste in xterm?</A></H2>
When an application sets xterm to any of its mouse tracking modes, it reserves
the unshifted mouse button clicks for the application's use.
Unless you have modified the treatment of the shifted mouse button events
(e.g., with your window manager), you can always do cut/paste by pressing
the shift key while clicking with the mouse.

<H2><A NAME="no_ncurses">I need libncurses.so.3.0</A></H2>
During initialization, xterm checks to see if the value of $TERM is
legal, i.e., is defined via the termcap interface.
Some people have linked xterm against ncurses, which provides a similar
interface, since they do not want to package termcap on their system.
<P>
The libncurses.so.3.0 corresponds to ncurses 1.9.8a; while there have
been interface changes to ncurses past this point (the current version of
<A HREF="../ncurses/ncurses.faq.html#latest_version">ncurses</A>),
the termcap interface should still be compatible.
So (for xterm) it doesn't matter much which version of ncurses you have
installed.  However, other applications may not work properly.
Some people have advised just linking libncurses.so.2.0 to libncurses.so.3.0,
but that won't work well at all (one person simply linked libncurses.so.3.0
to the libtermcap.so, which may work...).
A better solution would be to install the later version of ncurses,
with a link (if you must) from the newer version to the older library.
<P>
Since there is little agreement on the set of shared libraries that
are assumed to be present on the user's system, XFree86 distributes
xterm statically linked against termcap because that is simplest,
and because you lose functionality (the $TERMCAP variable) when linked
against terminfo libraries such as ncurses.

<H2><A NAME="no_libpath">Why does $LD_LIBRARY_PATH get reset?</A></H2>
If xterm is running setuid (which is needed on some systems which have
no wrappers for opening pty's and updating utmp), newer systems automatically
set or reset environment variables which are considered security problems.
These include <code>$PATH</code> and <code>$LD_LIBRARY_PATH</code>, since
they affect the choice of which programs are run if not specified via a
full pathname.
<p>
This means, for example, that if you attempt to run
<pre><code>
	xterm -e foo
</code></pre>
where <code>foo</code> is a program that uses shared libraries in
<code>/usr/local/lib</code>, then the command will fail, because
<code>/usr/local/lib</code> is not considered part of <code>root</code>'s
environment.
<p>
Modern Unix systems (such as recent Solaris and HPUX versions) do not require
you to run xterm setuid.  Some will result in odd malfunctions if you do this.

<H2><A NAME="no_ls_and_e">Why do the -e and -ls options not work together?</A></H2>
Xterm has two useful options for controlling the shell that is run:
<dl>
<dt>-e
<dd>tells xterm to execute a command using the remaining parameters after
this option.
<dt>-ls
<dd>tells xterm to invoke a login shell, making it read your <code>.login</code>
file, for instance.
</dl>
The two are not compatible.
If you specify both, xterm uses <code>-e</code>, and if that fails for
whatever reason will fall through to the <code>-ls</code> option. 
It cannot (in general) combine the two, since some shells permit this
(e.g., bash), and others do not (e.g., tcsh).

<H2><A NAME="no_termcap">I need /etc/termcap</A></H2>
If you have a termcap version of xterm on a system with no termcap libraries,
you may also be missing /etc/termcap.
<P>
A workaround is to copy /usr/X11R6/lib/X11/etc/xterm.termcap to
/etc/termcap.
<P>
This is fixed another way starting with XFree86 3.3.1.
If xterm cannot find the terminal description, it will accept that,
though it will print a warning.  If xterm does not find the termcap
entry, it will not set the $TERMCAP variable.

<H2><A NAME="no_ptys">Xterm does not run (no available pty's)</A></H2>
Your copy of xterm may not have enough permissions to use existing pty's:
<ul>
<li>you may have to make xterm run setuid to root
(though newer systems have wrappers that make this unnecessary).
<li>the pty's permissions may be restrictive (that is ok, but you have
to make xterm agree with it).
Usually this is done by making the group ownership of the pty's "tty",
and requiring that xterm run setgid to "tty".
This is done rather than make xterm run setuid to root, since that
presents problems with security.
<li>newer systems (with Unix98 pty's) have a single entry under /dev
which has to have the right permissions.
For example:
<pre><code>
	# ls -l /dev/ptmx
	crw-rw----    1 root     tty        5,   2 Aug 21 20:19 /dev/ptmx
</code></pre>
</ul>
<p>
Perhaps your system does not have enough pty's, or (problems
reported with newer Linux kernels supporting Unix98 pty's,
beginning with RedHat 6.0) the major device
numbers of the pty's may have changed during a kernel upgrade.
(This is described in <code>/usr/src/linux/Documentation</code>).
<p>
See also the MAKEDEV script, which usually exists under /dev.

<H2><A NAME="xterm_hilite">Reverse video is not reset</A></H2>
When running <em>less</em> or other programs that do highlighting,
you see the highlighting not turned off properly.
<P>
This may be due to incompatible terminal descriptions for xterm.
With XFree86 3.2, I modified the terminal description for XFree86
xterm to use the VT220 (aka ISO 6429) controls that allow an application
to turn off highlighting (or bold, underline) without modifying the
other attributes.  The X Consortium xterm does not recognize these
controls.
<P>
If, for example, you are running an older xterm and rlogin to a system
where the newer xterm has been installed, you will have this problem,
because both programs default to $TERM set to xterm.
The solution for mixed systems is to install the newer terminal description as
as a different name (e.g., <code>xterm-color</code>)
and set the <code>termName</code>
resource accordingly in the app-defaults file for the system which has the
newer xterm.
<p>
However - see <a href="#xterm_terminfo">below</a>.

<H2><A NAME="xterm_terminfo">What $TERM should I use?</A></H2>
<p>
The <code>xterm-color</code> value for $TERM
is a bad choice for XFree86 xterm because it is
commonly used for a terminfo entry which happens to not support <code>bce</code>.
Complicating matters, FreeBSD (after dithering for a few years on the matter)
introduced a bastardized version which implies the opposite sense of <code>bce</code>,
(because it uses SGR 39 and 49), but does not set it.
The most recent version
provides the <code>xterm-xfree86</code> entry which is distributed with
XFree86 xterm (which corresponds to the one distributed with ncurses).
<p>
The term "<code>bce</code>" stands for "back color erase".
Terminals such as XFree86 xterm
and rxvt implement back color erase, others such as dtterm do not.
(Roughly half of the emulators that I know about implement bce).
When an application clears the screen, a terminal that implements back
color erase will retain the last-set background color.  A terminal
that does not implement back color erase will reset the background color
to the default or initial colors.  Applications that paint most of the
screen in a single color are more efficient on terminals that support
back color erase.
<p>
Curses libraries that support color know about <code>bce</code> and do the
right thing - provided that you tell them what the terminal does.
That is the whole point of setting $TERM.
The "xterm-color" description distributed with ncurses does not list
<code>bce</code>, because it was applied originally to a terminal type
which does
not implement back color erase.
It will "work" for XFree86 xterm,
though less efficient.  Some other applications such as the slang library
have hardcoded support for terminals that implement back color erase.
Given the "xterm-color" description, those will be efficient - and
fortuitously work.  However, slang (through version 1.4.0) does not
work properly for the terminals that xterm-color was designed for.
See this <a href="../lynx/lynx-ncurses.html">page</a> for an example
of (n)curses and slang running on dtterm.
That bug in slang is reported to be fixed for succeeding versions, though
your application may require changes to use this fix.
(The demo which comes with slang to illustrate the use of <code>bce</code>
does not work properly, for instance).
<p>
The <code>xterm-color</code> value for $TERM
is also (for the same reason) a bad choice for rxvt, but
"works" due to the large number of hard-coded applications that override
this.
<p>
Some people recommend using <code>xtermc</code>.
That is installed on Solaris.
However, it does not match any xterm in current use.
(Apparently it was written for an obsolete version on Unixware).
The colors work, true, but the mouse will not, nor will the function keys.

<H2><A NAME="xterm_resize">FVWM does weird things when I try to resize xterm</A></H2>
I have an old (3.1.2G) bug report for xterm which may be related to the
second (3.9s) problem:
<ul>
<li>Steven Lang &lt;tiger@ecis.com&gt; reports a problem with extra resize
events for xterm.
<P>
When I change font size often I will get the double-refresh, and when that
happens the text program gets 2 resize events..  Running a quick test, I
got this: Going to a bigger font, it got a 53x20 resize, then a 80x24
resize.  Going to a smaller font, it got a 120x27 resize, then a 80x24
resize.
<P>
Earlier I made a mention of changing font size in rxvt (And xterm does it
to) causing 2 resize events.  Well I just happened to do it in fvwm
(Instead of fvwm 95) and found it seems to be a 'feature' of fvwm95, not
XFree86 as I'd initially assumed.
<li>Stephen Marley &lt;stephen@memex.com&gt; reports a problem with the active
icon (from X11R6.3 xterm):
<p>
Using the XFree86 xterm-53 with the active icon feature on, I get
some problems resizing where the xterm window shrinks as small
as possible and won't stay at whatever size you set it thereafter.
<p>
Comment out the PixmapPath and IconPath from your .fvwmrc file to
disable the fvwm icons and restart the WM.
Start an xterm.
Iconify xterm and maximize it again.
Use resize button or corners to resize the xterm.
<p>
The xterm now shrinks to a tiny size and attempts to resize it
result in it shrinking again.
<p>
I've tried this with fvwm 1.23 and fvwm 2.0.46 with the same results.
Olvm, olvwm and twm all behave correctly so it may be a fvwm problem.
</ul>
I have not observed the first, but have reproduced the second.

<H2><A NAME="xterm_tite">Why doesn't the screen clear when running vi?</A></H2>
Under SunOS 4.x, the termcap description for xterm embeds in the
<code>ti</code> and <code>te</code> capabilities a command to switch to
xterm's alternate screen (e.g., while running <code>vi</code>), and return
to the normal screen on exit.
This has the effect of clearing the screen.
Under Solaris 2.x, the terminfo description does not use the alternate
screen (it is a matter of preference after all), so that the text from
vi remains on the screen after exit.
There are corresponding terminfo symbols for
<code>ti</code> and <code>te</code>:
<code>smcup</code> and <code>rmcup</code>, respectively.
<P>
This is configurable.
<p>
For example (from Bjorn Helgaas &lt;helgaas@dhc.net&gt;)
this procedure adds these capabilities to the "xterm"
terminfo definition on HP-UX 10.20:
<pre><code>
	cp /usr/lib/terminfo/x/xterm /usr/lib/terminfo/x/xterm.orig
	untic xterm &gt; /tmp/xterm.src
	echo " smcup=\E7\E[?47h, rmcup=\E[2J\E[?47l\E8," &gt;&gt; /tmp/xterm.src
	tic /tmp/xterm.src
</code></pre>
In this example, the terminfo strings are a series of operations:
<dl>
<dt><code>smcup</code>
<dd><code>\E7</code> saves the cursor's position
<dd><code>\E[?47h</code> switches to the alternate screen
<dt><code>rmcup</code>
<dd><code>\E[2J</code> clears the screen (assumed to be the alternate screen)
<dd><code>\E[?47l</code> switches back to the normal screen
<dd><code>\E8</code> restores the cursor's position.
</dl>
<p>
However, xterms that are linked with termcap are more flexible in this area
than those linked with terminfo libraries.
The xterm program supports a resource <code>titeInhibit</code> which
manipulates the $TERMCAP variable to accomplish this.  It sets the $TERMCAP
variable for the client with the <code>ti</code> and <code>te</code> capabilities
suppressed.
Systems that use terminfo cannot do this.  If you are running terminfo
with the alternate screen controls in the terminal description, then
you can suppress the switching to the alternate screen by the
<code>titeInhibit</code>, but not the associated cursor save/restore
and clear-screen operations.
<P>
XFree86 3.9s xterm implements a different set of controls
(private setmodes 1047, 1048 and 1049) which address
this (in addition to the older set of controls, for compatibility).
The new set of controls implements the entire <code>ti</code> sequence
(save cursor, switch to alternate screen, clear screen)
and <code>te</code>
(switch to normal screen, restore cursor)
as two control sequences that can be disabled by <code>titeInhibit</code>.
<p>
The 1049 code is a refinement of 1047 and 1048, clearing the alternate
screen before switching to it rather than after switching back to the
normal screen.
This allows you (with a popup menu entry designed to exploit this behavior) to
switch the display back to the alternate screen to select text from it,
to paste into the normal screen.
You can also set or clear the <code>titeInhibit</code> resource using another
popup menu entry (<code>Enable Alternate Screen Switching</code>).

<H2><A NAME="xterm_vite">Why is the cursor misplaced after running vi?</A></H2>
Vi and other full-screen applications use the termcap <code>ti/te</code> (terminfo
<code>smcup/rmcup</code>) strings to initiate and end cursor addressing mode.
As mentioned in the discussion of <A HREF="#xterm_tite">titeInhibit</A>,
full-screen applications can expect the initialization string to save
the cursor's position, and the end-string to restore it.
<P>
A few applications (reportedly IRIX 5.x and 6.x <code>vi</code>
incorrectly move the cursor before initializing cursor-addressing.
This will cause the end-string to restore the cursor to its position
when it was saved by the initialization string (typically at the
upper left corner of the screen).
<p>
The usual reason is due to the cursor save/restore controls in
the <code>ti/te</code> strings.  If your application runs a subprocess
which in turn runs another full-screen application (or when reinitializing
the screen after the shell process), it will save the
cursor position again, so the position which is restored when finally
exiting your program is the last one saved, not the first.
XFree86 xterm
(from late 1998, <a href="xterm.log.html#xterm_90">patch 90</a>)
changes the behavior of the cursor save/restore
operations so they apply only to the current screen.
That makes it less likely to misplace your cursor.

<H2><A NAME="xterm_erase">Why doesn't my delete key work?</A></H2>
This seems to be a problem with the older XFree86 release (3.1.2).
I have picked up pieces of the story (xterm and the keyboard work as
designed under XFree86 3.2 and up).
<p>
The underlying problem is that we've accumulated three things that are
being equated as "Delete":
<pre>
	ASCII backspace (code 8)
	ASCII delete (code 127)
	VT220 "remove" aka "delete" (ESC [ 3 ~)
</pre>
<P>
You are probably talking about the <STRONG>backarrow</STRONG> key
(on my keyboard, at the upper right of the QWERTY block),
or the key labeled <STRONG>delete</STRONG> which is on the 6-key "editing keypad".
Since xterm is emulating a VT100/VT220,
the backarrow key should generate a 127 (often displayed as <code>^?</code>).
You would use a control/H to obtain a backspace on a real VT220.
<P>
Tastes differ on Unix, people expect the backarrow key to generate a backspace
(or not).  As I understand it, at one point, XFree86 picked up the sense of the
erase character during initialization, so that xterm would in effect use the
same erase character as the console.  The current scheme (X11R6) uses keyboard
mapping tables that are independent of the environment.
<P>
XFree86 xterm provides a resource toggle <em>backarrowKey</em>
(and an escape sequence from VT320)
that changes this key between the two styles (backspace or delete).
<p>
With XFree86 xterm
<a href="xterm.log.html#xterm_95">patch 95</a>
(also in the stable version as "88c"),
you may have an xterm which can
automatically initialize the backarrow key to backspace or delete
depending on the pseudo terminal's sense, or based on the termcap
setting of <em>kbs</em> (backspace key).
This feature is controlled by the resource setting <em>ptyInitialErase</em>.

<H2><A NAME="xterm_erased">Why did my delete key stop working?</A></H2>
Well, something changed.
You have to determine what did.
<p>
This may be because an upgrade introduced different X resource settings,
or because you are using the newer xterm with the
<em>ptyInitialErase</em> resource (or perhaps both).
Use
<pre><code>
	appres XTerm
</code></pre>
to see the X resources that you are using, in particular the
<code>translation</code> (or
<code>Translation</code>)
resource for the vt100 widget.
<p>
One unexpected scenario came out of hiding when I was implementing the
<em>ptyInitialErase</em> resource.  When xterm is (by default) built
to support this, it sets the pty's erase character to match the
termcap entry.  Xterm also sets the $TERMCAP environment variable to match.
So everything is consistent, and everything defined.
The <code>stty erase</code> character is either backspace (^H) or delete (^?).
<p>
The problem arises because there are two things called "delete",
which were not well-defined: ASCII delete (127) and the PC-style
adaptation of VT220 <kbd>remove</kbd> assigned to the key Delete.
<p>
However, the <em>screen</em> program prefers to make the termcap
delete (<code>kD</code>) an &lt;escape&gt;[3~, which corresponds to the VT220
<kbd>remove</kbd> key.
If $TERMCAP is set when starting <em>screen</em>, it will translate stty's
erase character into the &lt;escape&gt;[3~, making most curses and
termcap applications work.
But stty still has the original erase character.
So low-level applications which check stty will not work.
I found that unsetting $TERMCAP before running would work, but this
was not a good solution.
Someone pointed out
(see <a href="xterm.log.html#xterm_129">patch 129</a>),
that the problem really was because termcap <code>kD</code> should delete
the character at the current position.  So it cannot be the same
as <code>stty erase</code>.
<p>
As a matter of fact, <code>stty erase</code> has to be a single character,
so &lt;escape&gt;[3~ would not work anyway.

<H2><A NAME="xterm_xmodmap">Well, how can I set my delete key?</A></H2>
When people first started asking this question in 1995-1996,
it appeared in the context of making Netscape work.
Netscape's use of the delete key running in X did not match user's expectations
when compared to that other platform.
They were commonly advised to use <em>xmodmap</em>, e.g.,
<pre><code>
	keysym BackSpace = Delete
</code></pre>
or
<pre><code>
	keycode 22 = 0xff08
</code></pre>
Either way is a bad technical solution - it works for some people
but not others (on my keyboard at work, keycode 22 is the numeric
keypad '9').
<p>
Alternatively, you can set resources.
This works reasonably well for environments where you have
different versions of xterm, e.g.,
<pre><code>
	XTerm*VT100.translations: #override \n\
		&lt;Key&gt;Delete: string(0x7f)
</code></pre>
I do not do that either, because it is not flexible.
Not all programs use the same sense of
<code>stty erase</code>;
some use termcap or terminfo,
and some are hardcoded.
So I prefer to be able to switch the xterm's keyboard at runtime.
You cannot do that with resources.
(Or not really - xterm has a <code>keymap()</code> action which could
support this if you provided a rather complex resource settings, but
the X library support for that is broken in X11R6).
Instead, I have added to XFree86 a set of resources (and popup menu entries)
to allow simple switching between the different styles of keyboard,
in particular for the backspace/delete issues.
See the manual page for
       <code>backarrowKey</code>
       <code>backarrowKeyIsErase</code> and
       <code>deleteIsDEL</code>
as well as
       <code>sunKeyboard</code>.

<H2><A NAME="xterm_keypad">Why doesn't my keypad work?</A></H2>
A few people have commented that the keypad does not work properly.
Aside from bugs (I have fixed a few), the most common problem seems
to be misconception.
<p>
Here's a picture of the VT100 numeric keypad:
<pre>
	+-----+-----+-----+-----+
	| PF1 | PF2 | PF3 | PF4 |
	+-----+-----+-----+-----+
	|  7  |  8  |  9  |  -  |
	+-----+-----+-----+-----+
	|  4  |  5  |  6  |  ,  |
	+-----+-----+-----+-----+
	|  1  |  2  |  3  |     |
	+-----+-----+-----+ ENT +
	|     0     |  .  |     |
	+-----+-----+-----+-----+
</pre>
and the similar Sun and PC keypads:
<pre>
	+-----+-----+-----+-----+
	| NUM |  /  |  *  |  -  |
	+-----+-----+-----+-----+
	|  7  |  8  |  9  |     |
	+-----+-----+-----+  +  +
	|  4  |  5  |  6  |     |
	+-----+-----+-----+-----+
	|  1  |  2  |  3  |     |
	+-----+-----+-----+ ENT +
	|     0     |  .  |     |
	+-----+-----+-----+-----+
</pre>
Working in X11, the NUM (NumLock) key has better uses than an alias
for PF1 (and is sometimes reserved).  I use the F1 through F4 on the keyboard
to implement PF1 through PF4, alias the keypad "+" to "," and use the existing
"-" key.
<p>
VT220 emulation uses the VT100 numeric keypad as well as a 6-key editing
keypad.
Here's a picture of the VT220 numeric keypad:
<pre>
	+--------+--------+--------+
	| Find   | Insert | Remove |
	+--------+--------+--------+
	| Select | Prev   | Next   |
	+--------+--------+--------+
</pre>
and the similar Sun and PC keypads:
<pre>
	+--------+--------+--------+
	| Insert | Home   | PageUp |
	+--------+--------+--------+
	| Delete | End    | PageDn |
	+--------+--------+--------+
</pre>
<p>
I chose to use keys that are mnemonic rather than in the "same" positions,
though some emulators (e.g., Tera Term) use the same positions:
<pre>
	+--------+--------+--------+
	| Insert | Find   | Prev   |
	+--------+--------+--------+
	| Remove | Select | Next   |
	+--------+--------+--------+
</pre>
<p>
I test the keyboard (for VT52/VT100/VT220) using
<A HREF="../vttest/vttest.html">vttest</A>.
If you find (or think that you have found) a problem with the keyboard
handling of xterm, please test it with vttest first.
<p>
Other arrangements of the keyboard are possible of course.
If you prefer to use the top row of the numeric keypad as PF1 through PF4,
you should do this using xterm's X resources.

<H2><A NAME="xterm_8bits">Why can't I input 8-bit characters?</A></H2>
You must have the <code>eightBitInput</code> resource set to do this.

<H2><A NAME="my_xdefaults">My .Xdefaults for XTERM</A></H2>
<PRE><code>
	XTerm*internalBorder:  10
	XTerm*highlightSelection:  true
	XTerm*VT100*colorBDMode:  on
	XTerm*VT100*colorBD:  blue
	XTerm*VT100*colorULMode:  on
	XTerm*VT100*colorUL:  magenta
	XTerm.VT100.eightBitInput:  true
	XTerm.VT100.eightBitOutput:  true
	XTerm*scrollBar:  true
	XTerm.VT100.titeInhibit:  true

	XTerm.VT100*colorMode:  on
	XTerm.VT100*dynamicColors:  on

	! Uncomment this to use color for underline attribute
	XTerm.VT100*colorULMode:  on
	XTerm.VT100*underLine:  off

	! Uncomment this to use color for the bold attribute
	XTerm.VT100*colorBDMode: on

	XTerm.VT100*color0: black
	XTerm.VT100*color1: red3
	XTerm.VT100*color2: green3
	XTerm.VT100*color3: yellow3
	XTerm.VT100*color4: blue3
	XTerm.VT100*color5: magenta3
	XTerm.VT100*color6: cyan3
	XTerm.VT100*color7: gray90
	XTerm.VT100*color8: gray30
	XTerm.VT100*color9: red
	XTerm.VT100*color10: green
	XTerm.VT100*color11: yellow
	XTerm.VT100*color12: blue
	XTerm.VT100*color13: magenta
	XTerm.VT100*color14: cyan
	XTerm.VT100*color15: white
	XTerm.VT100*colorUL: yellow
	XTerm.VT100*colorBD: white

	XTerm.VT100*cursorColor: lime green
</code>
</PRE>
XFree86 xterm comes with two copies of the resource file,
one with color only (<code>XTerm-col.ad</code>,
which is installed as <code>XTerm-color</code>),
and the regular one (<code>XTerm.ad</code>,
installed as <code>XTerm</code>).
To use the <code>XTerm-color </code>file in conjunction
with a separate <code>XTerm</code> app-defaults
file which does not contain color,
add the following line to your <code>.Xdefaults</code> file:
<PRE><code>
	*customization: -color
</code></PRE>

<H2><A NAME="tiny_menus">Why are the menus tiny?</A></H2>
Everything seems to work, except that the
xterm menus (VT options, fonts, etc.) do not display
properly; the menus pop up, but only with a tiny display
area in which none of the options are visible (and only
part of the menu title is visible).
<P>
You have specified the geometry for xterm too high in the hierarchy, and that
24x80 (or whatever the -geometry parameter happens to be) is applying to the
menus in pixels.
This resource makes the geometry apply to the menus as well as the VT100 widget:
<PRE><code>
	XTerm*geometry: 80x24
</code></PRE>
while this applies only to the VT100 widget
(which is probably what you intended):
<PRE><code>
	XTerm.VT100*geometry: 80x24
</code></PRE>
or better yet (to allow for the toolbar option, which uses a level of
widget hierarchy):
<PRE><code>
	XTerm*VT100*geometry: 80x24
</code></PRE>

<H2><A NAME="warning_msg">What is this warning message?</A></H2>
<DL>
<DT>xterm: Error 11, errno 22: permission denied
<DD>Actually, any message like this denotes a failure which requires
studying the xterm source to determine the exact problem.
<p>
You have either found a bug in xterm, or there is something wrong
with your computer's configuration, e.g., not enough pty's,
incorrect permissions, etc.
<p>
The first number is an internal code (defined in error.h in xterm's source),
and the second is the system error number (defined in /usr/include/sys/errno.h).
The system error number is easier to lookup, but the internal error code
tells you where to look in the source.
<DT>input method doesn't support my preedit type
<DD>Ignore this if you do not know what <em>input method</em> is.
Input methods are used to enter composite characters (e.g., umlauts,
other types of punctuated characters, East Asian characters, etc).
Your computer's libraries support this, but are missing configuration
tables, and xterm is warning you.
<p>
If the message bothers you (e.g., if you aren't starting xterm from
a window manager menu), you can suppress it by setting a resource:
<pre><code>
		XTerm*openIm:false
</code></pre>

<dt>Warning: Actions not found: ignore, "xxx"
<dd>The action "xxx" (for example "scroll-back") is specified in a resource
file whose translations match widgets that do not support them.
For example, this
<pre><code>
		XTerm*translations:     #override\n\
			&lt;Leave&gt;, ~Ctrl ~Meta &lt;Btn2Up&gt;: ignore()\n\
			~Shift &lt;Key&gt;KP_8: scroll-back(1,line)\n\
			~Shift &lt;Key&gt;KP_2: scroll-forw(1,line)\n\
			Shift &lt;Key&gt;KP_8: scroll-back(1,halfpage)\n\
			Shift &lt;Key&gt;KP_2: scroll-forw(1,halfpage)
</code></pre>
will produce warnings such as
<pre><code>
		Warning: Actions not found: ignore, scroll-back, scroll-forw
		Warning: Actions not found: ignore, scroll-back, scroll-forw
		Warning: Actions not found: ignore, scroll-back, scroll-forw
</code></pre>
This is a correct form, assigning the actions to the "VT100" widget.
<pre><code>
		XTerm*VT100.translations:     #override\n\
			&lt;Leave&gt;, ~Ctrl ~Meta &lt;Btn2Up&gt;: ignore()\n\
			~Shift &lt;Key&gt;KP_8: scroll-back(1,line)\n\
			~Shift &lt;Key&gt;KP_2: scroll-forw(1,line)\n\
			Shift &lt;Key&gt;KP_8: scroll-back(1,halfpage)\n\
			Shift &lt;Key&gt;KP_2: scroll-forw(1,halfpage)
</code></pre>

<dt><a name="alloc_color">Warning: Cannot allocate colormap entry for "xxx"</a>
<dd>This comes from the X library.
XFree86 xterm uses the default color map.
What this means is that if your X server has insufficient space to
store color information for more than one color map, other applications
which could use other color maps may conflict with xterm.
In practice, that is 256 unique colors on the screen at a time -- not enough
for a fancy background or an application such as Netscape.
<p>
During resource initialization, xterm attempts to allocate an entry from
the color map for each color which it might use.
If there are not enough free slots in the color map, you will see a
"Cannot allocate" message for each color that xterm failed to allocate.
Those colors will be rendered in the foreground color,
making full-screen color applications
such as <a href="../dialog/dialog.html">dialog</a> unreadable.
<p>
This problem is alleviated with
<a href="xterm.log.html#xterm_129">patch 129</a>,
which modified xterm to delay the most color allocation until
the colors are first needed.  If a color is never needed
(xterm allocates 20 colors in this manner),
that reduces the number of slots in the color map that are needed.
Even with this improvement, xterm must still allocate 4 colors during
initialization to determine how to display the cursor.
If none of those colors can be allocated, XFree86 xterm reverts to monochrome.
</DL>

<H2><A NAME="known_bugs">Known Bugs in XTERM</A></H2><P>
These are the known bugs (or limitations) in the XFree86 xterm.
They are also present in the other versions based on the X Consortium
sources (color_xterm, ansi_xterm, kterm).
<P>
Note that of the emulators that support color, most do not support
<code>bce</code> (back color erase).
The bce capability is also called the
"new color model", though it has been implemented in the IBM PC for
quite a while.
Technically, not implementing <code>bce</code>
(or allowing the choice between it and its complement) is not a bug,
since few hardware terminals (with good reason) implemented this feature.
<UL>
<LI>cut/paste does not select tabs; instead spaces are selected.
This is because the selection works from the array of displayed
characters, on which tab/space conversion has already been performed.
<LI>does not implement the autorepeat feature of VTxxx terminals.
</UL>

<H3><A NAME="bug_xterm_r6">X11R6.3 XTERM</A></H3>
The X Consortium version of xterm (and versions based on it) has
additional bugs not in XFree86 xterm:
<UL>
<LI>the program must be run with fixed (nonproportional) fonts.
<LI>the home and end keys do not generate usable escape sequences, due to
an indexing error.
(Note that it is possible to work around this using the VT100 translations
resource, but usually this is not done).
<LI>the Main Options menu is improperly constructed, due to incorrect
indices after removing the logging toggle.
This makes the list of signals off by one.
<LI>very large screens (e.g., by using nil2 for a font) cause core dumps
because the program uses a fixed array (200 lines) for adjusting pointers.
<LI>certain types of key translations cause a core dump because the program
does not check the event class before attempting to use events.
</UL>
(These bugs are also present in the X11R5 version).
<p>
Update 2004/04/08:
<br>
Complicating this discussion is the recently-released "X.Org" xterm.
That is the XFree86 xterm from XFree86 CVS
with all visible "xfree86" strings changed to "X.Org" or "xorg",
depending on the use.
For example the "xterm-xfree86" terminfo entry becomes "xterm-xorg".
The change history for the related CVS for X.Org shows this.
Similarly, the release notes for X11R6.7 include my notes for XFree86 4.4.
It is of course too soon to see the overall impact of this,
so I'll update this FAQ as I find it necessary.

<H3><A NAME="bug_color_xterm">COLOR_XTERM</A>
<A HREF="ftp://www.x.org/contrib/applications/color_xterm-beta1.tar.gz">download</A></H3>
This is based on the X Consortium X11R5 source, with the same bugs.
<UL>
<LI>implements non-bce color model
<LI>moving the cursor is reported to leave trails of incorrect color
<LI>clearing the screen resets colors (arguably this is a limitation).
</UL>
Not exactly a bug, but it does not build on Linux with X11R6.3

<H3><A NAME="bug_ansi_xterm">ANSI_XTERM</A>
<A HREF="ftp://www.x.org/contrib/applications/xterm-R6-sb_right-ansi-3d.tar.gz">download</A></H3>
This is based on the X Consortium source, with the same bugs.
<UL>
<LI>implements non-bce color model
<LI>fails
<A HREF="../vttest/vttest.html">vttest</A>
by not rendering reverse-video screen
</UL>

<H3><A NAME="bug_cxterm">CXTERM</A>
<A HREF="ftp://ftp.cuhk.hk/pub/chinese/ifcss/software/x-win/cxterm/">download</A></H3>
CXterm stands for "Chinese Xterm".
This is based on the X Consortium source.

<H3><A NAME="bug_dtterm">DTTERM</A></H3>
This is distributed with CDE.
It implements more of the DEC VT220 than the X Consortium xterm,
and also adds controls to manipulate the window and icon.
<UL>
<LI>implements non-bce color model
<LI>fails
<A HREF="../vttest/vttest.html">vttest</A>
by clearing its background to solid white rather
than preserving its sense in response to ED.
<LI>under some circumstances, scrolling margins are not recognized.
For instance, running
<A HREF="../vile/vile.html">vile</A>
which uses scrolling margins, we see text overwriting the status line.
</UL>

<H3><A NAME="bug_emu">EMU 1.3</A>
<A HREF="ftp://www.x.org/contrib/applications/emu-1.31.tar.gz">download</A></H3>
This is not based on the X Consortium source.
The authors state that it implements VT220 emulation.
It is in need of maintenance, since it builds with some problems to produce
an executable that (on Linux and SunOS) does not handle the carriage return
and newline translations properly.
So I am unable to run
<A HREF="../vttest/vttest.html">vttest</A>
on this emulator.

<H3><A NAME="bug_eterm">ETERM</A>
<A HREF="http://www.eterm.org/">link</A></H3>
Eterm was based on rxvt, though the appearance differs.
The terminal emulation capabilities appear similar, though
I am not able to run the full suite of tests in
<A HREF="../vttest/vttest.html">vttest</A>
with this emulator (the core dump noted for rxvt, as well as hanging while
awaiting response from one or more control sequences).
Oddly, it appears that neither Eterm nor rxvt implement CPR
(cursor position report).
Finally, it reserves F1 (function-key) for a popup menu.
This applies to versions of <EM>Eterm</EM> through 0.9.

<H3><A NAME="bug_gnometerm">GNOME TERMINAL</A>
<A HREF="http://www.gnome.org/">link</A></H3>
GNOME Terminal is developed separately from both xterm and rxvt,
and is based on the zvt (zterm) widget.
Like
<a href="#bug_kvt">kvt</a>),
it appears to have been developed imitating other terminal emulators
(Linux console and xterm) rather than strictly emulating a VT102.
The documentation is fragmentary (with a comment suggesting that the
author does not know where to find relevant information), and the
program fares badly with
<A HREF="../vttest/vttest.html">vttest</A>.
Beginning with late 1999, reports indicate that it
does not properly parse ANSI control
sequences:  the vim editor is using XFree86 xterm's vt220-style
"Send Device Attributes" (Secondary DA) control sequence to obtain the
terminal emulator's version.
That is, it sends
<pre><code>
	\E[&gt;c
</code></pre>
expecting a response such as
<pre><code>
	\E[&gt;0;138;0c
</code></pre>
for vt100.
The bug report indicates that the "c" sent by vim is echoed rather than
interpreted by the emulator.
<p>
But it suffices for vi.
<p>
Even the most recent GNOME Terminal (version 1.4.0.4, late 2001)
does not implement a complete vt102: it is missing several features
which can be demonstrated in
<A HREF="../vttest/vttest.html">vttest</A>).
Most of the bugs in the Device Attributes
responses remain, but it works a little better with vim.
However, there are problems with the alternate screen that show up with vim.
Again, these can be demonstrated with vttest (menu 11.6.3 in the 20011130 snapshot).

<H3><A NAME="bug_multignome">MULTI GNOME TERMINAL (MGT)</A>
<A HREF="http://multignometerm.sourceforge.net/">link</A></H3>
Of particular note, MGT 1.4.0 announcement claims that it works properly
for all of <A HREF="../vttest/vttest.html">vttest</A>)'s tests.
On the positive side, it does do VT52 emulation, but (reading the
source code did not help) it apparently does not really do VT220
from vttest's perspective.

<H3><A NAME="bug_hanterm">HANTERM</A>
<A HREF="http://www.bg.debian.org/Packages/frozen/x11/hanterm.html">download</A></H3>
HanTerm stands for "Hangul term" (Korean).
This is based on the XFree86 source.

<H3><A NAME="bug_konsole">KONSOLE</A>
<a href="http://www.kde.org/">link</a></H3>
More than just a rewrite of <a href="#bug_kvt">kvt</a> into C++.
But there are several incompatibilities between konsole 1.0.2 (late 2001)
and xterm:
<ul>
  <li>none of the selections of keyboard mappings match the actual behavior
      of xterm (a few come close, but do so by matching the terminfo
      descriptions rather than the programs).  In particular, the application
      keypad does not send vt100-style escapes.
  <li><A HREF="../vttest/vttest.html">vttest</A>) demonstrates that
      konsole does not properly ignore escape sequences
      to switch character sets that it does not support.
      Also, 
      the developers of konsole did use an old version of vttest, but
      that was to add a bogus Device Attributes response (claimed to
      be for "vt220", but not corresponding to any that DEC produced).
      They do not use the newer version of vttest (which was available more
      than a year before development of konsole began).
  <li>konsole implements several features from XFree86 xterm, but some are
      done incorrectly.
      In particular, the <a href="#xterm_tite">private setmode 1049</a>
      does not save and restore the cursor,
      causing the cursor to be in unexpected locations
      after exiting a fullscreen application such as vi.
</ul>

<H3><A NAME="bug_kterm">KTERM</A>
<A HREF="ftp://www.x.org/contrib/applications/kterm-6.2.0.tar.gz">download</A></H3>
KTerm stands for "Kanji term" (Japanese).
This is based on the X Consortium source, with the same bugs
(though the list of original authors has been removed; the modifications
that comprise kterm is relatively small).
<UL>
<LI>implements non-bce color model
<LI>implements status line, but uses non-DEC escape sequences for this.
</UL>
There is a variation of xvt (ancestor of rxvt) originally known as
<A NAME="bug_kvt">kvt</A>
bundled with
<a href="http://www.kde.org/">KDE</a>
which may be referred to as
"kterm", but I do not find it interesting,
other than to comment that it was a poor choice of name.

<H3><A NAME="bug_mlterm" HREF="http://mlterm.sourceforge.net/">MLTERM</A></H3>
Mlterm is not based on xterm or rxvt source,
though it implements many of their features.
It does fairly well with
<A HREF="../vttest/vttest.html">vttest</A>,
except for some odd misbehavior in
operations that save/restore the cursor position.

<H3><A NAME="bug_mterm">MTERM</A></H3>
There are a few variants of this: the xterm bundled with some Motif clients
is more common.
More interesting, however is one (not Motif)
which is not readily available any longer, attributed to "Der Mouse".
<blockquote>
   (mouse@Lightning.McRCIM.McGill.EDU)
   Available: larry.mcrcim.mcgill.edu (132.206.1.1) in
     /X/mterm.src/mterm.ball-o-wax.
</blockquote>
I saw only an incomplete version of this while it was advertised
in the mid-90's.
It is available by email from &lt;mouse@Rodents.Montreal.QC.CA&gt;.
This is not a patched version of xterm,
though it was apparently written, like rxvt, to emulate vt100's.
While it does have some interesting features (such as blinking characters),
overall it does not do as well with
<A HREF="../vttest/vttest.html">vttest</A>)
as the more widely known emulators.

<H3><A NAME="bug_mxterm">MXTERM</A></H3>
There are several variants on this: xterm adapted for Motif libraries.
I have seen none that work properly:
<UL>
<LI><a href="http://camms1.caos.kun.nl/~schaft/mxterm/mxterm.html">MXTERM:
a motif Xterm with character attributes color rendered</a>
I've noticed this one only recently.
It is a reworking of the earlier patches for color_xterm
(credited to Erik Fortune at SGI)
and the Motif widgets
(apparently first done by Ivan M. Hajadi at SGI in 1991,
but credited in this release to Mahesh Neelakanta, for Motif 1.2.4).
<LI><a href="http://www.muquit.com/muquit/software/ansi_xterm/ansi_xterm.html">ANSI Xterm with Motif Scrollbar</a>
Usually seen as the ansi-xterm-R6-motif-sb patch, I used this as the
starting point for changes to my #82 patch of xterm in August 1998.
<p>
The original patch changes only the scrollbars to Motif, leaving the
popup menus in Athena widgets.
That was not what I wanted.
My motivation for using Motif is not for performance or esthetics, of course,
but to make it simpler to build on hosts that have no Athena widgets installed.
<p>
I set those changes aside, having found (the hard way) that the Motif library
has hardcoded behavior regarding the control right-mouse button.
According to the O'Reilly book on Motif programming (volume 6), it does
a server grab when processing menus.
Making the menus behave just as in the Athena widgets can cause the
X server to hang.
(I was able to do this with both Lesstif and Motif libraries).
Given that, I decided to restructure the menus entirely, making a toolbar
which could support at compile-time either widget set.
<LI><a href="http://www.fh-wilhelmshaven.de/~akcaagaa/index_mxterm.html">mxterm</a>
This is a different reworking of the Motif widget patch,
using a 1993 version (ignoring the more recent 1994 patches noted above).
However, it appears to have the same technical defect that I noted above.
</UL>

<H3><A NAME="bug_nxterm">NXTERM</A></H3>
Distributed with Redhat Linux 5.2,
it is a repackaging of <A HREF="#bug_ansi_xterm">xterm-sb_right-ansi</A>, to use the
Xaw3d widget set.  This is based on the X Consortium X11R6 source, with the
same bugs.
<UL>
<LI>implements non-bce color model
<LI>does not implement SGR 39 and SGR 49, all attributes are reset when changing colors.
<LI>popup menus do not appear to work.
</UL>
Starting with Redhat 6.0, <em>nxterm</em> is the XFree86 3.3.6 xterm.
Unfortunately Redhat neglected to update their termcap for nxterm to match
the program.

<H3><A NAME="bug_rxvt">RXVT</A>
<A HREF="http://www.rxvt.org/">link</A></H3>
Rxvt's manual page states the following unqualified comment:
<blockquote>
       rxvt,  version  2.6.2, is a colour vt102 terminal emulator
       intended as an xterm(1) replacement for users who  do  not
       require  features  such  as  Tektronix  4014 emulation and
       toolkit-style configurability.  As  a  result,  rxvt  uses
       much  less  swap  space  --  a  significant advantage on a
       machine serving many X sessions.
</blockquote>
How much is <em>much less</em>?
Perhaps not as much as one would think from reading that.
The Tektronix emulation in xterm
(which has been optional since late 1997)
accounts for about 25kb of the code.
The toolkit-style configurability glibly referenced is the ability to
redefine keys on the keyboard without recompiling the program,
i.e., the <a href="#how2_fkeys">translations</a> resource.
The toolkit-style configurability
accounts for about 300kb, which does add up if you happen to be
running 50 xterm processes (i.e., about 10Mb).
Compared with something like GNOME Terminal, which takes 2-3 times,
or KDE konsole, which takes 15-20 times as much memory to run,
xterm and rxvt memory requirements are indistinguishable to the normal user.
<p>
These comments apply to versions of <EM>rxvt</EM> through 2.21:
<UL>
<LI>clearing the screen resets colors
<LI>does not have a delete key
<LI>the implementation of <code>ech</code> (erase characters) does not
follow DEC VT220 (also ISO 6429), causing applications using this function to
misbehave.
</UL>
A new version
(upgraded to an beta as of 2.6.PRE3, however, since it no longer dumps core in
<A HREF="../vttest/vttest.html">vttest</A>)
is reported to fix the <code>ech</code> bug.
However, it is less VT100-compatible than the earlier versions such as 2.21b
because it does not render reverse video (<code>DECSCNM</code>) properly.
All versions do not update the screen frequently enough, making animation
ineffective.
See <A HREF="../vttest/vttest.html">vttest</A>, tests 1 and 2.

<H3><A NAME="bug_xgterm">XGTERM</A>
<A HREF="ftp://iraf.noao.edu/iraf/x11iraf/">link</A></H3>
It has some features which are also in color_xterm:(non-bce ANSI color,
colorBD and colorUL resources, cursor warping, etc.
The main feature is its Tektronix graphics emulation,
which is the main reason for this particular program.
Neither program has a change-log, so it is not easy to say which
influenced the other.
<p>
That is from reading the source code.
However testing under Debian Linux, something is wrong with the resource
processing (neither popup menus nor colors work).

<H3><A NAME="bug_xiterm">XITERM</A>
<A HREF="ftp://metalab.unc.edu/pub/Linux/X11/terms/">link</A></H3>
This appears to be rxvt 2.20,
lightly reformatted,
with a few ifdef's changed.
<p>
That is, it was.
The name was later appropriated by a different
<a href="http://oss.software.ibm.com/linux/projects/iterm/">program</a>,
which also uses the name <code>iterm</code>.
Like gnome-terminal,
iterm aims to be an xterm-emulator
rather than a VT102- or VT220-emulator.
<p>
An earlier <a href="http://www.openi18n.org">attempt</a> by the same author
(the "CSI-xterm")
incorporates some of the changes I made for XFree86 xterm
via cut and paste
(but does not mention this in its README).
It is said to be the basis for Solaris 10 xterm.
<p>
Both have similar problems running
<A HREF="../vttest/vttest.html">vttest</A>.

<H2><A NAME="building_it">How do I build XTERM?</A></H2>
Building a copy of xterm is simple, provided that you have a development
configuration for X11:
<UL>
<LI>Header files and libraries.
If you do not have the header files (usually under /usr/include/X11) for
your system, you are better off building the libraries yourself.
Xterm can be built with either X11R5 or X11R6 libraries; however X11R6
requires much more data to be installed before xterm will run.
Xterm uses the <code>Xaw</code> library for popup menus.
<LI>imake and <EM>xmkmf</EM>.
These utilities produce a Makefile from the Imakefile.
They are not essential, but useful, particularly on systems with
unusual configurations.
</UL>
If you have a working <EM>xmkmf</EM> script (or correctly configured imake utility),
all you need to do is type
<PRE><code>
	xmkmf
	make
</code></PRE>
I have written a simple <EM>configure</EM> script for xterm which uses imake
(or <EM>xmkmf</EM>) to generate a Makefile from the Makefile.in.
I plan to restructure xterm to eliminate the hardcoded
<code>#ifdef</code>'s, replacing them with definitions that can be derived
with the configuration script.
The <EM>configure</EM> script is more flexible than <EM>xmkmf</EM>, since it
allows you to enable or disable a variety of features.
Type
<PRE>
	configure --help
</PRE>
to get a list of options.
<P>
Though I plan to replace the hardcoded ifdef's with
autoconfigured values, it will still continue to build properly with the imake environment,
since that is how large distributions incorporate xterm.

<H2><A NAME="report_bugs">How do I report bugs?</A></H2>
You should report bugs to
<A HREF="mailto:dickey@invisible-island.net">me</A>.
I also respond to bug reports in a number of bug-tracking systems,
though some are less open to searches than others.
See also
<A HREF="../scripts/readme.html">Analyzing problems with configure scripts</A>

<H1><A NAME="more_info">Additional Information</A></H1>
There appears to be no comprehensive source of information on xterm
better than the documentation which comes with the source code.
I have found Richard Shuford's
<a href="http://www.cs.utk.edu/~shuford/terminal_index.html">archive</a>
to be invaluable for notes on the DEC VT220 and related terminals.
Though not available at the time that I was collecting most of my notes,
<a href="http://vt100.net">VT100.net</a> is also a good source of primary
information.
<p>
The command-line options, X resources and similar configurable options
of xterm are documented in the manual page.
Control sequences, i.e., programming information are in the
<code>ctlseqs.ms</code> file which I bundle with the program source.
(It used to be in the same directory in the X distribution, but was moved
to a difference part of the tree some time ago).  Note that you must format
this file with different options than a manpage, e.g.,
<pre><code>
	tbl ctlseqs.ms | nroff -ms &gt;ctlseqs.txt
	tbl ctlseqs.ms | groff -ms &gt;ctlseqs.ps
</code></pre>
As a PostScript file, the individual letters of the control sequences are
all boxed, for emphasis, but I find the text file equally readable.

<H1><A NAME="future_work">Ongoing/future work</A></H1>
<UL>
<LI>soft (downloadable) fonts
<LI>search scrollback
It would be nice to be able to search the scrollback buffer.
<LI>printer interface
<P>
Done, except for the corresponding support in the VT52 emulation.
It would be nice to have a dialog to control this.
<LI>allow alternate libraries for popup-menus and dialogs
<P>
My configure script currently provides tests for the variations of Athena
widgets (Xaw3D, neXtaw).
I intend to make additional changes to support
<A href="#bug_mxterm">Motif scrollbars and menus</A>.
Motif requires a different style of interface for the menus:
binding a popup menu to control right mouse may cause the server to hang.
As an intermediate step, I implemented a toolbar for the Athena widgets.
In turn, that works well enough except with XFree86 4.x:
the Xaw library geometry management is broken.
(Other implementations of the Athena widgets work well enough).
<LI>popup window that shows hex code for content of a character cell
and hexadecimal keyboard entry for all Unicode characters (ISO 14755)
<LI>correct cut&amp;paste of TAB character
</UL>

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