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1 Copyright (C) 1993, 2001-2017 Free Software Foundation, Inc.
2 See the end of the file for license conditions.
5 This directory contains files of elisp that customize Emacs for certain
6 terminal types.
8 When Emacs opens a new terminal, it checks the TERM environment variable
9 to see what type of terminal the user is running on. (If there is an entry
10 for TERM in the 'term-file-aliases' variable, Emacs uses the associated value
11 in place of TERM in the following.) Emacs searches for an elisp file named
12 "term/${TERM}.el", and if one exists, loads it. If Emacs finds no
13 suitable file, then it strips the last hyphen and what follows it from TERM,
14 and tries again. If that still doesn't yield a file, then the previous hyphen
15 is stripped, and so on until all hyphens are gone. For example, if the
16 terminal type is 'aaa-48-foo', Emacs will try first 'term/aaa-48-foo.el', then
17 'term/aaa-48.el' and finally 'term/aaa.el'. Emacs stops searching at the
18 first file found, and will not load more than one file for any terminal. Note
19 that it is not an error if Emacs is unable to find a terminal initialization
20 file; in that case, it will simply proceed with the next step without loading
21 any files.
23 Once the file has been loaded (or the search failed), Emacs tries to call a
24 function named 'terminal-init-TERMINALNAME' (eg 'terminal-init-aaa-48' for the
25 'aaa-48' terminal) in order to initialize the terminal. Once again, if the
26 function is not found, Emacs strips the last component of the name and tries
27 again using the shorter name. This search is independent of the previous file
28 search, so that you can have terminal initialization functions for a family of
29 terminals collected in a single file named after the family name, and users
30 may put terminal initialization functions directly in their .emacs files.
32 Note that an individual terminal file is loaded only once in an Emacs
33 session; if the same terminal type is opened again, Emacs will simply call the
34 initialization function without reloading the file. Therefore, all the actual
35 initialization actions should be collected in terminal-init-* functions; the
36 file should not contain any top-level form that is not a function or variable
37 declaration. Simply loading the file should not have any side effect.
39 Similarly, the terminal initialization function is called only once on any
40 given terminal, when the first frame is created on it. The function is not
41 called for subsequent frames on the same terminal. Therefore, terminal-init-*
42 functions should only modify terminal-local variables (such as
43 'local-function-key-map') and terminal parameters. For example, it is not
44 correct to modify frame parameters, since the modifications will only be
45 applied for the first frame opened on the terminal.
48 When writing terminal packages, there are some things it is good to keep in
49 mind.
51 First, about keycap names. Your terminal package can create any keycap
52 cookies it likes, but there are good reasons to stick to the set recognized by
53 the X-windows code whenever possible. The key symbols recognized by Emacs
54 are listed in src/term.c; look for the string 'keys' in that file.
56 For one thing, it means that you'll have the same Emacs key bindings on in
57 terminal mode as on an X console. If there are differences, you can bet
58 they'll frustrate you after you've forgotten about them.
60 For another, the X keysyms provide a standard set of names that Emacs knows
61 about. It tries to bind many of them to useful things at startup, before your
62 .emacs is read (so you can override them). In some ways, the X keysym standard
63 is a admittedly poor one; it's incomplete, and not well matched to the set of
64 'virtual keys' that UNIX terminfo(3) provides. But, trust us, the alternatives
65 were worse.
67 This doesn't mean that if your terminal has a "Cokebottle" key you shouldn't
68 define a [cokebottle] keycap. But if you must define cookies that aren't in
69 that set, try to pattern them on the standard terminfo variable names for
70 clarity; also, for a fighting chance that your binding may be useful to someone
71 else someday.
73 For example, if your terminal has a 'find' key, observe that terminfo
74 supports a key_find capability and call your cookie [find].
76 Here is a complete list, with corresponding X keysyms.
78 -----------------------------------------------------------------------------
79 Variable name cap X Keysym Description
80 -------------- --- ------------ -------------------------------------
81 key_down kd down Sent by terminal down arrow key
82 key_up ku up Sent by terminal up arrow key
83 key_left kl left Sent by terminal left arrow key
84 key_right kr right Sent by terminal right arrow key
85 key_home kh home Sent by home key.
86 key_backspace kb Sent by backspace key
87 key_dl kd deleteline Sent by delete line key.
88 key_il kA insertline Sent by insert line.
89 key_dc kD Sent by delete character key.
90 key_ic kI insertchar (1) Sent by ins char/enter ins mode key.
91 key_eic KM Sent by rmir or smir in insert mode.
92 key_clear kC Sent by clear screen or erase key.
93 key_eos kS Sent by clear-to-end-of-screen key.
94 key_eol kE Sent by clear-to-end-of-line key.
95 key_sf kF Sent by scroll-forward/down key
96 key_sr kR Sent by scroll-backward/up key
97 key_npage kN next (2) Sent by next-page key
98 key_ppage kP prior (2) Sent by previous-page key
99 key_stab kT Sent by set-tab key
100 key_ctab kt Sent by clear-tab key
101 key_catab ka Sent by clear-all-tabs key.
102 key_enter @8 kp-enter Enter/send (unreliable)
103 key_print %9 print print or copy
104 key_ll kH Sent by home-down key
105 key_a1 K1 kp-1 Upper left of keypad
106 key_a3 K3 kp-3 Upper right of keypad
107 key_b2 K2 kp-5 Center of keypad
108 key_c1 K4 kp-7 Lower left of keypad
109 key_c3 K5 kp-9 Lower right of keypad
110 key_btab kB backtab Back tab key
111 key_beg @1 begin beg(inning) key
112 key_cancel @2 cancel cancel key
113 key_close @3 close key
114 key_command @4 execute (3) cmd (command) key
115 key_copy @5 copy key
116 key_create @6 create key
117 key_end @7 end end key
118 key_exit @9 exit key
119 key_find @0 find key
120 key_help %1 help key
121 key_mark %2 mark key
122 key_message %3 message key
123 key_move %4 move key
124 key_next %5 next (2) next object key
125 key_open %6 open key
126 key_options %7 menu (3) options key
127 key_previous %8 previous (2) previous object key
128 key_redo %0 redo redo key
129 key_reference &1 ref(erence) key
130 key_refresh &2 refresh key
131 key_replace &3 replace key
132 key_restart &4 reset (3) restart key
133 key_resume &5 resume key
134 key_save &6 save key
135 key_sbeg &9 shifted beginning key
136 key_select *6 select select key
137 key_suspend &7 suspend key
138 key_undo &8 undo undo key
140 key_scancel &0 shifted cancel key
141 key_scommand *1 shifted command key
142 key_scopy *2 shifted copy key
143 key_screate *3 shifted create key
144 key_sdc *4 shifted delete char key
145 key_sdl *5 shifted delete line key
146 key_send *7 shifted end key
147 key_seol *8 shifted clear line key
148 key_sexit *9 shifted exit key
149 key_sf kF shifted find key
150 key_shelp #1 shifted help key
151 key_shome #2 shifted home key
152 key_sic #3 shifted input key
153 key_sleft #4 shifted left arrow key
154 key_smessage %a shifted message key
155 key_smove %b shifted move key
156 key_snext %c shifted next key
157 key_soptions %d shifted options key
158 key_sprevious %e shifted prev key
159 key_sprint %f shifted print key
160 key_sredo %g shifted redo key
161 key_sreplace %h shifted replace key
162 key_sright %i shifted right arrow
163 key_sresume %j shifted resume key
164 key_ssave !1 shifted save key
165 key_suspend !2 shifted suspend key
166 key_sundo !3 shifted undo key
168 key_f0 k0 f0 (4) function key 0
169 key_f1 k1 f1 function key 1
170 key_f2 k2 f2 function key 2
171 key_f3 k3 f3 function key 3
172 key_f4 k4 f4 function key 4
173 key_f5 k5 f5 function key 5
174 key_f6 k6 f6 function key 6
175 key_f7 k7 f7 function key 7
176 key_f8 k8 f8 function key 8
177 key_f9 k9 f9 function key 9
178 key_f10 k; f10 (4) function key 10
179 key_f11 F1 f11 function key 11
180 : : : :
181 key_f35 FP f35 function key 35
182 key_f36 FQ function key 36
183 : : : :
184 key_f64 k1 function key 64
186 (1) The terminfo documentation says this may be the 'insert character' or
187 'enter insert mode' key. Accordingly, key_ic is mapped to the 'insertchar'
188 keysym if there is also a key_dc key; otherwise it's mapped to 'insert'.
189 The presumption is that keyboards with 'insert character' keys usually
190 have 'delete character' keys paired with them.
192 (2) If there is no key_next key but there is a key_npage key, key_npage
193 will be bound to the 'next' keysym. If there is no key_previous key but
194 there is a key_ppage key, key_ppage will be bound to the 'previous' keysym.
196 (3) Sorry, these are not exact but they're the best we can do.
198 (4) The uses of the "k0" capability are inconsistent; sometimes it
199 describes F10, whereas othertimes it describes F0 and "k;" describes F10.
200 Emacs attempts to politely accommodate both systems by testing for
201 "k;", and if it is present, assuming that "k0" denotes F0, otherwise F10.
202 -----------------------------------------------------------------------------
204 The following X keysyms do *not* have terminfo equivalents. These are
205 the cookies your terminal package will have to set up itself, if you want them:
207 break
208 system
209 user
210 kp-backtab
211 kp-space
212 kp-tab
213 kp-f1
214 kp-f2
215 kp-f3
216 kp-f4
217 kp-multiply
218 kp-add
219 kp-separator
220 kp-subtract
221 kp-decimal
222 kp-divide
223 kp-0
224 kp-2
225 kp-4
226 kp-6
227 kp-8
228 kp-equal
230 In general, you should not bind any of the standard keysym names to
231 functions in a terminal package. There's code in loaddefs.el that does that;
232 the less people make exceptions to that, the more consistent an interface Emacs
233 will have across different keyboards. Those exceptions should go in your
234 .emacs file.
236 Finally, if you're using a USL UNIX or a Sun box or anything else with the
237 USL version of curses(3) on it, bear in mind that the original curses(3) had
238 (and still has) a very much smaller set of keycaps. In fact, the reliable
239 ones were just the arrow keys and the first ten function keys. If you care
240 about making your package portable to older Berkeley machines, don't count on
241 the setup code to bind anything else.
243 If your terminal's arrow key sequences are so funky that they conflict with
244 normal Emacs key bindings, the package should set up a function called
245 (enable-foo-arrow-keys), where 'foo' becomes the terminal name, and leave
246 it up to the user's .emacs file whether to call it.
248 Before writing a terminal-support package, it's a good idea to read the
249 existing ones and learn the common conventions.
251 \f
252 This file is part of GNU Emacs.
254 GNU Emacs is free software: you can redistribute it and/or modify
255 it under the terms of the GNU General Public License as published by
256 the Free Software Foundation, either version 3 of the License, or
257 (at your option) any later version.
259 GNU Emacs is distributed in the hope that it will be useful,
260 but WITHOUT ANY WARRANTY; without even the implied warranty of
261 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
262 GNU General Public License for more details.
264 You should have received a copy of the GNU General Public License
265 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.