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1 Copyright (C) 1993, 2001-2013 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 to
9 see what type of terminal the user is running on, searches for an elisp file
10 named "term/${TERM}.el", and if one exists, loads it. If Emacs finds no
11 suitable file, then it strips the last hyphen and what follows it from TERM,
12 and tries again. If that still doesn't yield a file, then the previous hyphen
13 is stripped, and so on until all hyphens are gone. For example, if the
14 terminal type is `aaa-48-foo', Emacs will try first `term/aaa-48-foo.el', then
15 `term/aaa-48.el' and finally `term/aaa.el'. Emacs stops searching at the
16 first file found, and will not load more than one file for any terminal. Note
17 that it is not an error if Emacs is unable to find a terminal initialization
18 file; in that case, it will simply proceed with the next step without loading
19 any files.
21 Once the file has been loaded (or the search failed), Emacs tries to call a
22 function named `terminal-init-TERMINALNAME' (eg `terminal-init-aaa-48' for the
23 `aaa-48' terminal) in order to initialize the terminal. Once again, if the
24 function is not found, Emacs strips the last component of the name and tries
25 again using the shorter name. This search is independent of the previous file
26 search, so that you can have terminal initialization functions for a family of
27 terminals collected in a single file named after the family name, and users
28 may put terminal initialization functions directly in their .emacs files.
30 Note that an individual terminal file is loaded only once in an Emacs
31 session; if the same terminal type is opened again, Emacs will simply call the
32 initialization function without reloading the file. Therefore, all the actual
33 initialization actions should be collected in terminal-init-* functions; the
34 file should not contain any top-level form that is not a function or variable
35 declaration. Simply loading the file should not have any side effect.
37 Similarly, the terminal initialization function is called only once on any
38 given terminal, when the first frame is created on it. The function is not
39 called for subsequent frames on the same terminal. Therefore, terminal-init-*
40 functions should only modify terminal-local variables (such as
41 `local-function-key-map') and terminal parameters. For example, it is not
42 correct to modify frame parameters, since the modifications will only be
43 applied for the first frame opened on the terminal.
46 When writing terminal packages, there are some things it is good to keep in
47 mind.
49 First, about keycap names. Your terminal package can create any keycap
50 cookies it likes, but there are good reasons to stick to the set recognized by
51 the X-windows code whenever possible. The key symbols recognized by Emacs
52 are listed in src/term.c; look for the string `keys' in that file.
54 For one thing, it means that you'll have the same Emacs key bindings on in
55 terminal mode as on an X console. If there are differences, you can bet
56 they'll frustrate you after you've forgotten about them.
58 For another, the X keysms provide a standard set of names that Emacs knows
59 about. It tries to bind many of them to useful things at startup, before your
60 .emacs is read (so you can override them). In some ways, the X keysym standard
61 is a admittedly poor one; it's incomplete, and not well matched to the set of
62 `virtual keys' that UNIX terminfo(3) provides. But, trust us, the alternatives
63 were worse.
65 This doesn't mean that if your terminal has a "Cokebottle" key you shouldn't
66 define a [cokebottle] keycap. But if you must define cookies that aren't in
67 that set, try to pattern them on the standard terminfo variable names for
68 clarity; also, for a fighting chance that your binding may be useful to someone
69 else someday.
71 For example, if your terminal has a `find' key, observe that terminfo
72 supports a key_find capability and call your cookie [find].
74 Here is a complete list, with corresponding X keysyms.
76 -----------------------------------------------------------------------------
77 Variable name cap X Keysym Description
78 -------------- --- ------------ -------------------------------------
79 key_down kd down Sent by terminal down arrow key
80 key_up ku up Sent by terminal up arrow key
81 key_left kl left Sent by terminal left arrow key
82 key_right kr right Sent by terminal right arrow key
83 key_home kh home Sent by home key.
84 key_backspace kb Sent by backspace key
85 key_dl kd deleteline Sent by delete line key.
86 key_il kA insertline Sent by insert line.
87 key_dc kD Sent by delete character key.
88 key_ic kI insertchar (1) Sent by ins char/enter ins mode key.
89 key_eic KM Sent by rmir or smir in insert mode.
90 key_clear kC Sent by clear screen or erase key.
91 key_eos kS Sent by clear-to-end-of-screen key.
92 key_eol kE Sent by clear-to-end-of-line key.
93 key_sf kF Sent by scroll-forward/down key
94 key_sr kR Sent by scroll-backward/up key
95 key_npage kN next (2) Sent by next-page key
96 key_ppage kP prior (2) Sent by previous-page key
97 key_stab kT Sent by set-tab key
98 key_ctab kt Sent by clear-tab key
99 key_catab ka Sent by clear-all-tabs key.
100 key_enter @8 kp-enter Enter/send (unreliable)
101 key_print %9 print print or copy
102 key_ll kH Sent by home-down key
103 key_a1 K1 kp-1 Upper left of keypad
104 key_a3 K3 kp-3 Upper right of keypad
105 key_b2 K2 kp-5 Center of keypad
106 key_c1 K4 kp-7 Lower left of keypad
107 key_c3 K5 kp-9 Lower right of keypad
108 key_btab kB backtab Back tab key
109 key_beg @1 begin beg(inning) key
110 key_cancel @2 cancel cancel key
111 key_close @3 close key
112 key_command @4 execute (3) cmd (command) key
113 key_copy @5 copy key
114 key_create @6 create key
115 key_end @7 end end key
116 key_exit @9 exit key
117 key_find @0 find key
118 key_help %1 help key
119 key_mark %2 mark key
120 key_message %3 message key
121 key_move %4 move key
122 key_next %5 next (2) next object key
123 key_open %6 open key
124 key_options %7 menu (3) options key
125 key_previous %8 previous (2) previous object key
126 key_redo %0 redo redo key
127 key_reference &1 ref(erence) key
128 key_refresh &2 refresh key
129 key_replace &3 replace key
130 key_restart &4 reset (3) restart key
131 key_resume &5 resume key
132 key_save &6 save key
133 key_sbeg &9 shifted beginning key
134 key_select *6 select select key
135 key_suspend &7 suspend key
136 key_undo &8 undo undo key
138 key_scancel &0 shifted cancel key
139 key_scommand *1 shifted command key
140 key_scopy *2 shifted copy key
141 key_screate *3 shifted create key
142 key_sdc *4 shifted delete char key
143 key_sdl *5 shifted delete line key
144 key_send *7 shifted end key
145 key_seol *8 shifted clear line key
146 key_sexit *9 shifted exit key
147 key_sf kF shifted find key
148 key_shelp #1 shifted help key
149 key_shome #2 shifted home key
150 key_sic #3 shifted input key
151 key_sleft #4 shifted left arrow key
152 key_smessage %a shifted message key
153 key_smove %b shifted move key
154 key_snext %c shifted next key
155 key_soptions %d shifted options key
156 key_sprevious %e shifted prev key
157 key_sprint %f shifted print key
158 key_sredo %g shifted redo key
159 key_sreplace %h shifted replace key
160 key_sright %i shifted right arrow
161 key_sresume %j shifted resume key
162 key_ssave !1 shifted save key
163 key_suspend !2 shifted suspend key
164 key_sundo !3 shifted undo key
166 key_f0 k0 f0 (4) function key 0
167 key_f1 k1 f1 function key 1
168 key_f2 k2 f2 function key 2
169 key_f3 k3 f3 function key 3
170 key_f4 k4 f4 function key 4
171 key_f5 k5 f5 function key 5
172 key_f6 k6 f6 function key 6
173 key_f7 k7 f7 function key 7
174 key_f8 k8 f8 function key 8
175 key_f9 k9 f9 function key 9
176 key_f10 k; f10 (4) function key 10
177 key_f11 F1 f11 function key 11
178 : : : :
179 key_f35 FP f35 function key 35
180 key_f36 FQ function key 36
181 : : : :
182 key_f64 k1 function key 64
184 (1) The terminfo documentation says this may be the 'insert character' or
185 `enter insert mode' key. Accordingly, key_ic is mapped to the `insertchar'
186 keysym if there is also a key_dc key; otherwise it's mapped to `insert'.
187 The presumption is that keyboards with `insert character' keys usually
188 have `delete character' keys paired with them.
190 (2) If there is no key_next key but there is a key_npage key, key_npage
191 will be bound to the `next' keysym. If there is no key_previous key but
192 there is a key_ppage key, key_ppage will be bound to the `previous' keysym.
194 (3) Sorry, these are not exact but they're the best we can do.
196 (4) The uses of the "k0" capability are inconsistent; sometimes it
197 describes F10, whereas othertimes it describes F0 and "k;" describes F10.
198 Emacs attempts to politely accommodate both systems by testing for
199 "k;", and if it is present, assuming that "k0" denotes F0, otherwise F10.
200 -----------------------------------------------------------------------------
202 The following X keysyms do *not* have terminfo equivalents. These are
203 the cookies your terminal package will have to set up itself, if you want them:
205 break
206 system
207 user
208 kp-backtab
209 kp-space
210 kp-tab
211 kp-f1
212 kp-f2
213 kp-f3
214 kp-f4
215 kp-multiply
216 kp-add
217 kp-separator
218 kp-subtract
219 kp-decimal
220 kp-divide
221 kp-0
222 kp-2
223 kp-4
224 kp-6
225 kp-8
226 kp-equal
228 In general, you should not bind any of the standard keysym names to
229 functions in a terminal package. There's code in loaddefs.el that does that;
230 the less people make exceptions to that, the more consistent an interface Emacs
231 will have across different keyboards. Those exceptions should go in your
232 .emacs file.
234 Finally, if you're using a USL UNIX or a Sun box or anything else with the
235 USL version of curses(3) on it, bear in mind that the original curses(3) had
236 (and still has) a very much smaller set of keycaps. In fact, the reliable
237 ones were just the arrow keys and the first ten function keys. If you care
238 about making your package portable to older Berkeley machines, don't count on
239 the setup code to bind anything else.
241 If your terminal's arrow key sequences are so funky that they conflict with
242 normal Emacs key bindings, the package should set up a function called
243 (enable-foo-arrow-keys), where `foo' becomes the terminal name, and leave
244 it up to the user's .emacs file whether to call it.
246 Before writing a terminal-support package, it's a good idea to read the
247 existing ones and learn the common conventions.
249 \f
250 This file is part of GNU Emacs.
252 GNU Emacs is free software: you can redistribute it and/or modify
253 it under the terms of the GNU General Public License as published by
254 the Free Software Foundation, either version 3 of the License, or
255 (at your option) any later version.
257 GNU Emacs is distributed in the hope that it will be useful,
258 but WITHOUT ANY WARRANTY; without even the implied warranty of
259 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
260 GNU General Public License for more details.
262 You should have received a copy of the GNU General Public License
263 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.