1ReadKey(3)            User Contributed Perl Documentation           ReadKey(3)
2
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4

NAME

6       Term::ReadKey - A perl module for simple terminal control
7

SYNOPSIS

9           use Term::ReadKey;
10           ReadMode 4; # Turn off controls keys
11           while (not defined ($key = ReadKey(-1))) {
12               # No key yet
13           }
14           print "Get key $key\n";
15           ReadMode 0; # Reset tty mode before exiting
16

DESCRIPTION

18       Term::ReadKey is a compiled perl module dedicated to providing simple
19       control over terminal driver modes (cbreak, raw, cooked, etc.,) support
20       for non-blocking reads, if the architecture allows, and some
21       generalized handy functions for working with terminals. One of the main
22       goals is to have the functions as portable as possible, so you can just
23       plug in "use Term::ReadKey" on any architecture and have a good
24       likelihood of it working.
25
26       Version 2.30.01: Added handling of arrows, page up/down, home/end,
27       insert/delete keys under Win32. These keys emit xterm-compatible
28       sequences.  Works with Term::ReadLine::Perl.
29
30       ReadMode MODE [, Filehandle]
31           Takes an integer argument or a string synonym (case insensitive),
32           which can currently be one of the following values:
33
34               INT   SYNONYM    DESCRIPTION
35
36               0    'restore'   Restore original settings.
37
38               1    'normal'    Change to what is commonly the default mode,
39                                echo on, buffered, signals enabled, Xon/Xoff
40                                possibly enabled, and 8-bit mode possibly disabled.
41
42               2    'noecho'    Same as 1, just with echo off. Nice for
43                                reading passwords.
44
45               3    'cbreak'    Echo off, unbuffered, signals enabled, Xon/Xoff
46                                possibly enabled, and 8-bit mode possibly enabled.
47
48               4    'raw'       Echo off, unbuffered, signals disabled, Xon/Xoff
49                                disabled, and 8-bit mode possibly disabled.
50
51               5    'ultra-raw' Echo off, unbuffered, signals disabled, Xon/Xoff
52                                disabled, 8-bit mode enabled if parity permits,
53                                and CR to CR/LF translation turned off.
54
55           These functions are automatically applied to the STDIN handle if no
56           other handle is supplied. Modes 0 and 5 have some special
57           properties worth mentioning: not only will mode 0 restore original
58           settings, but it cause the next ReadMode call to save a new set of
59           default settings. Mode 5 is similar to mode 4, except no CR/LF
60           translation is performed, and if possible, parity will be disabled
61           (only if not being used by the terminal, however. It is no
62           different from mode 4 under Windows.)
63
64           If you just need to read a key at a time, then modes 3 or 4 are
65           probably sufficient. Mode 4 is a tad more flexible, but needs a bit
66           more work to control. If you use ReadMode 3, then you should
67           install a SIGINT or END handler to reset the terminal (via ReadMode
68           0) if the user aborts the program via "^C". (For any mode, an END
69           handler consisting of "ReadMode 0" is actually a good idea.)
70
71           If you are executing another program that may be changing the
72           terminal mode, you will either want to say
73
74               ReadMode 1;             # same as ReadMode 'normal'
75               system('someprogram');
76               ReadMode 1;
77
78           which resets the settings after the program has run, or:
79
80               $somemode=1;
81               ReadMode 0;             # same as ReadMode 'restore'
82               system('someprogram');
83               ReadMode 1;
84
85           which records any changes the program may have made, before
86           resetting the mode.
87
88       ReadKey MODE [, Filehandle]
89           Takes an integer argument, which can currently be one of the
90           following values:
91
92               0    Perform a normal read using getc
93               -1   Perform a non-blocked read
94               >0   Perform a timed read
95
96           If the filehandle is not supplied, it will default to STDIN. If
97           there is nothing waiting in the buffer during a non-blocked read,
98           then undef will be returned.  In most situations, you will probably
99           want to use "ReadKey -1".
100
101           NOTE that if the OS does not provide any known mechanism for non-
102           blocking reads, then a "ReadKey -1" can die with a fatal error.
103           This will hopefully not be common.
104
105           If MODE is greater then zero, then ReadKey will use it as a timeout
106           value in seconds (fractional seconds are allowed), and won't return
107           "undef" until that time expires.
108
109           NOTE, again, that some OS's may not support this timeout behaviour.
110
111           If MODE is less then zero, then this is treated as a timeout of
112           zero, and thus will return immediately if no character is waiting.
113           A MODE of zero, however, will act like a normal getc.
114
115           NOTE, there are currently some limitations with this call under
116           Windows.  It may be possible that non-blocking reads will fail when
117           reading repeating keys from more then one console.
118
119       ReadLine MODE [, Filehandle]
120           Takes an integer argument, which can currently be one of the
121           following values:
122
123               0    Perform a normal read using scalar(<FileHandle>)
124               -1   Perform a non-blocked read
125               >0   Perform a timed read
126
127           If there is nothing waiting in the buffer during a non-blocked
128           read, then undef will be returned.
129
130           NOTE, that if the OS does not provide any known mechanism for non-
131           blocking reads, then a "ReadLine 1" can die with a fatal error.
132           This will hopefully not be common.
133
134           NOTE that a non-blocking test is only performed for the first
135           character in the line, not the entire line.  This call will
136           probably not do what you assume, especially with "ReadMode" MODE
137           values higher then 1. For example, pressing Space and then
138           Backspace would appear to leave you where you started, but any
139           timeouts would now be suspended.
140
141           This call is currently not available under Windows.
142
143       GetTerminalSize [Filehandle]
144           Returns either an empty array if this operation is unsupported, or
145           a four element array containing: the width of the terminal in
146           characters, the height of the terminal in character, the width in
147           pixels, and the height in pixels. (The pixel size will only be
148           valid in some environments.)
149
150           NOTE, under Windows, this function must be called with an output
151           filehandle, such as "STDOUT", or a handle opened to "CONOUT$".
152
153       SetTerminalSize WIDTH,HEIGHT,XPIX,YPIX [, Filehandle]
154           Return -1 on failure, 0 otherwise.
155
156           NOTE that this terminal size is only for informative value, and
157           changing the size via this mechanism will not change the size of
158           the screen. For example, XTerm uses a call like this when it
159           resizes the screen. If any of the new measurements vary from the
160           old, the OS will probably send a SIGWINCH signal to anything
161           reading that tty or pty.
162
163           This call does not work under Windows.
164
165       GetSpeed [, Filehandle]
166           Returns either an empty array if the operation is unsupported, or a
167           two value array containing the terminal in and out speeds, in
168           decimal. E.g, an in speed of 9600 baud and an out speed of 4800
169           baud would be returned as (9600,4800). Note that currently the in
170           and out speeds will always be identical in some OS's.
171
172           No speeds are reported under Windows.
173
174       GetControlChars [, Filehandle]
175           Returns an array containing key/value pairs suitable for a hash.
176           The pairs consist of a key, the name of the control
177           character/signal, and the value of that character, as a single
178           character.
179
180           This call does nothing under Windows.
181
182           Each key will be an entry from the following list:
183
184                   DISCARD
185                   DSUSPEND
186                   EOF
187                   EOL
188                   EOL2
189                   ERASE
190                   ERASEWORD
191                   INTERRUPT
192                   KILL
193                   MIN
194                   QUIT
195                   QUOTENEXT
196                   REPRINT
197                   START
198                   STATUS
199                   STOP
200                   SUSPEND
201                   SWITCH
202                   TIME
203
204           Thus, the following will always return the current interrupt
205           character, regardless of platform.
206
207                   %keys = GetControlChars;
208                   $int = $keys{INTERRUPT};
209
210       SetControlChars [, Filehandle]
211           Takes an array containing key/value pairs, as a hash will produce.
212           The pairs should consist of a key that is the name of a legal
213           control character/signal, and the value should be either a single
214           character, or a number in the range 0-255. SetControlChars will die
215           with a runtime error if an invalid character name is passed or
216           there is an error changing the settings. The list of valid names is
217           easily available via
218
219                   %cchars = GetControlChars();
220                   @cnames = keys %cchars;
221
222           This call does nothing under Windows.
223

AUTHOR

225       Kenneth Albanowski <kjahds@kjahds.com>
226
227       Currently maintained by Jonathan Stowe <jns@gellyfish.co.uk>
228

SUPPORT

230       The code is maintained at
231
232            https://github.com/jonathanstowe/TermReadKey
233
234       Please feel free to fork and suggest patches.
235

LICENSE

237       Prior to the 2.31 release the license statement was:
238
239        Copyright (C) 1994-1999 Kenneth Albanowski.
240                      2001-2005 Jonathan Stowe and others
241
242                      Unlimited distribution and/or modification is allowed as long as this
243                      copyright notice remains intact.
244
245       And was only stated in the README file.
246
247       Because I believe the original author's intent was to be more open than
248       the other commonly used licenses I would like to leave that in place.
249       However if you or your lawyers require something with some more words
250       you can optionally choose to license this under the standard Perl
251       license:
252
253             This module is free software; you can redistribute it and/or modify it
254             under the terms of the Artistic License. For details, see the full
255             text of the license in the file "Artistic" that should have been provided
256             with the version of perl you are using.
257
258             This program is distributed in the hope that it will be useful, but
259             without any warranty; without even the implied warranty of merchantability
260             or fitness for a particular purpose.
261
262
263
264perl v5.32.1                      2021-01-27                        ReadKey(3)
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