readkey(3)

NAME

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

SYNOPSIS

use Term::ReadKey;
ReadMode 4; # Turn off controls keys
while (not defined ($key = ReadKey(-1)) {
        # No key yet
}
print "Get key $key0;
ReadMode 0; # Reset tty mode before exiting

DESCRIPTION

Term::ReadKey is a compiled perl module dedicated to pro
viding simple control over terminal driver modes (cbreak,
raw, cooked, etc.,) support for non-blocking reads, if the
architecture allows, and some generalized handy functions
for working with terminals. One of the main goals is to
have the functions as portable as possible, so you can
just plug in "use Term::ReadKey" on any architecture and
have a good likelyhood of it working.

ReadMode MODE [, Filehandle]

Takes an integer argument, which can currently be
one of the following values:

0 Restore original settings.
1 Change to cooked mode.
2 Change to cooked mode with echo off.

(Good for passwords)

3 Change to cbreak mode.
4 Change to raw mode.
5 Change to ultra-raw mode.

(LF to CR/LF translation turned off)

Or, you may use the synonyms:

restore
normal
noecho
cbreak
raw
ultra-raw

These functions are automatically applied to the
STDIN handle if no other handle is supplied. Modes
0 and 5 have some special properties worth men
tioning: not only will mode 0 restore original
settings, but it cause the next ReadMode call to
save a new set of default settings. Mode 5 is sim
ilar to mode 4, except no CR/LF translation is
performed, and if possible, parity will be dis
abled (only if not being used by the terminal,
however. It is no different from mode 4 under Win
dows.)

If you are executing another program that may be
changing the terminal mode, you will either want
to say

ReadMode 1
system('someprogram');
ReadMode 1;

which resets the settings after the program has
run, or:

$somemode=1;
ReadMode 0;
system('someprogram');
ReadMode 1;

which records any changes the program may have
made, before resetting the mode.

ReadKey MODE [, Filehandle]

Takes an integer argument, which can currently be
one of the following values:

0 Perform a normal read using getc
-1 Perform a non-blocked read
>0 Perform a timed read

(If the filehandle is not supplied, it will
default to STDIN.) If there is nothing waiting in
the buffer during a non-blocked read, then undef
will be returned. Note that if the OS does not
provide any known mechanism for non-blocking
reads, then a "ReadKey -1" can die with a fatal
error. This will hopefully not be common.

If MODE is greater then zero, then ReadKey will
use it as a timeout value in seconds (fractional
seconds are allowed), and won't return "undef"
until that time expires. (Note, again, that some
OS's may not support this timeout behaviour.) If
MODE is less then zero, then this is treated as a
timeout of zero, and thus will return immediately
if no character is waiting. A MODE of zero, how
ever, will act like a normal getc.

There are currently some limitations with this
call under Windows. It may be possible that nonblocking reads will fail when reading repeating
keys from more then one console.

ReadLine MODE [, Filehandle]

Takes an integer argument, which can currently be
one of the following values:

0 Perform a normal read using scalar(<File

Handle>)
-1 Perform a non-blocked read
>0 Perform a timed read

If there is nothing waiting in the buffer during a
non-blocked read, then undef will be returned.
Note that if the OS does not provide any known
mechanism for non-blocking reads, then a "ReadLine
1" can die with a fatal error. This will hopefully
not be common. Note that a non-blocking test is
only performed for the first character in the
line, not the entire line. This call will proba
bly not do what you assume, especially with Read
Mode's higher then 1. For example, pressing Space
and then Backspace would appear to leave you where
you started, but any timeouts would now be
suspended.

This call is currently not available under Win
dows.

GetTerminalSize [Filehandle]

Returns either an empty array if this operation is
unsupported, or a four element array containing:
the width of the terminal in characters, the
height of the terminal in character, the width in
pixels, and the height in pixels. (The pixel size
will only be valid in some environments.)

Under Windows, this function must be called with
an "output" filehandle, such as STDOUT, or a han
dle opened to CONOUT$.

SetTerminalSize WIDTH,HEIGHT,XPIX,YPIX [, Filehandle]

Return -1 on failure, 0 otherwise. Note that this
terminal size is only for informative value, and changing the size via this mechanism will not
change the size of the screen. For example, XTerm
uses a call like this when it resizes the screen.
If any of the new measurements vary from the old,
the OS will probably send a SIGWINCH signal to
anything reading that tty or pty.

This call does not work under Windows.

GetSpeeds [, Filehandle]

Returns either an empty array if the operation is
unsupported, or a two value array containing the
terminal in and out speeds, in decimal. E.g, an in speed of 9600 baud and an out speed of 4800 baud
would be returned as (9600,4800). Note that cur
rently the in and out speeds will always be iden
tical in some OS's. No speeds are reported under
Windows.

GetControlChars [, Filehandle]

Returns an array containing key/value pairs suit
able for a hash. The pairs consist of a key, the
name of the control character/signal, and the
value of that character, as a single character.
This call does nothing under Windows.

Each key will be an entry from the following list:

DISCARD
DSUSPEND
EOF
EOL
EOL2
ERASE
ERASEWORD
INTERRUPT
KILL
MIN
QUIT
QUOTENEXT
REPRINT
START
STATUS
STOP
SUSPEND
SWITCH
TIME

Thus, the following will always return the current
interrupt character, regardless of platform.

%keys = GetControlChars;
$int = $keys{INTERRUPT};

SetControlChars [, Filehandle]

Takes an array containing key/value pairs, as a
hash will produce. The pairs should consist of a
key that is the name of a legal control charac
ter/signal, and the value should be either a sin
gle character, or a number in the range 0-255.
SetControlChars will die with a runtime error if
an invalid character name is passed or there is an
error changing the settings. The list of valid
names is easily available via

%cchars = GetControlChars();
@cnames = keys %cchars;

This call does nothing under Windows.

AUTHOR

Kenneth Albanowski <kjahds@kjahds.com>

Currently maintained by Jonathan Stowe <jns@gellyfish.com>

perl v5.8.0 2002-07-28 ReadKey(3)