oracular (3) IO::Termios.3pm.gz
NAME
"IO::Termios" - supply termios(3) methods to "IO::Handle" objects
SYNOPSIS
use IO::Termios;
my $term = IO::Termios->open( "/dev/ttyS0", "9600,8,n,1" )
or die "Cannot open ttyS0 - $!";
$term->print( "Hello world\n" ); # Still an IO::Handle
while( <$term> ) {
print "A line from ttyS0: $_";
}
DESCRIPTION
This class extends the generic "IO::Handle" object class by providing methods which access the system's
terminal control termios(3) operations. These methods are primarily of interest when dealing with TTY
devices, including serial ports.
The flag-setting methods will apply to any TTY device, such as a pseudo-tty, and are useful for
controlling such flags as the "ECHO" flag, to disable local echo.
my $stdin = IO::Termios->new( \*STDIN );
$stdin->setflag_echo( 0 );
When dealing with a serial port the line mode method is useful for setting the basic serial parameters
such as baud rate, and the modem line control methods can be used to access the hardware handshaking
lines.
my $ttyS0 = IO::Termios->open( "/dev/ttyS0" );
$ttyS0->set_mode( "19200,8,n,1" );
$ttyS0->set_modem({ dsr => 1, cts => 1 });
Upgrading STDIN/STDOUT/STDERR
If you pass the "-upgrade" option at "import" time, any of STDIN, STDOUT or STDERR that are found to be
TTY wrappers are automatically upgraded into "IO::Termios" instances.
use IO::Termios -upgrade;
STDIN->setflag_echo(0);
Arbitrary Baud Rates on Linux
Linux supports a non-POSIX extension to the usual "termios" interface, which allows arbitrary baud rates
to be set. "IO::Termios" can automatically make use of this ability if the Linux::Termios2 module is
installed. If so, this will be used automatically and transparently, to allow the "set*baud" methods to
set any rate allowed by the kernel/driver. If not, then only the POSIX-compatible rates may be used.
CONSTRUCTORS
new
$term = IO::Termios->new();
Construct a new "IO::Termios" object around the terminal for the program. This is found by checking if
any of "STDIN", "STDOUT" or "STDERR" are a terminal. The first one that's found is used. An error occurs
if no terminal can be found by this method.
new (handle)
$term = IO::Termios->new( $handle );
Construct a new "IO::Termios" object around the given filehandle.
open
$term = IO::Termios->open( $path, $modestr, $flags );
Open the given path, and return a new "IO::Termios" object around the filehandle. If the "open" call
fails, "undef" is returned.
If $modestr is provided, the constructor will pass it to the "set_mode" method before returning.
If $flags is provided, it will be passed on to the underlying sysopen() call used to open the filehandle.
It should contain a bitwise-or combination of "O_*" flags from the Fcntl module - for example "O_NOCTTY"
or "O_NDELAY". The value "O_RDWR" will be added to this; the caller does not need to specify it directly.
For example:
use Fcntl qw( O_NOCTTY O_NDELAY );
$term = IO::Termios->open( "/dev/ttyS0", O_NOCTTY|O_NDELAY );
$term->setflag_clocal( 1 );
$term->blocking( 1 );
METHODS
getattr
$attrs = $term->getattr;
Makes a tcgetattr() call on the underlying filehandle, and returns a "IO::Termios::Attrs" object.
If the tcgetattr() call fails, "undef" is returned.
setattr
$term->setattr( $attrs );
Makes a tcsetattr() call on the underlying file handle, setting attributes from the given
"IO::Termios::Attrs" object.
If the tcsetattr() call fails, "undef" is returned. Otherwise, a true value is returned.
set_mode
get_mode
$term->set_mode( $modestr );
$modestr = $term->get_mode;
Accessor for the derived "mode string", which is a comma-joined concatenation of the baud rate, character
size, parity mode, and stop size in a format such as
19200,8,n,1
When setting the mode string, trailing components may be omitted meaning their value will not be
affected.
tiocmget
tiocmset
$bits = $term->tiocmget;
$term->tiocmset( $bits );
Accessor for the modem line control bits. Takes or returns a bitmask of values.
tiocmbic
tiocmbis
$term->tiocmbic( $bits );
$term->tiocmbis( $bits );
Bitwise mutator methods for the modem line control bits. "tiocmbic" will clear just the bits provided and
leave the others unchanged; "tiocmbis" will set them.
get_modem
$flags = $term->get_modem;
Returns a hash reference containing named flags corresponding to the modem line control bits. Any bit
that is set will yield a key in the returned hash of the same name. The bit names are
dtr dsr rts cts cd ri
set_modem
$term->set_modem( $flags );
Changes the modem line control bit flags as given by the hash reference. Each bit to be changed should be
represented by a key in the $flags hash of the names given above. False values will be cleared, true
values will be set. Other flags will not be altered.
getmodem_BIT
setmodem_BIT
$set = $term->getmodem_BIT;
$term->setmodem_BIT( $set );
Accessor methods for each of the modem line control bits. A set of methods exists for each of the named
modem control bits given above.
FLAG-ACCESSOR METHODS
Theses methods are implemented in terms of the lower level methods, but provide an interface which is
more abstract, and easier to re-implement on other non-POSIX systems. These should be used in preference
to the lower ones.
For efficiency, when getting or setting a large number of flags, it may be more efficient to call
"getattr", then operate on the returned object, before possibly passing it to "setattr". The returned
"IO::Termios::Attrs" object supports the same methods as documented here.
The following two sections of code are therefore equivalent, though the latter is more efficient as it
only calls "setattr" once.
$term->setbaud( 38400 );
$term->setcsize( 8 );
$term->setparity( 'n' );
$term->setstop( 1 );
my $attrs = $term->getattr;
$attrs->setbaud( 38400 );
$attrs->setcsize( 8 );
$attrs->setparity( 'n' );
$attrs->setstop( 1 );
$term->setattr( $attrs );
However, a convenient shortcut method is provided for the common case of setting the baud rate, character
size, parity and stop size all at the same time. This is "set_mode":
$term->set_mode( "38400,8,n,1" );
getibaud
getobaud
setibaud
setobaud
setbaud
$baud = $term->getibaud;
$baud = $term->getobaud;
$term->setibaud( $baud );
$term->setobaud( $baud );
$term->setbaud( $baud );
Convenience accessors for the "ispeed" and "ospeed". $baud is an integer directly giving the line rate,
instead of one of the "Bnnn" constants.
getcsize
setcsize
$bits = $term->getcsize;
$term->setcsize( $bits );
Convenience accessor for the "CSIZE" bits of "c_cflag". $bits is an integer 5 to 8.
getparity
setparity
$parity = $term->getparity;
$term->setparity( $parity );
Convenience accessor for the "PARENB" and "PARODD" bits of "c_cflag". $parity is "n", "o" or "e".
getstop
setstop
$stop = $term->getstop;
$term->setstop( $stop );
Convenience accessor for the "CSTOPB" bit of "c_cflag". $stop is 1 or 2.
cfmakeraw
$term->cfmakeraw;
Since version 0.07.
Adjusts several bit flags to put the terminal into a "raw" mode. Input is available a character at a
time, echo is disabled, and all special processing of input and output characters is disabled.
getflag_FLAG
setflag_FLAG
$mode = $term->getflag_FLAG;
$term->setflag_FLAG( $mode );
Accessors for various control flags. The following methods are defined for specific flags:
inlcr
Since version 0.09.
The "INLCR" bit of the "c_iflag". This translates NL to CR on input.
igncr
Since version 0.09.
The "IGNCR" bit of the "c_iflag". This ignores incoming CR characters.
icrnl
Since version 0.09.
The "ICRNL" bit of the "c_iflag". This translates CR to NL on input, unless "IGNCR" is also set.
ignbrk
Since version 0.09.
The "IGNBRK" bit of the "c_iflag". This controls whether incoming break conditions are ignored entirely.
brkint
Since version 0.09.
The "BRKINT" bit of the "c_iflag". This controls whether non-ignored incoming break conditions result in
a "SIGINT" signal being delivered to the process. If not, such a condition reads as a nul byte.
parmrk
Since version 0.09.
The "PARMRK" bit of the "c_iflag". This controls how parity errors and break conditions are handled.
opost
Since version 0.07.
The "OPOST" bit of the "c_oflag". This enables system-specific post-processing on output.
cread
The "CREAD" bit of the "c_cflag". This enables the receiver.
hupcl
The "HUPCL" bit of the "c_cflag". This lowers the modem control lines after the last process closes the
device.
clocal
The "CLOCAL" bit of the "c_cflag". This controls whether local mode is enabled; which if set, ignores
modem control lines.
icanon
The "ICANON" bit of "c_lflag". This is called "canonical" mode and controls whether the terminal's line-
editing feature will be used to return a whole line (if true), or if individual bytes from keystrokes
will be returned as they are available (if false).
echo
The "ECHO" bit of "c_lflag". This controls whether input characters are echoed back to the terminal.
setflags
$term->setflags( @flags );
Since version 0.09.
A convenient wrapper to calling multiple flag setting methods in a sequence.
Each flag is specified by name, in lower case, prefixed by either a "+" symbol to enable it, or "-" to
disable. For example:
$term->setflags( "+igncr", "+opost", "+clocal", "-echo" );
TODO
• Adding more getflag_*/setflag_* convenience wrappers
SEE ALSO
• IO::Tty - Import Tty control constants
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>