Advanced Programming in the UNIX® Environment

ptg10805159

Section 18.3 Special Input Characters 681

ERASE2 The alternate erase character (backspace). This character is treated exactly

like the erase character(ERASE).

INTR The interrupt character.This character is recognized on input if theISIG

flag is set and generates theSIGINTsignal that is sent to all processes in

the foreground process group (refer to Figure9.7). This character is

discarded when processed (i.e., it is not passed to the process).

KILL The kill character.(The name ‘‘kill’’ is overused; recall thekillfunction

used to send a signal to a process. This character should be called the

line-erase character; it has nothing to do with signals.) It is recognized on

input in canonical mode (ICANON). It erases the entireline and is discarded

when processed (i.e., it is not passed to the process).

LNEXT The literal-next character.This character is recognized on input in extended

mode (IEXTEN)and causes any special meaning of the next character to be

ignored. This works for all special characters listed in this section.We can

use this character to type any character to a program. The LNEXT character

is discarded when processed, but the next character entered is passed to the

process.

NL The newline character,also called the line delimiter.Wecannot change this

character.It is recognized on input in canonical mode (ICANON). This

character is returned to the reading process.

QUIT The quit character.This character is recognized on input if theISIGflag is

set. The quit character generates theSIGQUITsignal, which is sent to all

processes in the foreground process group (refer to Figure9.7). This

character is discarded when processed (i.e., it is not passed to the process).

Recall from Figure10.1 that the difference between INTR and QUIT is that

the QUIT character not only terminates the process by default, but also

generates acorefile.

REPRINT Thereprint character.This character is recognized on input in extended,

canonical mode (bothIEXTENandICANONflags set) and causes all unread

input to be output (reechoed). This character is discarded when processed

(i.e., it is not passed to the process).

STARTThe start character.This character is recognized on input if theIXONflag is

set and is automatically generated as output if theIXOFFflag is set. A

received STARTcharacter withIXONset causes stopped output (from a

previously entered STOP character) to restart. In this case, the START

character is discarded when processed (i.e., it is not passed to the process).

WhenIXOFFis set, the terminal driver automatically generates a START

character to resume input that it had previously stopped, when the new

input will not overflow the input buffer.