Before starting to output commands to a terminal using termcap, an application program should do two things:
ospeedfor padding (see section Performing Padding with
BCfor cursor motion (see section
To turn off output processing in Berkeley Unix you would use
TIOCLSET to set the bit named
LLITOUT, and clear
TIOCSETN. In POSIX or System V, you
must clear the bit named
OPOST. Refer to the system documentation
If you do not set the terminal flags properly, some older terminals will not work. This is because their commands may contain the characters that normally signify newline, carriage return and horizontal tab--characters which the kernel thinks it ought to modify before output.
When you change the kernel's terminal flags, you must arrange to restore
them to their normal state when your program exits. This implies that the
program must catch fatal signals such as
and restore the old terminal flags before actually terminating.
Modern terminals' commands do not use these special characters, so if you do not care about problems with old terminals, you can leave the kernel's terminal flags unaltered.
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