Clear keyboard input buffer in Bourne shell

Prev		Next

Newsgroups: comp.unix.shell

>extraneous characters are generated -- and they end up in the keyboard's
>input buffer, so that the next prompt the user sees has these characters
>present (though ...

I'll stick to some generic advice on the subject:

Some systems have a stty command which supports a "flushi" and/or a "flush" option, in which case you can use that.

Otherwise you probably will need to resort to compiling this "flushi" program:

#include <unistd.h>
#include <termios.h>
int main(void) { tcflush(STDIN_FILENO, TCIFLUSH); return 0; }

Some other, more kludgy solutions:

make use of the escape sequence which pushes characters into the input buffer to push some known string, perhaps "FLUSH!!!", followed by a newline. Put a read loop in your script which exits when it sees a line which ends with this string.

if job control (SIGTTIN) doesn't get in the way:

s=`stty -g`; stty -echo raw
cat >/dev/null & sleep 3; kill $?
stty $s

(where the "3" is some arbritrary delay, long enough to be
confident that all pending input has been read (with a high
degree of probability), short enough to not be overly annoying)

Ken Pizzini