tcsendbreak() — Send a break condition to a terminal

Standards

Standards / Extensions	C or C++	Dependencies
POSIX.1 XPG4 XPG4.2 Single UNIX Specification, Version 3	both

Format

#define _POSIX_SOURCE
#include <termios.h>

int tcsendbreak(int fildes, int duration);

General description

Sends a break condition to a terminal (indicated by fildes) that is using asynchronous serial data transmission. tcsendbreak() sends a continuous stream of zero bits for the specified duration. tcsendbreak() is the usual method of sending a BREAK on a line.

If tcsendbreak() is issued against a pseudoterminal, this function has no effect.

If tcsendbreak() is called from a background process group against the caller's controlling terminal, a SIGTTOU signal may be generated depending how the process is handling SIGTTOUs:

Processing for SIGTTOU	System Behavior
Default or signal handler	The SIGTTOU signal is generated, and the function is not performed. tcsendbreak() returns -1 and sets errno to EINTR.
Ignored or blocked	The SIGTTOU signal is not sent, and the function continues normally.

Returned value

If successful, tcsendbreak() returns 0.

If unsuccessful, tcsendbreak() returns -1 and sets errno to one of the following values:

Error Code: Description
EBADF: fildes is not a valid open file descriptor.
EINTR: A signal interrupted tcsendbreak().
EIO: The process group of the process issuing the function is an orphaned, background process group, and the process issuing the function is not ignoring or blocking SIGTTOU.
ENOTTY: fildes is not associated with a terminal.

Example

CELEBT08

⁄* CELEBT08

   This example breaks terminal transmission.

 *⁄
#define _POSIX_SOURCE
#include <stdio.h>
#include <termios.h>
#include <unistd.h>

main() {
  if (tcsendbreak(STDIN_FILENO, 100) != 0)
    perror("tcsendbreak() error");
  else
    puts("break sent");
}