cfgetospeed() — Determine the output baud rate

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>

speed_t cfgetospeed(const struct termios *termptr);

General description

Extracts the output baud rate from the termios structure indicated by *termptr. The termios structure contains information about a terminal. A program should first use tcgetattr() to get the termios structure, and then use cfgetospeed() to extract the speed from the structure. The program can then use cfgetospeed() to set a new baud rate in the structure and tcsetattr() to pass the changed value to the system.

Although in a z/OS® UNIX application valid speeds can be set with cfsetospeed() and passed to the system with tcsetattr(), the speed has no effect on the operation a pseudoterminal. However, the operation will have an effect if issued for an OCS remote terminal.

Returned value

cfgetospeed() returns a code indicating the baud rate. The codes are defined in the termios.h header file and have an unsigned integer type. Table 1 shows the codes to set the baud rate.

There are no documented errno values.

Example

CELEBC06

⁄* CELEBC06

   This example determines the speed of stdout.

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

char *see_speed(speed_t speed) {
  static char   SPEED[20];
  switch (speed) {
    case B0:       strcpy(SPEED, "B0");
                   break;
    case B50:      strcpy(SPEED, "B50");
                   break;
    case B75:      strcpy(SPEED, "B75");
                   break;
    case B110:     strcpy(SPEED, "B110");
                   break;
    case B134:     strcpy(SPEED, "B134");
                   break;
    case B150:     strcpy(SPEED, "B150");
                   break;
    case B200:     strcpy(SPEED, "B200");
                   break;
    case B300:     strcpy(SPEED, "B300");
                   break;
    case B600:     strcpy(SPEED, "B600");
                   break;
    case B1200:    strcpy(SPEED, "B1200");
                   break;
    case B1800:    strcpy(SPEED, "B1800");
                   break;
    case B2400:    strcpy(SPEED, "B2400");
                   break;
    case B4800:    strcpy(SPEED, "B4800");
                   break;
    case B9600:    strcpy(SPEED, "B9600");
                   break;
    case B19200:   strcpy(SPEED, "B19200");
                   break;
    case B38400:   strcpy(SPEED, "B38400");
                   break;
    default:       sprintf(SPEED, "unknown (%d)", (int) speed);
  }
  return SPEED;
}

main() {
  struct termios term;
  speed_t speed;

  if (tcgetattr(1, &term) != 0)
    perror("tcgetattr() error");
  else {
    speed = cfgetospeed(&term);
    printf("cfgetospeed() says the speed of stdout is %s\n",
           see_speed(speed));
  }
}

Output

cfgetospeed() says the speed of stdout is B0