TCSETS(2const) TCSETS(2const)
NAME
TCGETS, TCSETS, TCSETSW, TCSETSF, TCGETS2, TCSETS2, TCSETSW2, TCSETSF2,
TCGETA, TCSETA, TCSETAW, TCSETAF - get and set terminal attributes
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <asm/termbits.h> /* Definition of TC* constants */
#include <sys/ioctl.h>
int ioctl(int fd, TCGETS, struct termios *argp);
int ioctl(int fd, TCSETS, const struct termios *argp);
int ioctl(int fd, TCSETSW, const struct termios *argp);
int ioctl(int fd, TCSETSF, const struct termios *argp);
int ioctl(int fd, TCGETS2, struct termios2 *argp);
int ioctl(int fd, TCSETS2, const struct termios2 *argp);
int ioctl(int fd, TCSETSW2, const struct termios2 *argp);
int ioctl(int fd, TCSETSF2, const struct termios2 *argp);
int ioctl(int fd, TCGETA, struct termio *argp);
int ioctl(int fd, TCSETA, const struct termio *argp);
int ioctl(int fd, TCSETAW, const struct termio *argp);
int ioctl(int fd, TCSETAF, const struct termio *argp);
#include <asm/termbits.h>
struct termios;
struct termios2;
struct termio;
DESCRIPTION
TCGETS Equivalent to tcgetattr(fd, argp).
Get the current serial port settings.
TCSETS Equivalent to tcsetattr(fd, TCSANOW, argp).
Set the current serial port settings.
TCSETSW
Equivalent to tcsetattr(fd, TCSADRAIN, argp).
Allow the output buffer to drain, and set the current serial port
settings.
TCSETSF
Equivalent to tcsetattr(fd, TCSAFLUSH, argp).
Allow the output buffer to drain, discard pending input, and set
the current serial port settings.
The following four ioctls are just like TCGETS, TCSETS, TCSETSW, TC-
SETSF, except that they take a struct termios2 * instead of a struct
termios *. If the structure member c_cflag contains the flag BOTHER,
then the baud rate is stored in the structure members c_ispeed and c_os-
peed as integer values. These ioctls are not supported on all architec-
tures.
TCGETS2
TCSETS2
TCSETSW2
TCSETSF2
The following four ioctls are just like TCGETS, TCSETS, TCSETSW, TC-
SETSF, except that they take a struct termio * instead of a struct
termios *.
TCGETA
TCSETA
TCSETAW
TCSETAF
RETURN VALUE
On success, 0 is returned. On error, -1 is returned and errno is set to
indicate the error.
ERRORS
EPERM Insufficient permission.
HISTORY
TCGETS2
TCSETS2
TCSETSW2
TCSETSF2
Linux 2.6.20.
CAVEATS
struct termios from <asm/termbits.h> is different and incompatible with
struct termios from <termios.h>. These ioctl calls require struct
termios from <asm/termbits.h>.
EXAMPLES
Get or set arbitrary baudrate on the serial port.
/* SPDX-License-Identifier: GPL-2.0-or-later */
#include <asm/termbits.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
#if !defined BOTHER
fprintf(stderr, "BOTHER is unsupported\n");
/* Program may fallback to TCGETS/TCSETS with Bnnn constants */
exit(EXIT_FAILURE);
#else
/* Declare tio structure, its type depends on supported ioctl */
# if defined TCGETS2
struct termios2 tio;
# else
struct termios tio;
# endif
int fd, rc;
if (argc != 2 && argc != 3 && argc != 4) {
fprintf(stderr, "Usage: %s device [output [input] ]\n", argv[0]);
exit(EXIT_FAILURE);
}
fd = open(argv[1], O_RDWR | O_NONBLOCK | O_NOCTTY);
if (fd < 0) {
perror("open");
exit(EXIT_FAILURE);
}
/* Get the current serial port settings via supported ioctl */
# if defined TCGETS2
rc = ioctl(fd, TCGETS2, &tio);
# else
rc = ioctl(fd, TCGETS, &tio);
# endif
if (rc) {
perror("TCGETS");
close(fd);
exit(EXIT_FAILURE);
}
/* Change baud rate when more arguments were provided */
if (argc == 3 || argc == 4) {
/* Clear the current output baud rate and fill a new value */
tio.c_cflag &= ~CBAUD;
tio.c_cflag |= BOTHER;
tio.c_ospeed = atoi(argv[2]);
/* Clear the current input baud rate and fill a new value */
tio.c_cflag &= ~(CBAUD << IBSHIFT);
tio.c_cflag |= BOTHER << IBSHIFT;
/* When 4th argument is not provided reuse output baud rate */
tio.c_ispeed = (argc == 4) ? atoi(argv[3]) : atoi(argv[2]);
/* Set new serial port settings via supported ioctl */
# if defined TCSETS2
rc = ioctl(fd, TCSETS2, &tio);
# else
rc = ioctl(fd, TCSETS, &tio);
# endif
if (rc) {
perror("TCSETS");
close(fd);
exit(EXIT_FAILURE);
}
/* And get new values which were really configured */
# if defined TCGETS2
rc = ioctl(fd, TCGETS2, &tio);
# else
rc = ioctl(fd, TCGETS, &tio);
# endif
if (rc) {
perror("TCGETS");
close(fd);
exit(EXIT_FAILURE);
}
}
close(fd);
printf("output baud rate: %u\n", tio.c_ospeed);
printf("input baud rate: %u\n", tio.c_ispeed);
exit(EXIT_SUCCESS);
#endif
}
SEE ALSO
ioctl(2), ioctl_tty(2), termios(3)
Linux man-pages 6.9.1 2024-06-15 TCSETS(2const)
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