tcgetpgrp()

Updated: May 06, 2022

Get the process group ID associated with a device

Synopsis:

#include <unistd.h>

pid_t tcgetpgrp( int filedes );

Arguments:

filedes
A file descriptor that's associated with the device whose process group ID you want to get.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The tcgetpgrp() function returns the process group ID of the foreground process that's associated with the device indicated by filedes.

If there's no foreground process group, tcgetpgrp() returns a value greater than 1 that doesn't match the process group ID of any existing process group.

You can call tcgetpgrp() from a process that's a member of a background process group, but the information may be subsequently changed by a process that's a member of a foreground process group.

Returns:

The ID of foreground process group. If an error occurs, -1 is returned, and errno is set.

Errors:

EBADF
The argument filedes is invalid.
ENOSYS
The resource manager associated with filedes doesn't support this call.
ENOTTY
The calling process doesn't have a controlling terminal, or the file isn't the controlling terminal.

Examples:

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

int main( void )
  {
    printf( "STDIN directs breaks to pgrp %d\n",
        tcgetpgrp( 0 ) );
    return EXIT_SUCCESS;
  }

Classification:

POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler Yes
Thread Yes