tcgetpgrp Subroutine
Purpose
Gets foreground process group ID.
Library
Standard C Library (libc.a)
Syntax
#include <unistd.h>pid_t tcgetpgrp ( FileDescriptor)
int FileDescriptor;
int FileDescriptor;
Description
The tcgetpgrp subroutine returns the value of the process group ID of the foreground process group associated with the terminal. The function can be called from a background process; however, the foreground process can subsequently change the information.
Parameters
| Item | Description |
|---|---|
| FileDescriptor | Indicates the open file descriptor for the terminal special file. |
Return Values
Upon successful completion, the process group ID of the foreground process is returned. If there is no foreground process group, a value greater than 1 that does not match the process group ID of any existing process group is returned. Otherwise, a value of -1 is returned and the errno global variable is set to indicate the error.
Error Codes
The tcgetpgrp subroutine is unsuccessful if one of the following is true:
| Item | Description |
|---|---|
| EBADF | The FileDescriptor argument is not a valid file descriptor. |
| EINVAL | The function is not appropriate for the file associated with the FileDescriptor argument. |
| ENOTTY | The calling process does not have a controlling terminal or the file is not the controlling terminal. |