#include <sys/types.h> #include <unistd.h> int tcsetpgrp(int fildes, pid_t pgid_id);
If the process has a controlling terminal, tcsetpgrp() will set the foreground process group ID associated with the terminal to pgid_id. The file associated with fildes must be the controlling terminal of the calling process and the controlling terminal must be currently associated with the session of the calling process. The value of pgid_id must match a process group ID of a process in the same session as the calling process.
Upon successful completion, 0 is returned. Otherwise, −1 is returned and errno is set to indicate the error.
The tcsetpgrp() function will fail if:
The fildes argument is not a valid file descriptor.
This implementation does not support the value in the pgid_id argument.
The calling process does not have a controlling terminal, or the file is not the controlling terminal, or the controlling terminal is no longer associated with the session of the calling process.
The process is not ignoring or holding SIGTTOU and is a member of an orphaned process group.
The value of pgid_id does not match the process group ID of a process in the same session as the calling process.
See attributes(5) for descriptions of the following attributes: