tcgetpgrp(3)               Library Functions Manual               tcgetpgrp(3)

NAME
       tcgetpgrp, tcsetpgrp - get and set terminal foreground process group

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <unistd.h>

       pid_t tcgetpgrp(int fd);
       int tcsetpgrp(int fd, pid_t pgrp);

DESCRIPTION
       The function tcgetpgrp() returns the process group ID of the foreground
       process group on the terminal associated to fd, which must be the
       controlling terminal of the calling process.

       The function tcsetpgrp() makes the process group with process group ID
       pgrp the foreground process group on the terminal associated to fd,
       which must be the controlling terminal of the calling process, and
       still be associated with its session.  Moreover, pgrp must be a
       (nonempty) process group belonging to the same session as the calling
       process.

       If tcsetpgrp() is called by a member of a background process group in
       its session, and the calling process is not blocking or ignoring
       SIGTTOU, a SIGTTOU signal is sent to all members of this background
       process group.

RETURN VALUE
       When fd refers to the controlling terminal of the calling process, the
       function tcgetpgrp() will return the foreground process group ID of
       that terminal if there is one, and some value larger than 1 that is not
       presently a process group ID otherwise.  When fd does not refer to the
       controlling terminal of the calling process, -1 is returned, and errno
       is set to indicate the error.

       When successful, tcsetpgrp() returns 0.  Otherwise, it returns -1, and
       errno is set to indicate the error.

ERRORS
       EBADF  fd is not a valid file descriptor.

       EINVAL pgrp has an unsupported value.

       ENOTTY The calling process does not have a controlling terminal, or it
              has one but it is not described by fd, or, for tcsetpgrp(), this
              controlling terminal is no longer associated with the session of
              the calling process.

       EPERM  pgrp has a supported value, but is not the process group ID of a
              process in the same session as the calling process.

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |tcgetpgrp (), tcsetpgrp ()                  | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
VERSIONS
       These functions are implemented via the TIOCGPGRP and TIOCSPGRP ioctls.

STANDARDS
       POSIX.1-2008.

HISTORY
       POSIX.1-2001.

       The ioctls appeared in 4.2BSD.  The functions are POSIX inventions.

SEE ALSO
       setpgid(2), setsid(2), credentials(7)

Linux man-pages 6.7               2023-10-31                      tcgetpgrp(3)