tcgetpgrp, tcsetpgrp - get and set terminal foreground process group

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ tcgetpgrp(), tcsetpgrp()                                                    │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       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.

EBADFfd is not a valid file descriptor.

       EINVALpgrp 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.

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

       POSIX.1-2001.

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

       Standard C library (libc, -lc)

       tcgetpgrp, tcsetpgrp - get and set terminal foreground process group

       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.

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

Linux man-pages 6.9.1                              2024-05-02                                       tcgetpgrp(3)

       POSIX.1-2008.

#include<unistd.h>pid_ttcgetpgrp(intfd);inttcsetpgrp(intfd,pid_tpgrp);

       These functions are implemented via the TIOCGPGRP and TIOCSPGRP ioctls.