NAME

       tcgetpgrp, tcsetpgrp - get and set terminal foreground process group

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 appropriately.

       When successful, tcsetpgrp() returns 0.  Otherwise, it returns -1, and errno is set appropriately.

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 │
       └─────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008.

NOTES

       These functions are implemented via the TIOCGPGRP and TIOCSPGRP ioctls.

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

SEE ALSO

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

COLOPHON

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