tcgetpgrp(3) — Linux manual page

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)

COLOPHON

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

Pages that refer to this page: setpgid(2), TIOCSPGRP(2const), credentials(7), signal-safety(7)

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