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.
CONFORMING TO
POSIX.1-2001.
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)
Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
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