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TCGETPGRP(3) Linux Programmer's Manual TCGETPGRP(3)
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 con‐
trolling terminal of the calling process, and still be associated with its session. Moreover, pgrp must be a (nonempty) process group belonging to the same ses‐
sion 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 │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘
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)
GNU 2021-03-22 TCGETPGRP(3)