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  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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