man3/tcgetpgrp.3

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  23 .TH TCGETPGRP 3 2003-01-28 "POSIX" "Linux Programmer's Manual"
  24 .SH NAME
  25 tcgetpgrp, tcsetpgrp \- get and set terminal foreground process group
  26 .SH SYNOPSIS
  27 .sp
  28 .BR "#include <unistd.h>"
  29 .sp
  30 .BI "pid_t tcgetpgrp(int " fd );
  31 .sp
  32 .BI "int tcsetpgrp(int " fd ", pid_t " pgrp );
  33 .SH DESCRIPTION
  34 The function
  35 .BR tcgetpgrp ()
  36 returns the process group ID of the foreground process group on the
  37 terminal associated to
  38 .IR fd ,
  39 which must be the controlling terminal of the calling process.
  40 .\" The process itself may be a background process.
  41 .LP
  42 The function
  43 .BR tcsetpgrp ()
  44 makes the process group with process group ID \fIpgrp\fP
  45 the foreground process group on the terminal associated to
  46 .IR fd ,
  47 which must be the controlling terminal of the calling process,
  48 and still be associated with its session.
  49 Moreover, \fIpgrp\fP must be a (nonempty) process group belonging to
  50 the same session as the calling process.
  51 .LP
  52 If
  53 .BR tcsetpgrp ()
  54 is called by a member of a background process group in its session,
  55 and the calling process is not blocking or ignoring SIGTTOU,
  56 a SIGTTOU signal is sent to all members of this background process group.
  57 .SH "RETURN VALUE"
  58 When
  59 .I fd
  60 refers to the controlling terminal of the calling process,
  61 the function
  62 .BR tcgetpgrp ()
  63 will return the foreground process group ID of that terminal
  64 if there is one, and some value larger than 1 that is not
  65 presently a process group ID otherwise.
  66 When
  67 .I fd
  68 does not refer to the controlling terminal of the calling process,
  69 \-1 is returned, and
  70 .I errno
  71 is set appropriately.
  72 .LP
  73 When successful,
  74 .BR tcsetpgrp ()
  75 returns 0. Otherwise, it returns \-1, and
  76 .I errno
  77 is set appropriately.
  78 .SH ERRORS
  79 .TP
  80 .B EBADF
  81 .I fd
  82 is not a valid file descriptor.
  83 .TP
  84 .B EINVAL
  85 .I pgrp
  86 has an unsupported value.
  87 .TP
  88 .B ENOTTY
  89 The calling process does not have a controlling terminal, or
  90 it has one but it is not described by
  91 .IR fd ,
  92 or, for
  93 .BR tcsetpgrp (),
  94 this controlling terminal is no longer associated with the session
  95 of the calling process.
  96 .TP
  97 .B EPERM
  98 .I pgrp
  99 has a supported value, but is not the process group ID of a
 100 process in the same session as the calling process.
 101 .SH NOTES
 102 These functions are implemented via the TIOCGPGRP and
 103 TIOCSPGRP ioctls.
 104 .SH HISTORY
 105 These ioctls appeared in 4.2 BSD. The functions are POSIX inventions.
 106 .SH "CONFORMS TO"
 107 POSIX.1
 108 .SH "SEE ALSO"
 109 .BR setpgid (2),
 110 .BR setsid (2)