.sp
.SH DESCRIPTION
The
-.IR ioctl ()
+.BR ioctl ()
call for terminals and serial ports accepts many possible command arguments.
Most require a third argument, of varying type, here called \fIargp\fP
or \fIarg\fP.
.SH "RETURN VALUE"
The
-.IR ioctl ()
+.BR ioctl ()
system call returns 0 on success. On error it returns \-1 and sets
.I errno
appropriately.