Originální popis anglicky:
tcgetattr - get the parameters associated with the terminal
Návod, kniha: POSIX Programmer's Manual
#include <termios.h>
int tcgetattr(int
fildes, struct termios
*termios_p);
The
tcgetattr() function shall get the parameters associated with the
terminal referred to by
fildes and store them in the
termios
structure referenced by
termios_p. The
fildes argument is an
open file descriptor associated with a terminal.
The
termios_p argument is a pointer to a
termios structure.
The
tcgetattr() operation is allowed from any process.
If the terminal device supports different input and output baud rates, the baud
rates stored in the
termios structure returned by
tcgetattr()
shall reflect the actual baud rates, even if they are equal. If differing baud
rates are not supported, the rate returned as the output baud rate shall be
the actual baud rate. If the terminal device does not support split baud
rates, the input baud rate stored in the
termios structure shall be the
output rate (as one of the symbolic values).
Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned
and
errno set to indicate the error.
The
tcgetattr() function shall fail if:
- EBADF
- The fildes argument is not a valid file
descriptor.
- ENOTTY
- The file associated with fildes is not a terminal.
The following sections are informative.
None.
None.
Care must be taken when changing the terminal attributes. Applications should
always do a
tcgetattr(), save the
termios structure values
returned, and then do a
tcsetattr(), changing only the necessary
fields. The application should use the values saved from the
tcgetattr() to reset the terminal state whenever it is done with the
terminal. This is necessary because terminal attributes apply to the
underlying port and not to each individual open instance; that is, all
processes that have used the terminal see the latest attribute changes.
A program that uses these functions should be written to catch all signals and
take other appropriate actions to ensure that when the program terminates,
whether planned or not, the terminal device's state is restored to its
original state.
Existing practice dealing with error returns when only part of a request can be
honored is based on calls to the
ioctl() function. In historical BSD
and System V implementations, the corresponding
ioctl() returns zero if
the requested actions were semantically correct, even if some of the requested
changes could not be made. Many existing applications assume this behavior and
would no longer work correctly if the return value were changed from zero to
-1 in this case.
Note that either specification has a problem. When zero is returned, it implies
everything succeeded even if some of the changes were not made. When -1 is
returned, it implies everything failed even though some of the changes were
made.
Applications that need all of the requested changes made to work properly should
follow
tcsetattr() with a call to
tcgetattr() and compare the
appropriate field values.
None.
tcsetattr() , the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface,
<termios.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
