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Files Reference
Provides the terminal interface for the Berkeley line discipline.
The sgtty.h file defines the structures used by ioctl
subroutines that apply to terminal files. The structures, definitions,
and values in this file are provided for compatibility with the Berkeley user
interface for asynchronous communication. Window and terminal size
operations use the winsize structure, which is defined in the
ioctl.h file. The winsize structure and
the ioctl functions that use it are described in tty
Subsystem Overview in AIX 5L Version 5.1 General Programming
Concepts: Writing and Debugging Programs.
Note: Version 4 supports the Berkeley line discipline for
compatibility with older applications. However, it is strongly
recommended to use the POSIX compliant line discipline, which interface is
described in the termios.h
file.
Basic ioctl functions use the sgttyb structure defined in the
sgtty.h file. This structure contains the following
fields:
- sg_ispeed
- Specifies the input speed of the device. For any particular
hardware, impossible speed changes are ignored. Symbolic values in the
table are as defined in the sgtty.h file.
- B0
- Hangs up. The zero baud rate is used to hang up the
connection. If B0 is specified, the `data terminal ready' signal
is dropped. As a result, the line is usually disconnected.
- B50
- 50 baud.
- B75
- 75 baud.
- B110
- 110 baud.
- B134
- 134.5 baud.
- B150
- 150 baud.
- B200
- 200 baud.
- B300
- 300 baud.
- B600
- 600 baud.
- B1200
- 1200 baud.
- B1800
- 1800 baud.
- B2400
- 2400 baud.
- B4800
- 4800 baud.
- B9600
- 9600 baud.
- EXTA
- External A.
- EXTB
- External B.
-
-
- sg_ospeed
- Specifies the output speed of the device. Refer to the description
of the sg_ispeed field. The sg_ospeed field has
the same values as the sg_ispeed field.
- sg_erase
- Specifies the erase character. (The default is Backspace.)
- sg_kill
- Specifies the kill character. (The default is Ctrl-U.)
- sg_flags
- Specifies how the system treats output. The initial output-control
value is all bits clear. The possible output modes are:
- ALLDELAY
- Delays algorithm selection.
- BSDELAY
- Selects backspace delays. Backspace delays are currently
ignored. Possible values are BS0 or BS1.
- VTDELAY
- Selects form-feed and vertical-tab delays:
- FF0
- Specifies no delay.
- FF1
- Specifies one delay of approximately 2 seconds.
-
-
- CRDELAY
- Selects carriage-return delays:
- CR0
- Specifies no delay.
- CR1
- Specifies one delay. The delay lasts approximately 0.08
seconds.
- CR2
- Specifies one delay. The delay lasts approximately 0.16
seconds.
- CR3
- Specifies one delay. The delay pads lines to be at least 9
characters at 9600 baud.
-
-
- TBDELAY
- Selects tab delays:
- TAB0
- Specifies no delay.
- TAB1
- Specifies one delay. The delay is dependent on the amount of
movement.
- TAB2
- Specifies one delay. The delay lasts about 0.10
seconds.
- XTABS
- Specifies that tabs are to be replaced by the appropriate number of spaces
on output.
-
-
- NLDELAY
- Selects the new-line character delays. This is a mask to use before
comparing to NL0 and NL1.
- NL0
- Specifies no delay.
- NL1
- Specifies one delay. The delay is dependent on the current
column.
- NL2
- Specifies one delay. The delay lasts about 0.10
seconds.
The delay bits specify how long
transmission stops to allow for mechanical or other movement when certain
characters are sent to the terminal. The actual delays depend on line
speed and system load.
-
-
- EVENP
- Allows even parity on input.
The EVENP and
ODDP flags control both parity checking on input and parity
generation on output in COOKED and CBREAK mode (unless the LPASS8 bit is
enabled). Even parity is generated on output unless the ODDP
flag is set and the EVENP flag is clear, in which case odd parity
is generated. Input characters with the wrong parity, as determined by
the EVENP and ODDP flags, are ignored in COOKED and
CBREAK mode.
- ODDP
- Allows odd parity on input. Refer to the description of the
EVENP flag.
- RAW
- Indicates the RAW mode, which features a wake up on all characters and an
8-bit interface.
The RAW mode disables all processing
except output flushing specified by the LFLUSHO bit. The
full 8 bits of input are given as soon as they are available; all 8 bits
are passed on output. A break condition in the input is reported as a
null character. If the input queue overflows in RAW mode, all data in
the input and output queues is discarded; this applies to both the new
and old drivers.
- CRMOD
- Maps a carriage return into a new line on input and outputs a new line as
a carriage return and a new line.
- ECHO
- Echo (full duplex).
- LCASE
- Maps uppercase to lowercase on input and lowercase to uppercase on output
on uppercase terminals.
- CBREAK
- Enables a half-cooked mode. Programs can read each character as it
is typed instead of waiting for a full line. All processing is done
except input editing. Character and word erase, line kill, input
reprint, and special treatment of the backslash character and the EOT
character are disabled.
- TANDEM
- Enables automatic flow control (TANDEM mode), which causes the system to
produce a stop character (Ctrl-S) when the input queue is in danger of
overflowing, and a start character (Ctrl-Q) when the input queue has drained
sufficiently. This mode is useful for flow control when the terminal is
actually another computer that understands the conventions.
Note: The same
stop and start characters are used for both directions of flow control.
The character specified by the t_stopc field is accepted on input
as the character that stops output and is produced on output as the character
to stop input. The character specified by the t_startc field
is accepted on input as the character that restarts output and is produced on
output as the character to restart input.
-
-
A large number of ioctl commands
apply to terminals. Some have the general form:
#include <sgtty.h>
ioctl(FileDescriptor, Code, Value)
struct sgttyb *Value;
The applicable values for the
Code parameter are:
| TIOCGETP
| Fetches the basic parameters associated with the terminal and stores them
in the sgttyb structure that is pointed to.
|
| TIOCSETP
| Sets the parameters according to the sgttyb structure that is
pointed to. The interface delays until output stops, then throws away
any unread characters before changing the modes.
|
| TIOCSETN
| Has the same effect as the TIOCSETP value but does not delay
or flush input. Input is not preserved, however, when changing to or
from the RAW mode.
|
For the following codes, the
Value parameter is ignored:
| TIOCEXCL
| Sets exclusive-use mode; no further opens are permitted until the
file is closed.
|
| TIOCNXCL
| Turns off exclusive-use mode.
|
| TIOCHPCL
| When the file is closed for the last time, hangs up the terminal.
This is useful when the line is associated with a modem used to place outgoing
calls.
|
For the following code, the
Value parameter is a pointer to an integer.
| TIOCFLUSH
| If the integer pointed to by the Value parameter has a zero
value, all characters waiting in input or output queues are flushed.
Otherwise, the value of the integer applies to the FREAD and FWRITE bits
defined in the fcntl.h file. If the FREAD bit is set,
all characters waiting in input queues are flushed. If the FWRITE bit
is set, all characters waiting in output queues are flushed.
Note: The FREAD and FWRITE bits cannot be used unless
the _KERNEL flag is set.
|
In the following codes, the
argument is 0 unless specified otherwise:
| TIOCSTI
| The Value parameter points to a character that the system
pretends has been typed on the terminal.
|
| TIOCSBRK
| The break bit is set in the terminal.
|
| TIOCCBRK
| The break bit is cleared.
|
| TIOCSDTR
| Data terminal ready is set.
|
| TIOCCDTR
| Data terminal ready is cleared.
|
| TIOCSTOP
| Output is stopped as if the stop character had been typed.
|
| TIOCSTART
| Output is restarted as if the start character had been typed.
|
| TIOCGPGRP
| The Value parameter is a pointer to an integer into which is
placed the process group ID of the process group for which this terminal is
the control terminal.
|
| TIOCSPGRP
| The Value parameter is a pointer to an integer which is the
value to which the process group ID for this terminal will be set.
|
| TIOCOUTQ
| Returns in the integer pointed to by the Value parameter the
number of characters queued for output to the terminal.
|
| TIONREAD
| Returns in the integer pointed to by the Value parameter the
number of characters immediately readable from the argument descriptor.
This works for files, pipes, and terminals.
|
If the LCASE
output-mode bit is set, all uppercase letters are mapped into the
corresponding lowercase letter. The uppercase letter can be generated
by preceding it with a \ (backslash). Uppercase letters are preceded by
a backslash when they are output. In addition, the following escape
sequences can be generated on output and accepted on input:
| For
| Use
|
| ` (grave)
| \'
|
| |
| \!
|
| ~
| \^
|
| {
| \(
|
| }
| \)
|
To deal with terminals that do
not understand that the ~ (tilde) has been made into an ASCII character, the
LTILDE bit can be set in the local-mode word. When the
LTILDE bit is set, the ~ (tilde) character will be replaced with
the ` (grave) character on output.
A tchars structure
associated with each terminal specifies special characters for both the old
and new terminal interfaces. This structure is defined in the
ioctl.h file, for which the sgtty.h file
contains an #include statement. The tchars
structure contains the following fields:
| t_intrc
| The interrupt character (Ctrl-C, by default) generates a
SIGINT signal. This is the normal way to stop a process that
is no longer needed or to regain control in an interactive program.
|
| t_quitc
| The quit character (Ctrl-\, by default) generates a SIGQUIT
signal. This is used to end a program and produce a core image, if
possible, in a core file in the current directory.
|
| t_startc
| The start-output character (Ctrl-Q, by default).
|
| t_stopc
| The stop-output character (Ctrl-S, by default).
|
| t_eofc
| The end-of-file character (Ctrl-D, by default).
|
| t_brkc
| The input delimiter (-1, by default). This character acts like a
newline in that it ends a line, is echoed, and is passed to the
program.
|
The stop and start characters can
be the same to produce a toggle effect. The applicable ioctl functions
are:
| TIOCGETC
| Gets the special characters and puts them in the specified
structure.
|
| TIOCSETC
| Sets the special characters to those given in the structure.
|
Associated with each terminal is
a local-mode word. The bits of the local-mode word are:
| LCRTBS
| Backspaces on erase rather than echoing erase.
|
| LPRTERA
| Printing terminal erase mode.
|
| LCRTERA
| Erases character echoes as Backspace-Space-Backspace.
|
| LTILDE
| Converts ~ (tilde) to ` (grave) on output (for terminals that do not
recognize the tilde as an ASCII character).
|
| LMDMBUF
| Stops and starts output when carrier drops.
|
| LLITOUT
| Suppresses output translations.
|
| LTOSTOP
| Sends a SIGTTOU signal for background output.
|
| LFLUSHO
| Output is being flushed.
|
| LNOHANG
| Do not send hang up when carrier drops.
|
| LCRTKIL
| Backspace-Space-Backspace to erase the entire line on line kill.
|
| LPASS8
| Passes all 8 bits through on input, in any mode.
|
| LCTLECH
| Echoes input control characters as Ctrl-X, delete as
Ctrl-?.
|
| LPENDIN
| Retypes pending input at next read or input character.
|
| LDECCTQ
| Only Ctrl-Q restarts output after a Ctrl-S.
|
| LNOFLSH
| Inhibits flushing of pending I/O when an interrupt character is
typed.
|
The following ioctl functions
operate on the local-mode word structure:
| TIOCLBIS
| The Value parameter is a pointer to an integer whose value is
a mask containing the bits to be set in the local-mode word.
|
| TIOCLBIC
| The Value parameter is a pointer to an integer whose value is
a mask containing the bits to be cleared in the local-mode word.
|
| TIOCLSET
| The Value parameter is a pointer to an integer whose value is
stored in the local-mode word.
|
| TIOCLGET
| The Value parameter is a pointer to an integer into which the
current local-mode word is placed.
|
The ltchars structure
associated with each terminal defines control characters for the new terminal
driver. This structure contains the following fields:
| t_suspc
| The suspend-process character (Ctrl-Z, by default). This sends a
SIGTSTP signal to suspend the current process group. This
character is recognized during input.
|
| t_dsuspc
| The delayed suspend-process character (Ctrl-Y, by default). This
sends a SIGTSTP signal to suspend the current process group.
This character is recognized when the process attempts to read the control
character rather than when the character is typed.
|
| t_rprntc
| The reprint line-control character (Ctrl-R, by default). This
reprints all characters that are preceded by a new-line character and have not
been read.
|
| t_flushc
| The flush-output character (Ctrl-O, by default). This flushes data
that is written but not transmitted.
|
| t_werasc
| The word-erase character (Ctrl-W, by default). This erases the
preceding word. This does not erase beyond the beginning of the
line.
|
| t_lnextc
| The literal-next character (Ctrl-V, by default). This causes the
special meaning of the next character to be ignored so that characters can be
input without being interpreted by the system.
|
The following ioctl functions,
which use the ltchars structure, are supported by the terminal
interface for the definition of local special characters for a terminal:
| TIOCSLTC
| Sets local characters. The argument to this function is a pointer
to an ltchars structure, which defines the new local special
characters.
|
| TIOCGLTC
| Sets local characters. The argument to this function is a pointer
to an ltchars structure into which is placed the current set of
local special characters.
|
The winsize structure
and the ioctl functions that use it are described in the discussion of the tty
common code in "tty Subsystem Overview" in AIX 5L
Version 5.1 General Programming Concepts: Writing and Debugging
Programs.
This file is for Berkeley
compatibility.
This file is part of Base
Operating System (BOS) Runtime.
| /dev/tty
| The tty special file, which is a synonym for the controlling
terminal.
|
The csh command, getty command, stty command, tset command.
The ioctl subroutine, sigvec subroutine.
tty Subsystem
Overview in AIX 5L Version 5.1 General Programming
Concepts: Writing and Debugging Programs.
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Library Home |
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