termios.html

unix 下的C开发手册,还用详细的例程。

<h4><a name = "tag_008_002_001">&nbsp;</a>The termios Structure</h4>
Routines that need to control certain
terminal I/O characteristics do so by using the
<b>termios</b> structure as defined in the header
<i><a href="../xsh/termios.h.html">&lt;termios.h&gt;</a></i>.
The members of this structure include (but are not limited to):
<pre>
<table  bordercolor=#000000 border=1 align=center><tr valign=top><th align=center><b>Member Type</b>
<th align=center><b>Array Size</b>
<th align=center><b>Member Name</b>
<th align=center><b>Description</b>
<tr valign=top><td align=left>tcflag_t
<td align=left>&nbsp;
<td align=left>c_iflag
<td align=left>Input modes.
<tr valign=top><td align=left>tcflag_t
<td align=left>&nbsp;
<td align=left>c_oflag
<td align=left>Output modes.
<tr valign=top><td align=left>tcflag_t
<td align=left>&nbsp;
<td align=left>c_cflag
<td align=left>Control modes.
<tr valign=top><td align=left>tcflag_t
<td align=left>&nbsp;
<td align=left>c_lflag
<td align=left>Local modes.
<tr valign=top><td align=left>cc_t
<td align=left>NCCS
<td align=left>c_cc[]
<td align=left>Control characters.
</table>
</pre>
<p>
The types
<b>tcflag_t</b>
and
<b>cc_t</b>
are defined in the header
<i><a href="../xsh/termios.h.html">&lt;termios.h&gt;</a></i>.
They are
unsigned integral types.
<h4><a name = "tag_008_002_002">&nbsp;</a>Input Modes</h4>
<xref type="3" name="inmodes"></xref>
Values of the
<b>c_iflag</b>
field describe the basic
terminal input control, and are composed of the
bitwise inclusive OR of the masks shown, which will be
bitwise distinct.
The mask name symbols in this table are defined in
<i><a href="../xsh/termios.h.html">&lt;termios.h&gt;</a></i>:
<p><table  bordercolor=#000000 border=1 align=center><tr valign=top><th align=center><b>Mask Name</b>
<th align=center><b>Description</b>
<tr valign=top><td align=left>BRKINT
<td align=left>Signal interrupt on break.
<tr valign=top><td align=left>ICRNL
<td align=left>Map CR to NL on input.
<tr valign=top><td align=left>IGNBRK
<td align=left>Ignore break condition.
<tr valign=top><td align=left>IGNCR
<td align=left>Ignore CR.
<tr valign=top><td align=left>IGNPAR
<td align=left>Ignore characters with parity errors.
<tr valign=top><td align=left>INLCR
<td align=left>Map NL to CR on input.
<tr valign=top><td align=left>INPCK
<td align=left>Enable input parity check.
<tr valign=top><td align=left>ISTRIP
<td align=left>Strip character.
<tr valign=top><td align=left>IUCLC
<td align=left>Map upper case to lower case on input. (<b>LEGACY</b>)  
<tr valign=top><td align=left>IXANY
<td align=left>Enable any character to restart output.  
<tr valign=top><td align=left>IXOFF
<td align=left>Enable start/stop input control.
<tr valign=top><td align=left>IXON
<td align=left>Enable start/stop output control.
<tr valign=top><td align=left>PARMRK
<td align=left>Mark parity errors.
</table>
<p>
In the context of asynchronous serial
data transmission, a break condition is defined as a
sequence of zero-valued bits that continues
for more than the time to send one byte.
The
entire sequence of zero-valued bits is
interpreted as a single break condition, even if it
continues for a time equivalent to
more than one byte.
In contexts other than
asynchronous serial data transmission, the definition
of a break condition is
implementation-dependent.
<p>
If IGNBRK is set, a break condition detected on input is ignored that
is, not put on the input queue and therefore not read by any process.
If IGNBRK is not set and BRKINT is set, the break condition will
flush the input and output queues, and if the terminal is the
controlling terminal of a foreground process group, the break
condition will generate a single SIGINT signal to that foreground
process group.
If neither IGNBRK nor BRKINT is set, a break condition
is read as a single
0x00, or if PARMRK is set,
as 0xff 0x00 0x00.
<p>
If IGNPAR is set, a byte
with a framing or parity error (other than break) is ignored.
<p>
If PARMRK is set,
and IGNPAR is not set, a byte with a framing or parity error (other
than break) is given to the
application as the three-byte sequence
0xff 0x00 X,
where 0xff 0x00 is a two-byte
flag preceding each sequence and X is the data of
the byte received in error.
To avoid ambiguity in this case, if ISTRIP is not set, a
valid byte of 0xff is given
to the application as 0xff 0xff.
If neither
PARMRK nor IGNPAR is set, a
framing or parity error (other than break) is given to the
application as a single byte 0x00.
<p>
If INPCK is set, input parity
checking is enabled.
If INPCK is not set, input parity
checking is disabled, allowing output parity
generation without input parity errors.
Note
that whether input parity checking is
enabled or disabled is independent of whether parity
detection is enabled or disabled (see
<xref href=conmodes><a href="#tag_008_002_004">
Control Modes
</a></xref>).
If parity detection is
enabled but input parity checking is
disabled, the hardware to which the terminal is
connected will recognise the parity bit
but the terminal special file will not check
whether or not this bit is correctly set.
<p>
If ISTRIP is set, valid input
bytes are first stripped to seven bits, otherwise all eight bits
are processed.
<p>
If INLCR is set, a received
NL character is translated into a CR
character.
If IGNCR is set,
a received CR character is ignored
(not read).
If IGNCR is not set and ICRNL is set, a
received CR character is translated into
an NL character.
<p>
If IUCLC is set,
upper- to lower-case mappings are performed
on the received character.
In locales other than the POSIX locale,
the mapping is unspecified. (<b>LEGACY</b>)
<p>
If IXANY is set, any input character will restart output
that has been suspended.
<p>
If IXON is set, start/stop output control is enabled.
A received STOP character suspends output and a received START
character restarts output.
When IXON is set, START and STOP characters are not
read, but merely perform flow control functions.
When IXON is not set, the START and STOP characters are read.
<p>
If IXOFF is set, start/stop input
control is enabled.
The system transmits STOP
characters, which are intended to cause
the terminal device to stop transmitting data, as
needed to prevent the
input queue from
overflowing and causing undefined behaviour,
and transmits START characters,
which are intended to cause the
terminal device to resume transmitting data,
as soon as the device can continue
transmitting data without risk of overflowing
the input queue.
The precise conditions
under which STOP and START characters
are transmitted are implementation-dependent.
<p>
The initial input control value after
<i><a href="../xsh/open.html">open()</a></i>
is implementation-dependent.
<h4><a name = "tag_008_002_003">&nbsp;</a>Output Modes</h4>
<xref type="3" name="outmodes"></xref>
The
<b>c_oflag</b>
field specifies the terminal
interface's treatment of output, and is composed of the
bitwise inclusive OR of the masks shown, which will be
bitwise distinct.
The mask name symbols in this table are defined
in
<i><a href="../xsh/termios.h.html">&lt;termios.h&gt;</a></i>:
<br>
<p><table  bordercolor=#000000 border=1 align=center><tr valign=top><th align=center><b>Mask Name</b>
<th align=center><b>Description</b>
<tr valign=top><td align=left>OPOST
<td align=left><i>Perform output processing.</i>
<tr valign=top><td align=left>OLCUC
<td align=left><i>Map lower case to upper on output. (<b>LEGACY</b>)</i>
<tr valign=top><td align=left>ONLCR
<td align=left><i>Map NL to CR-NL on output.</i>
<tr valign=top><td align=left>OCRNL
<td align=left><i>Map CR to NL on output.</i>
<tr valign=top><td align=left>ONOCR
<td align=left><i>No CR output at column 0.</i>
<tr valign=top><td align=left>ONLRET
<td align=left><i>NL performs CR function.</i>
<tr valign=top><td align=left>OFILL
<td align=left><i>Use fill characters for delay.</i>
<tr valign=top><td align=left>OFDEL
<td align=left><i>Fill is DEL, else NUL.</i>
<tr valign=top><td align=left>NLDLY
<td align=left><i>Select newline delays:</i>
<tr valign=top><td align=left>NL0
<td align=left><i>Newline character type 0</i>
<tr valign=top><td align=left>NL1
<td align=left><i>Newline character type 1.</i>
<tr valign=top><td align=left>CRDLY
<td align=left><i>Select carriage-return delays:</i>
<tr valign=top><td align=left>CR0
<td align=left><i>Carriage-return delay type 0</i>
<tr valign=top><td align=left>CR1
<td align=left><i>Carriage-return delay type 1</i>
<tr valign=top><td align=left>CR2
<td align=left><i>Carriage-return delay type 2</i>
<tr valign=top><td align=left>CR3
<td align=left><i>Carriage-return delay type 3.</i>
<tr valign=top><td align=left>TABDLY
<td align=left><i>Select horizontal-tab delays:</i>
<tr valign=top><td align=left>TAB0
<td align=left><i>Horizontal-tab delay type 0</i>
<tr valign=top><td align=left>TAB1
<td align=left><i>Horizontal-tab delay type 1</i>
<tr valign=top><td align=left>TAB2
<td align=left><i>Horizontal-tab delay type 2.</i>
<tr valign=top><td align=left>TAB3
<td align=left><i>Expand tabs to spaces.</i>
<tr valign=top><td align=left>BSDLY
<td align=left><i>Select backspace delays:</i>
<tr valign=top><td align=left>BS0
<td align=left><i>Backspace-delay type 0</i>
<tr valign=top><td align=left>BS1
<td align=left><i>Backspace-delay type 1.</i>
<tr valign=top><td align=left>VTDLY
<td align=left><i>Select vertical-tab delays:</i>
<tr valign=top><td align=left>VT0
<td align=left><i>Vertical-tab delay type 0</i>
<tr valign=top><td align=left>VT1
<td align=left><i>Vertical-tab delay type 1.</i>
<tr valign=top><td align=left>FFDLY
<td align=left><i>Select form-feed delays:</i>
<tr valign=top><td align=left>FF0
<td align=left><i>Form-feed delay type 0</i>
<tr valign=top><td align=left>FF1
<td align=left><i>Form-feed delay type 1.</i>
</table>
<p>
If OPOST is set, output data
is post-processed
as described below, so that
lines of text are modified to
appear appropriately on the terminal device; otherwise,
characters are transmitted without change.
<p>
If OLCUC is set,
lower- to upper-case mappings are performed
on the characters before they are transmitted.
In locales other than the POSIX locale,
the mapping is unspecified.
(<b>LEGACY</b>) 
<p>
If ONLCR is set, the NL
character is transmitted as the CR-NL
character pair.
If OCRNL
is set, the CR character is transmitted as the NL character.
If ONOCR is set, no CR
character is transmitted when at column 0 (first position).
If ONLRET is set, the NL
character is assumed to do the carriage-return function;
the column pointer will be set to 0 and the delays specified
for CR will be used.
Otherwise the NL
character is assumed
to do just the line-feed function;
the column pointer will remain unchanged.
The column pointer is also set to 0 if the CR
character is actually transmitted.
<p>
The delay bits specify how long
transmission stops to allow for mechanical or other movement
when certain characters are sent to the terminal.
In all cases a value of 0 indicates no delay.
If OFILL
is set,
fill characters will be transmitted
for delay instead of a timed delay.
This is useful for high baud rate terminals
which need only a minimal delay.
If OFDEL
is set,
the fill character is DEL,
otherwise NUL.
<p>
If a form-feed or vertical-tab delay is specified,
it lasts for about 2 seconds.
<p>
New-line delay lasts about 0.10 seconds.
If ONLRET
is set, the carriage-return delays are
used instead of the newline delays.
If OFILL
is set,
two fill characters will be transmitted.
<p>
Carriage-return delay type 1 is dependent on the current column
position,
type 2 is about 0.10 seconds,
and type 3 is about 0.15 seconds.
If OFILL is set,
delay type 1 transmits two fill characters,
and type 2, four fill characters.
<p>
Horizontal-tab delay type 1 is dependent on the current
column position.
Type 2 is about 0.10 seconds.
Type 3 specifies that tabs are to be expanded into spaces.
If OFILL
is set,
two fill characters will be transmitted for any delay.
<p>
Backspace delay lasts about 0.05 seconds.
If OFILL
is set,
one fill character will be transmitted.
<p>
The actual delays depend on line speed and system load.
<p>
The initial output control value after
<i><a href="../xsh/open.html">open()</a></i>
is implementation-dependent.
<h4><a name = "tag_008_002_004">&nbsp;</a>Control Modes</h4>
<xref type="3" name="conmodes"></xref>
The
<b>c_cflag</b>
field describes the hardware control of the terminal,
and is composed of the bitwise inclusive OR of the masks shown, which will be
bitwise distinct.
The mask name symbols in this table are defined in
<i><a href="../xsh/termios.h.html">&lt;termios.h&gt;</a></i>;