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| author | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:55:15 -0400 |
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| committer | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-25 19:55:15 -0400 |
| commit | 253e67c8b3a72b3a4757fdbc5845297628db0a4a (patch) | |
| tree | adf53b66087aa30dfbf8bf391a1dadb044c3bf4d /static/netbsd/man4/termios.4 4.html | |
| parent | a9157ce950dfe2fc30795d43b9d79b9d1bffc48b (diff) | |
docs: Added All NetBSD Manuals
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diff --git a/static/netbsd/man4/termios.4 4.html b/static/netbsd/man4/termios.4 4.html new file mode 100644 index 00000000..adca8dac --- /dev/null +++ b/static/netbsd/man4/termios.4 4.html @@ -0,0 +1,1035 @@ +<table class="head"> + <tr> + <td class="head-ltitle">TERMIOS(4)</td> + <td class="head-vol">Device Drivers Manual</td> + <td class="head-rtitle">TERMIOS(4)</td> + </tr> +</table> +<div class="manual-text"> +<section class="Sh"> +<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1> +<p class="Pp"><code class="Nm">termios</code> — <span class="Nd">general + terminal line discipline</span></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1> +<p class="Pp"><code class="In">#include + <<a class="In">termios.h</a>></code></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1> +<p class="Pp">This describes a general terminal line discipline that is + supported on tty asynchronous communication ports.</p> +<section class="Ss"> +<h2 class="Ss" id="Opening_a_Terminal_Device_File"><a class="permalink" href="#Opening_a_Terminal_Device_File">Opening + a Terminal Device File</a></h2> +<p class="Pp">When a terminal file is opened, it normally causes the process to + wait until a connection is established. For most hardware, the presence of a + connection is indicated by the assertion of the hardware + <a class="permalink" href="#CARRIER"><i class="Em" id="CARRIER">CARRIER + DETECT</i></a> (CD) line. If the <code class="Nm">termios</code> structure + associated with the terminal file has the <code class="Dv">CLOCAL</code> + flag set in the cflag, or if the <code class="Dv">O_NONBLOCK</code> flag is + set in the <a class="Xr">open(2)</a> call, then the open will succeed even + without a connection being present.</p> +<p class="Pp">In practice, applications seldom open these files; they are opened + by special programs, such as <a class="Xr">getty(8)</a> or + <a class="Xr">rlogind(8)</a>, and become an application's standard input, + output, and error files.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Job_Control_in_a_Nutshell"><a class="permalink" href="#Job_Control_in_a_Nutshell">Job + Control in a Nutshell</a></h2> +<p class="Pp">Every process is associated with a particular process group and + session. The grouping is hierarchical: every member of a particular process + group is a member of the same session. This structuring is used in managing + groups of related processes for purposes of + <a class="permalink" href="#job"><i class="Em" id="job">job control</i></a>; + that is, the ability from the keyboard (or from program control) to + simultaneously stop or restart a complex command (a command composed of one + or more related processes).</p> +<p class="Pp">The grouping into process groups allows delivering of signals that + stop or start the group as a whole, along with arbitrating which process + group has access to the single controlling terminal. The grouping at a + higher layer into sessions is to restrict the job control related signals + and system calls to within processes resulting from a particular instance of + a "login".</p> +<p class="Pp">Typically, a session is created when a user logs in, and the login + terminal is set up to be the controlling terminal; all processes spawned + from that login shell are in the same session, and inherit the controlling + terminal. A job control shell operating interactively (that is, reading + commands from a terminal) normally groups related processes together by + placing them into the same process group. A set of processes in the same + process group is collectively referred to as a "job".</p> +<p class="Pp" id="foreground">When the foreground process group of the terminal + is the same as the process group of a particular job, that job is said to be + in the + <a class="permalink" href="#foreground"><i class="Em">foreground</i></a>. + When the process group of the terminal is different than the process group + of a job (but is still the controlling terminal), that job is said to be in + the + <a class="permalink" href="#background"><i class="Em" id="background">background</i></a>.</p> +<p class="Pp">Normally the shell reads a command and starts the job that + implements that command. If the command is to be started in the foreground + (typical), it sets the process group of the terminal to the process group of + the started job, waits for the job to complete, and then sets the process + group of the terminal back to its own process group (it puts itself into the + foreground).</p> +<p class="Pp">If the job is to be started in the background (as denoted by the + shell operator "&"), it never changes the process group of the + terminal and doesn't wait for the job to complete (that is, it immediately + attempts to read the next command).</p> +<p class="Pp">If the job is started in the foreground, the user may type a + character (usually ‘<code class="Li">^Z</code>’) which + generates the terminal stop signal (<code class="Dv">SIGTSTP</code>) and has + the affect of stopping the entire job. The shell will notice that the job + stopped (see <a class="Xr">wait(2)</a>), and will resume running after + placing itself in the foreground.</p> +<p class="Pp">The shell also has commands for placing stopped jobs in the + background, and for placing stopped or background jobs into the + foreground.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Orphaned_Process_Groups"><a class="permalink" href="#Orphaned_Process_Groups">Orphaned + Process Groups</a></h2> +<p class="Pp">An orphaned process group is a process group that has no process + whose parent is in a different process group, yet is in the same session. + Conceptually it means a process group that doesn't have a parent that could + do anything if it were to be stopped. For example, the initial login shell + is typically in an orphaned process group. Orphaned process groups are + immune to keyboard generated stop signals and job control signals resulting + from reads or writes to the controlling terminal.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="The_Controlling_Terminal"><a class="permalink" href="#The_Controlling_Terminal">The + Controlling Terminal</a></h2> +<p class="Pp">A terminal may belong to a process as its controlling terminal. + Each process of a session that has a controlling terminal has the same + controlling terminal. A terminal may be the controlling terminal for at most + one session. The controlling terminal for a session is allocated by the + session leader by issuing the <code class="Dv">TIOCSCTTY</code> ioctl. A + controlling terminal is never acquired by merely opening a terminal device + file. When a controlling terminal becomes associated with a session, its + foreground process group is set to the process group of the session + leader.</p> +<p class="Pp">The controlling terminal is inherited by a child process during a + <a class="Xr">fork(2)</a> function call. A process relinquishes its + controlling terminal when it creates a new session with the + <a class="Xr">setsid(2)</a> function; other processes remaining in the old + session that had this terminal as their controlling terminal continue to + have it. A process does not relinquish its controlling terminal simply by + closing all of its file descriptors associated with the controlling terminal + if other processes continue to have it open.</p> +<p class="Pp">When a controlling process terminates, the controlling terminal is + disassociated from the current session, allowing it to be acquired by a new + session leader. Subsequent access to the terminal by other processes in the + earlier session will be denied, with attempts to access the terminal treated + as if modem disconnect had been sensed.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Terminal_Access_Control"><a class="permalink" href="#Terminal_Access_Control">Terminal + Access Control</a></h2> +<p class="Pp">If a process is in the foreground process group of its controlling + terminal, read operations are allowed. Any attempts by a process in a + background process group to read from its controlling terminal causes a + <code class="Dv">SIGTTIN</code> signal to be sent to the process's group + unless one of the following special cases apply: If the reading process is + ignoring or blocking the <code class="Dv">SIGTTIN</code> signal, or if the + process group of the reading process is orphaned, the + <a class="Xr">read(2)</a> returns -1 with <var class="Va">errno set to</var> + <code class="Er">EIO</code> and no signal is sent. The default action of the + <code class="Dv">SIGTTIN</code> signal is to stop the process to which it is + sent.</p> +<p class="Pp">If a process is in the foreground process group of its controlling + terminal, write operations are allowed. Attempts by a process in a + background process group to write to its controlling terminal will cause the + process group to be sent a <code class="Dv">SIGTTOU</code> signal unless one + of the following special cases apply: If <code class="Dv">TOSTOP</code> is + not set, or if <code class="Dv">TOSTOP</code> is set and the process is + ignoring or blocking the <code class="Dv">SIGTTOU</code> signal, the process + is allowed to write to the terminal and the <code class="Dv">SIGTTOU</code> + signal is not sent. If <code class="Dv">TOSTOP</code> is set, and the + process group of the writing process is orphaned, and the writing process is + not ignoring or blocking <code class="Dv">SIGTTOU</code>, the + <a class="Xr">write(2)</a> returns -1 with errno set to + <code class="Er">EIO</code> and no signal is sent.</p> +<p class="Pp">Certain calls that set terminal parameters are treated in the same + fashion as write, except that <code class="Dv">TOSTOP</code> is ignored; + that is, the effect is identical to that of terminal writes when + <code class="Dv">TOSTOP</code> is set.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Input_Processing_and_Reading_Data"><a class="permalink" href="#Input_Processing_and_Reading_Data">Input + Processing and Reading Data</a></h2> +<p class="Pp">A terminal device associated with a terminal device file may + operate in full-duplex mode, so that data may arrive even while output is + occurring. Each terminal device file has associated with it an input queue, + into which incoming data is stored by the system before being read by a + process. The system imposes a limit, {<code class="Dv">MAX_INPUT</code>}, on + the number of bytes that may be stored in the input queue. The behavior of + the system when this limit is exceeded depends on the setting of the + <code class="Dv">IMAXBEL</code> flag in the <code class="Nm">termios</code> + <var class="Fa">c_iflag</var>. If this flag is set, the terminal is sent an + ASCII <code class="Dv">BEL</code> character each time a character is + received while the input queue is full. Otherwise, the input queue is + flushed upon receiving the character.</p> +<p class="Pp">Two general kinds of input processing are available, determined by + whether the terminal device file is in canonical mode or noncanonical mode. + Additionally, input characters are processed according to the + <var class="Fa">c_iflag</var> and <var class="Fa">c_lflag</var> fields. Such + processing can include echoing, which in general means transmitting input + characters immediately back to the terminal when they are received from the + terminal. This is useful for terminals that can operate in full-duplex + mode.</p> +<p class="Pp">The manner in which data is provided to a process reading from a + terminal device file is dependent on whether the terminal device file is in + canonical or noncanonical mode.</p> +<p class="Pp">Another dependency is whether the + <code class="Dv">O_NONBLOCK</code> flag is set by <a class="Xr">open(2)</a> + or <a class="Xr">fcntl(2)</a>. If the <code class="Dv">O_NONBLOCK</code> + flag is clear, then the read request is blocked until data is available or a + signal has been received. If the <code class="Dv">O_NONBLOCK</code> flag is + set, then the read request is completed, without blocking, in one of three + ways:</p> +<ol class="Bl-enum Bd-indent"> + <li>If there is enough data available to satisfy the entire request, and the + read completes successfully the number of bytes read is returned.</li> + <li>If there is not enough data available to satisfy the entire request, and + the read completes successfully, having read as much data as possible, the + number of bytes read is returned.</li> + <li>If there is no data available, the read returns -1, with errno set to + <code class="Er">EAGAIN</code>.</li> +</ol> +<p class="Pp">When data is available depends on whether the input processing + mode is canonical or noncanonical.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Canonical_Mode_Input_Processing"><a class="permalink" href="#Canonical_Mode_Input_Processing">Canonical + Mode Input Processing</a></h2> +<p class="Pp">In canonical mode input processing, terminal input is processed in + units of lines. A line is delimited by a newline + ‘<code class="Li">\n</code>’ character, an end-of-file + (<code class="Dv">EOF</code>) character, or an end-of-line + (<code class="Dv">EOL</code>) character. See the + <a class="Sx" href="#Special_Characters">Special Characters</a> section for + more information on <code class="Dv">EOF</code> and + <code class="Dv">EOL</code>. This means that a read request will not return + until an entire line has been typed, or a signal has been received. Also, no + matter how many bytes are requested in the read call, at most one line is + returned. It is not, however, necessary to read a whole line at once; any + number of bytes, even one, may be requested in a read without losing + information.</p> +<p class="Pp">{<code class="Dv">MAX_CANON</code>} is a limit on the number of + bytes in a line. The behavior of the system when this limit is exceeded is + the same as when the input queue limit {<code class="Dv">MAX_INPUT</code>}, + is exceeded.</p> +<p class="Pp">Erase and kill processing occur when either of two special + characters, the <code class="Dv">ERASE</code> and + <code class="Dv">KILL</code> characters (see the + <a class="Sx" href="#Special_Characters">Special Characters</a> section), is + received. This processing affects data in the input queue that has not yet + been delimited by a newline <code class="Dv">NL</code>, + <code class="Dv">EOF</code>, or <code class="Dv">EOL</code> character. This + un-delimited data makes up the current line. The + <code class="Dv">ERASE</code> character deletes the last character in the + current line, if there is any. The <code class="Dv">KILL</code> character + deletes all data in the current line, if there is any. The + <code class="Dv">ERASE</code> and <code class="Dv">KILL</code> characters + have no effect if there is no data in the current line. The + <code class="Dv">ERASE</code> and <code class="Dv">KILL</code> characters + themselves are not placed in the input queue.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Noncanonical_Mode_Input_Processing"><a class="permalink" href="#Noncanonical_Mode_Input_Processing">Noncanonical + Mode Input Processing</a></h2> +<p class="Pp">In noncanonical mode input processing, input bytes are not + assembled into lines, and erase and kill processing does not occur. The + values of the <code class="Dv">VMIN</code> and <code class="Dv">VTIME</code> + members of the <var class="Fa">c_cc</var> array are used to determine how to + process the bytes received.</p> +<p class="Pp"><code class="Dv">VMIN</code> represents the minimum number of + bytes that should be received when the <a class="Xr">read(2)</a> system call + successfully returns. <code class="Dv">VTIME</code> is a timer of 0.1 second + granularity that is used to time out bursty and short term data + transmissions. If <code class="Dv">VMIN</code> is greater than + {<code class="Dv">MAX_INPUT</code>}, the response to the request is + undefined. The four possible values for <code class="Dv">VMIN</code> and + <code class="Dv">VTIME</code> and their interactions are described + below.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Case_A:_VMIN___0,_VTIME___0"><a class="permalink" href="#Case_A:_VMIN___0,_VTIME___0">Case + A: VMIN > 0, VTIME > 0</a></h2> +<p class="Pp">In this case <code class="Dv">VTIME</code> serves as an inter-byte + timer and is activated after the first byte is received. Since it is an + inter-byte timer, it is reset after a byte is received. The interaction + between <code class="Dv">VMIN</code> and <code class="Dv">VTIME</code> is as + follows: as soon as one byte is received, the inter-byte timer is started. + If <code class="Dv">VMIN</code> bytes are received before the inter-byte + timer expires (remember that the timer is reset upon receipt of each byte), + the read is satisfied. If the timer expires before + <code class="Dv">VMIN</code> bytes are received, the characters received to + that point are returned to the user. Note that if + <code class="Dv">VTIME</code> expires at least one byte is returned because + the timer would not have been enabled unless a byte was received. In this + case (<code class="Dv">VMIN</code> > 0, <code class="Dv">VTIME</code> + > 0) the read blocks until the <code class="Dv">VMIN</code> and + <code class="Dv">VTIME</code> mechanisms are activated by the receipt of the + first byte, or a signal is received. If data is in the buffer at the time of + the <a class="Xr">read(2)</a>, the result is as if data had been received + immediately after the <a class="Xr">read(2)</a>.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Case_B:_VMIN___0,_VTIME_=_0"><a class="permalink" href="#Case_B:_VMIN___0,_VTIME_=_0">Case + B: VMIN > 0, VTIME = 0</a></h2> +<p class="Pp">In this case, since the value of <code class="Dv">VTIME</code> is + zero, the timer plays no role and only <code class="Dv">VMIN</code> is + significant. A pending read is not satisfied until + <code class="Dv">VMIN</code> bytes are received (i.e., the pending read + blocks until <code class="Dv">VMIN</code> bytes are received), or a signal + is received. A program that uses this case to read record-based terminal + <code class="Dv">I/O</code> may block indefinitely in the read + operation.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Case_C:_VMIN_=_0,_VTIME___0"><a class="permalink" href="#Case_C:_VMIN_=_0,_VTIME___0">Case + C: VMIN = 0, VTIME > 0</a></h2> +<p class="Pp">In this case, since <code class="Dv">VMIN</code> = 0, + <code class="Dv">VTIME</code> no longer represents an inter-byte timer. It + now serves as a read timer that is activated as soon as the read function is + processed. A read is satisfied as soon as a single byte is received or the + read timer expires. Note that in this case if the timer expires, no bytes + are returned. If the timer does not expire, the only way the read can be + satisfied is if a byte is received. In this case the read will not block + indefinitely waiting for a byte; if no byte is received within + <code class="Dv">VTIME</code>*0.1 seconds after the read is initiated, the + read returns a value of zero, having read no data. If data is in the buffer + at the time of the read, the timer is started as if data had been received + immediately after the read.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Case_D:_VMIN_=_0,_VTIME_=_0"><a class="permalink" href="#Case_D:_VMIN_=_0,_VTIME_=_0">Case + D: VMIN = 0, VTIME = 0</a></h2> +<p class="Pp">The minimum of either the number of bytes requested or the number + of bytes currently available is returned without waiting for more bytes to + be input. If no characters are available, read returns a value of zero, + having read no data.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Writing_Data_and_Output_Processing"><a class="permalink" href="#Writing_Data_and_Output_Processing">Writing + Data and Output Processing</a></h2> +<p class="Pp">When a process writes one or more bytes to a terminal device file, + they are processed according to the <var class="Fa">c_oflag</var> field (see + the <a class="Sx" href="#Output_Modes">Output Modes</a> section). The + implementation may provide a buffering mechanism; as such, when a call to + <a class="Xr">write(2)</a> completes, all of the bytes written have been + scheduled for transmission to the device, but the transmission will not + necessarily have been completed.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Special_Characters"><a class="permalink" href="#Special_Characters">Special + Characters</a></h2> +<p class="Pp">Certain characters have special functions on input or output or + both. These functions are summarized as follows:</p> +<dl class="Bl-tag"> + <dt id="INTR"><a class="permalink" href="#INTR"><code class="Dv">INTR</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ISIG</code> flag (see the + <a class="Sx" href="#Local_Modes">Local Modes</a> section) is enabled. + Generates a <code class="Dv">SIGINT</code> signal which is sent to all + processes in the foreground process group for which the terminal is the + controlling terminal. If <code class="Dv">ISIG</code> is set, the + <code class="Dv">INTR</code> character is discarded when processed.</dd> + <dt id="QUIT"><a class="permalink" href="#QUIT"><code class="Dv">QUIT</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ISIG</code> flag is enabled. Generates a + <code class="Dv">SIGQUIT</code> signal which is sent to all processes in + the foreground process group for which the terminal is the controlling + terminal. If <code class="Dv">ISIG</code> is set, the + <code class="Dv">QUIT</code> character is discarded when processed.</dd> + <dt id="ERASE"><a class="permalink" href="#ERASE"><code class="Dv">ERASE</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. Erases the last character in + the current line; see + <a class="Sx" href="#Canonical_Mode_Input_Processing">Canonical Mode Input + Processing</a>. It does not erase beyond the start of a line, as delimited + by an <code class="Dv">NL</code>, <code class="Dv">EOF</code>, or + <code class="Dv">EOL</code> character. If <code class="Dv">ICANON</code> + is set, the <code class="Dv">ERASE</code> character is discarded when + processed.</dd> + <dt id="KILL"><a class="permalink" href="#KILL"><code class="Dv">KILL</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. Deletes the entire line, as + delimited by a <code class="Dv">NL</code>, <code class="Dv">EOF</code>, or + <code class="Dv">EOL</code> character. If <code class="Dv">ICANON</code> + is set, the <code class="Dv">KILL</code> character is discarded when + processed.</dd> + <dt id="EOF"><a class="permalink" href="#EOF"><code class="Dv">EOF</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. When received, all the bytes + waiting to be read are immediately passed to the process, without waiting + for a newline, and the <code class="Dv">EOF</code> is discarded. Thus, if + there are no bytes waiting (that is, the <code class="Dv">EOF</code> + occurred at the beginning of a line), a byte count of zero is returned + from the <a class="Xr">read(2)</a>, representing an end-of-file + indication. If <code class="Dv">ICANON</code> is set, the + <code class="Dv">EOF</code> character is discarded when processed.</dd> + <dt id="NL"><a class="permalink" href="#NL"><code class="Dv">NL</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. It is the line delimiter + ‘<code class="Li">\n</code>’.</dd> + <dt id="EOL"><a class="permalink" href="#EOL"><code class="Dv">EOL</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. Is an additional line + delimiter, like <code class="Dv">NL</code>.</dd> + <dt id="SUSP"><a class="permalink" href="#SUSP"><code class="Dv">SUSP</code></a></dt> + <dd>If the <code class="Dv">ISIG</code> flag is enabled, receipt of the + <code class="Dv">SUSP</code> character causes a + <code class="Dv">SIGTSTP</code> signal to be sent to all processes in the + foreground process group for which the terminal is the controlling + terminal, and the <code class="Dv">SUSP</code> character is discarded when + processed.</dd> + <dt id="STOP"><a class="permalink" href="#STOP"><code class="Dv">STOP</code></a></dt> + <dd>Special character on both input and output and is recognized if the + <code class="Dv">IXON</code> (output control) or + <code class="Dv">IXOFF</code> (input control) flag is set. Can be used to + temporarily suspend output. It is useful with fast terminals to prevent + output from disappearing before it can be read. If + <code class="Dv">IXON</code> is set, the <code class="Dv">STOP</code> + character is discarded when processed.</dd> + <dt id="START"><a class="permalink" href="#START"><code class="Dv">START</code></a></dt> + <dd>Special character on both input and output and is recognized if the + <code class="Dv">IXON</code> (output control) or + <code class="Dv">IXOFF</code> (input control) flag is set. Can be used to + resume output that has been suspended by a <code class="Dv">STOP</code> + character. If <code class="Dv">IXON</code> is set, the + <code class="Dv">START</code> character is discarded when processed.</dd> + <dt id="CR"><a class="permalink" href="#CR"><code class="Dv">CR</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set; it is the + ‘<code class="Li">\r</code>’, as denoted in the C Standard + {2}. When <code class="Dv">ICANON</code> and <code class="Dv">ICRNL</code> + are set and <code class="Dv">IGNCR</code> is not set, this character is + translated into a <code class="Dv">NL</code>, and has the same effect as a + <code class="Dv">NL</code> character.</dd> +</dl> +<p class="Pp">The following special characters are extensions defined by this + system and are not a part of <span class="St">IEEE Std 1003.1 + (“POSIX.1”)</span> <code class="Nm">termios</code>.</p> +<dl class="Bl-tag"> + <dt id="EOL2"><a class="permalink" href="#EOL2"><code class="Dv">EOL2</code></a></dt> + <dd>Secondary <code class="Dv">EOL</code> character. Same function as + <code class="Dv">EOL</code>.</dd> + <dt id="WERASE"><a class="permalink" href="#WERASE"><code class="Dv">WERASE</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. Erases the last word in the + current line according to one of two algorithms. If the + <code class="Dv">ALTWERASE</code> flag is not set, first any preceding + whitespace is erased, and then the maximal sequence of non-whitespace + characters. If <code class="Dv">ALTWERASE</code> is set, first any + preceding whitespace is erased, and then the maximal sequence of + alphabetic/underscores or non alphabetic/underscores. As a special case in + this second algorithm, the first previous non-whitespace character is + skipped in determining whether the preceding word is a sequence of + alphabetic/underscores. This sounds confusing but turns out to be quite + practical.</dd> + <dt id="REPRINT"><a class="permalink" href="#REPRINT"><code class="Dv">REPRINT</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. Causes the current input edit + line to be retyped.</dd> + <dt id="DSUSP"><a class="permalink" href="#DSUSP"><code class="Dv">DSUSP</code></a></dt> + <dd>Has similar actions to the <code class="Dv">SUSP</code> character, except + that the <code class="Dv">SIGTSTP</code> signal is delivered when one of + the processes in the foreground process group issues a + <a class="Xr">read(2)</a> to the controlling terminal.</dd> + <dt id="LNEXT"><a class="permalink" href="#LNEXT"><code class="Dv">LNEXT</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">IEXTEN</code> flag is set. Receipt of this character + causes the next character to be taken literally.</dd> + <dt id="DISCARD"><a class="permalink" href="#DISCARD"><code class="Dv">DISCARD</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">IEXTEN</code> flag is set. Receipt of this character + toggles the flushing of terminal output.</dd> + <dt id="STATUS"><a class="permalink" href="#STATUS"><code class="Dv">STATUS</code></a></dt> + <dd>Special character on input and is recognized if the + <code class="Dv">ICANON</code> flag is set. Receipt of this character + causes a <code class="Dv">SIGINFO</code> signal to be sent to the + foreground process group of the terminal. Also, if the + <code class="Dv">NOKERNINFO</code> flag is not set, it causes the kernel + to write a status message to the terminal that displays the current load + average, the name of the command in the foreground, its process ID, the + symbolic wait channel, the number of user and system seconds used, the + percentage of CPU the process is getting, and the resident set size of the + process.</dd> +</dl> +<p class="Pp">The <code class="Dv">NL</code> and <code class="Dv">CR</code> + characters cannot be changed. The values for all the remaining characters + can be set and are described later in the document under Special Control + Characters.</p> +<p class="Pp">Special character functions associated with changeable special + control characters can be disabled individually by setting their value to + {<code class="Dv">_POSIX_VDISABLE</code>}; see + <a class="Sx" href="#Special_Control_Characters">Special Control + Characters</a>.</p> +<p class="Pp">If two or more special characters have the same value, the + function performed when that character is received is undefined.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Modem_Disconnect"><a class="permalink" href="#Modem_Disconnect">Modem + Disconnect</a></h2> +<p class="Pp">If a modem disconnect is detected by the terminal interface for a + controlling terminal, and if <code class="Dv">CLOCAL</code> is not set in + the <var class="Fa">c_cflag</var> field for the terminal, the + <code class="Dv">SIGHUP</code> signal is sent to the controlling process + associated with the terminal. Unless other arrangements have been made, this + causes the controlling process to terminate. Any subsequent call to the + <a class="Xr">read(2)</a> function returns the value zero, indicating end of + file. Thus, processes that read a terminal file and test for end-of-file can + terminate appropriately after a disconnect. Any subsequent + <a class="Xr">write(2)</a> to the terminal device returns -1, with + <var class="Va">errno</var> set to <code class="Er">EIO</code>, until the + device is closed.</p> +</section> +</section> +<section class="Sh"> +<h1 class="Sh" id="GENERAL_TERMINAL_INTERFACE"><a class="permalink" href="#GENERAL_TERMINAL_INTERFACE">GENERAL + TERMINAL INTERFACE</a></h1> +<section class="Ss"> +<h2 class="Ss" id="Closing_a_Terminal_Device_File"><a class="permalink" href="#Closing_a_Terminal_Device_File">Closing + a Terminal Device File</a></h2> +<p class="Pp">The last process to close a terminal device file causes any output + to be sent to the device and any input to be discarded. Then, if + <code class="Dv">HUPCL</code> is set in the control modes, and the + communications port supports a disconnect function, the terminal device + performs a disconnect.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Parameters_That_Can_Be_Set"><a class="permalink" href="#Parameters_That_Can_Be_Set">Parameters + That Can Be Set</a></h2> +<p class="Pp">Routines that need to control certain terminal I/O characteristics + do so by using the <code class="Nm">termios</code> structure as defined in + the header <code class="In"><<a class="In">termios.h</a>></code>. This + structure contains minimally four scalar elements of bit flags and one array + of special characters. The scalar flag elements are named: + <var class="Fa">c_iflag</var>, <var class="Fa">c_oflag</var>, + <var class="Fa">c_cflag</var>, and <var class="Fa">c_lflag</var>. The + character array is named <var class="Fa">c_cc</var>, and its maximum index + is <code class="Dv">NCCS</code>.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Input_Modes"><a class="permalink" href="#Input_Modes">Input + Modes</a></h2> +<p class="Pp">Values of the <var class="Fa">c_iflag</var> field describe the + basic terminal input control, and are composed of following masks:</p> +<p class="Pp"></p> +<div class="Bd-indent"> +<dl class="Bl-tag Bl-compact"> + <dt id="IGNBRK"><a class="permalink" href="#IGNBRK"><code class="Dv">IGNBRK</code></a></dt> + <dd>/* ignore BREAK condition */</dd> + <dt id="BRKINT"><a class="permalink" href="#BRKINT"><code class="Dv">BRKINT</code></a></dt> + <dd>/* map BREAK to SIGINT */</dd> + <dt id="IGNPAR"><a class="permalink" href="#IGNPAR"><code class="Dv">IGNPAR</code></a></dt> + <dd>/* ignore (discard) parity errors */</dd> + <dt id="PARMRK"><a class="permalink" href="#PARMRK"><code class="Dv">PARMRK</code></a></dt> + <dd>/* mark parity and framing errors */</dd> + <dt id="INPCK"><a class="permalink" href="#INPCK"><code class="Dv">INPCK</code></a></dt> + <dd>/* enable checking of parity errors */</dd> + <dt id="ISTRIP"><a class="permalink" href="#ISTRIP"><code class="Dv">ISTRIP</code></a></dt> + <dd>/* strip 8th bit off chars */</dd> + <dt id="INLCR"><a class="permalink" href="#INLCR"><code class="Dv">INLCR</code></a></dt> + <dd>/* map NL into CR */</dd> + <dt id="IGNCR"><a class="permalink" href="#IGNCR"><code class="Dv">IGNCR</code></a></dt> + <dd>/* ignore CR */</dd> + <dt id="ICRNL"><a class="permalink" href="#ICRNL"><code class="Dv">ICRNL</code></a></dt> + <dd>/* map CR to NL (ala CRMOD) */</dd> + <dt id="IXON"><a class="permalink" href="#IXON"><code class="Dv">IXON</code></a></dt> + <dd>/* enable output flow control */</dd> + <dt id="IXOFF"><a class="permalink" href="#IXOFF"><code class="Dv">IXOFF</code></a></dt> + <dd>/* enable input flow control */</dd> + <dt id="IXANY"><a class="permalink" href="#IXANY"><code class="Dv">IXANY</code></a></dt> + <dd>/* any char will restart after stop */</dd> + <dt id="IMAXBEL"><a class="permalink" href="#IMAXBEL"><code class="Dv">IMAXBEL</code></a></dt> + <dd>/* ring bell on input queue full */</dd> +</dl> +</div> +<p class="Pp">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 + defined.</p> +<p class="Pp">If <code class="Dv">IGNBRK</code> 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 <code class="Dv">IGNBRK</code> is not + set and <code class="Dv">BRKINT</code> is set, the break condition flushes + the input and output queues and if the terminal is the controlling terminal + of a foreground process group, the break condition generates a single + <code class="Dv">SIGINT</code> signal to that foreground process group. If + neither <code class="Dv">IGNBRK</code> nor <code class="Dv">BRKINT</code> is + set, a break condition is read as a single + ‘<code class="Li">\0</code>’, or if + <code class="Dv">PARMRK</code> is set, as + ‘<code class="Li">\377</code>’, + ‘<code class="Li">\0</code>’, + ‘<code class="Li">\0</code>’.</p> +<p class="Pp">If <code class="Dv">IGNPAR</code> is set, a byte with a framing or + parity error (other than break) is ignored.</p> +<p class="Pp">If <code class="Dv">PARMRK</code> is set, and + <code class="Dv">IGNPAR</code> is not set, a byte with a framing or parity + error (other than break) is given to the application as the three-character + sequence ‘<code class="Li">\377</code>’, + ‘<code class="Li">\0</code>’, X, where + ‘<code class="Li">\377</code>’, + ‘<code class="Li">\0</code>’ is a two-character flag preceding + each sequence and X is the data of the character received in error. To avoid + ambiguity in this case, if <code class="Dv">ISTRIP</code> is not set, a + valid character of ‘<code class="Li">\377</code>’ is given to + the application as ‘<code class="Li">\377</code>’, + ‘<code class="Li">\377</code>’. If neither + <code class="Dv">PARMRK</code> nor <code class="Dv">IGNPAR</code> is set, a + framing or parity error (other than break) is given to the application as a + single character ‘<code class="Li">\0</code>’.</p> +<p class="Pp">If <code class="Dv">INPCK</code> is set, input parity checking is + enabled. If <code class="Dv">INPCK</code> 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 + <a class="Sx" href="#Control_Modes">Control Modes</a>). If parity detection + is enabled but input parity checking is disabled, the hardware to which the + terminal is connected recognizes the parity bit, but the terminal special + file does not check whether this bit is set correctly or not.</p> +<p class="Pp">If <code class="Dv">ISTRIP</code> is set, valid input bytes are + first stripped to seven bits, otherwise all eight bits are processed.</p> +<p class="Pp">If <code class="Dv">INLCR</code> is set, a received + <code class="Dv">NL</code> character is translated into a + <code class="Dv">CR</code> character. If <code class="Dv">IGNCR</code> is + set, a received <code class="Dv">CR</code> character is ignored (not read). + If <code class="Dv">IGNCR</code> is not set and + <code class="Dv">ICRNL</code> is set, a received <code class="Dv">CR</code> + character is translated into a <code class="Dv">NL</code> character.</p> +<p class="Pp">If <code class="Dv">IXON</code> is set, start/stop output control + is enabled. A received <code class="Dv">STOP</code> character suspends + output and a received <code class="Dv">START</code> character restarts + output. If <code class="Dv">IXANY</code> is also set, then any character may + restart output. When <code class="Dv">IXON</code> is set, + <code class="Dv">START</code> and <code class="Dv">STOP</code> characters + are not read, but merely perform flow control functions. When + <code class="Dv">IXON</code> is not set, the <code class="Dv">START</code> + and <code class="Dv">STOP</code> characters are read.</p> +<p class="Pp">If <code class="Dv">IXOFF</code> is set, start/stop input control + is enabled. The system shall transmit one or more + <code class="Dv">STOP</code> characters, which are intended to cause the + terminal device to stop transmitting data, as needed to prevent the input + queue from overflowing and causing the undefined behavior described in + <a class="Sx" href="#Input_Processing_and_Reading_Data">Input Processing and + Reading Data</a>, and shall transmit one or more + <code class="Dv">START</code> 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 <code class="Dv">STOP</code> and START + characters are transmitted are implementation defined.</p> +<p class="Pp">If <code class="Dv">IMAXBEL</code> is set and the input queue is + full, subsequent input shall cause an ASCII <code class="Dv">BEL</code> + character to be transmitted to the output queue.</p> +<p class="Pp">The initial input control value after <a class="Xr">open(2)</a> is + implementation defined.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Output_Modes"><a class="permalink" href="#Output_Modes">Output + Modes</a></h2> +<p class="Pp">Values of the <var class="Fa">c_oflag</var> field describe the + basic terminal output control, and are composed of the following masks:</p> +<p class="Pp"></p> +<div class="Bd-indent"> +<dl class="Bl-tag Bl-compact"> + <dt id="OPOST"><a class="permalink" href="#OPOST"><code class="Dv">OPOST</code></a></dt> + <dd>/* enable following output processing */</dd> + <dt id="ONLCR"><a class="permalink" href="#ONLCR"><code class="Dv">ONLCR</code></a></dt> + <dd>/* map NL to CR-NL (ala <code class="Dv">CRMOD</code>) */</dd> + <dt id="OCRNL"><a class="permalink" href="#OCRNL"><code class="Dv">OCRNL</code></a></dt> + <dd>/* map CR to NL */</dd> + <dt id="OXTABS"><a class="permalink" href="#OXTABS"><code class="Dv">OXTABS</code></a></dt> + <dd>/* expand tabs to spaces */</dd> + <dt id="ONOEOT"><a class="permalink" href="#ONOEOT"><code class="Dv">ONOEOT</code></a></dt> + <dd>/* discard <code class="Dv">EOT</code>'s (^D) on output */</dd> + <dt id="ONOCR"><a class="permalink" href="#ONOCR"><code class="Dv">ONOCR</code></a></dt> + <dd>/* do not transmit CRs on column 0 */</dd> + <dt id="ONLRET"><a class="permalink" href="#ONLRET"><code class="Dv">ONLRET</code></a></dt> + <dd>/* on the terminal NL performs the CR function */</dd> +</dl> +</div> +<p class="Pp">If <code class="Dv">OPOST</code> is set, the remaining flag masks + are interpreted as follows; otherwise characters are transmitted without + change.</p> +<p class="Pp">If <code class="Dv">ONLCR</code> is set, newlines are translated + to carriage return, linefeeds.</p> +<p class="Pp">If <code class="Dv">OCRNL</code> is set, carriage returns are + translated to newlines.</p> +<p class="Pp">If <code class="Dv">OXTABS</code> is set, tabs are expanded to the + appropriate number of spaces (assuming 8 column tab stops).</p> +<p class="Pp">If <code class="Dv">ONOEOT</code> is set, ASCII + <code class="Dv">EOT</code>'s are discarded on output.</p> +<p class="Pp">If <code class="Dv">ONOCR</code> is set, no CR character is + transmitted when at column 0 (first position).</p> +<p class="Pp">If <code class="Dv">ONLRET</code> is set, the NL character is + assumed to do the carriage-return function; the column pointer will be set + to 0.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Control_Modes"><a class="permalink" href="#Control_Modes">Control + Modes</a></h2> +<p class="Pp">Values of the <var class="Fa">c_cflag</var> field describe the + basic terminal hardware control, and are composed of the following masks. + Not all values specified are supported by all hardware.</p> +<p class="Pp"></p> +<div class="Bd-indent"> +<dl class="Bl-tag Bl-compact"> + <dt id="CSIZE"><a class="permalink" href="#CSIZE"><code class="Dv">CSIZE</code></a></dt> + <dd>/* character size mask */</dd> + <dt id="CS5"><a class="permalink" href="#CS5"><code class="Dv">CS5</code></a></dt> + <dd>/* 5 bits (pseudo) */</dd> + <dt id="CS6"><a class="permalink" href="#CS6"><code class="Dv">CS6</code></a></dt> + <dd>/* 6 bits */</dd> + <dt id="CS7"><a class="permalink" href="#CS7"><code class="Dv">CS7</code></a></dt> + <dd>/* 7 bits */</dd> + <dt id="CS8"><a class="permalink" href="#CS8"><code class="Dv">CS8</code></a></dt> + <dd>/* 8 bits */</dd> + <dt id="CSTOPB"><a class="permalink" href="#CSTOPB"><code class="Dv">CSTOPB</code></a></dt> + <dd>/* send 2 stop bits */</dd> + <dt id="CREAD"><a class="permalink" href="#CREAD"><code class="Dv">CREAD</code></a></dt> + <dd>/* enable receiver */</dd> + <dt id="PARENB"><a class="permalink" href="#PARENB"><code class="Dv">PARENB</code></a></dt> + <dd>/* parity enable */</dd> + <dt id="PARODD"><a class="permalink" href="#PARODD"><code class="Dv">PARODD</code></a></dt> + <dd>/* odd parity, else even */</dd> + <dt id="HUPCL"><a class="permalink" href="#HUPCL"><code class="Dv">HUPCL</code></a></dt> + <dd>/* hang up on last close */</dd> + <dt id="CLOCAL"><a class="permalink" href="#CLOCAL"><code class="Dv">CLOCAL</code></a></dt> + <dd>/* ignore modem status lines */</dd> + <dt id="CCTS_OFLOW"><a class="permalink" href="#CCTS_OFLOW"><code class="Dv">CCTS_OFLOW</code></a></dt> + <dd>/* <code class="Dv">CTS</code> flow control of output */</dd> + <dt id="CRTSCTS"><a class="permalink" href="#CRTSCTS"><code class="Dv">CRTSCTS</code></a></dt> + <dd>/* logically the same as <code class="Dv">CCTS_OFLOW |</code> + <code class="Dv">CCTS_IFLOW</code> */</dd> + <dt id="CRTS_IFLOW"><a class="permalink" href="#CRTS_IFLOW"><code class="Dv">CRTS_IFLOW</code></a></dt> + <dd>/* RTS flow control of input */</dd> + <dt id="MDMBUF"><a class="permalink" href="#MDMBUF"><code class="Dv">MDMBUF</code></a></dt> + <dd>/* flow control output via Carrier */</dd> +</dl> +</div> +<p class="Pp">The <code class="Dv">CSIZE</code> bits specify the byte size in + bits for both transmission and reception. The <var class="Fa">c_cflag</var> + is masked with <code class="Dv">CSIZE</code> and compared with the values + <code class="Dv">CS5</code>, <code class="Dv">CS6</code>, + <code class="Dv">CS7</code>, or <code class="Dv">CS8</code>. This size does + not include the parity bit, if any. If <code class="Dv">CSTOPB</code> is + set, two stop bits are used, otherwise one stop bit. For example, at 110 + baud, two stop bits are normally used.</p> +<p class="Pp">If <code class="Dv">CREAD</code> is set, the receiver is enabled. + Otherwise, no character is received. Not all hardware supports this bit. In + fact, this flag is pretty silly and if it were not part of the + <code class="Nm">termios</code> specification it would be omitted.</p> +<p class="Pp">If <code class="Dv">PARENB</code> is set, parity generation and + detection are enabled and a parity bit is added to each character. If parity + is enabled, <code class="Dv">PARODD</code> specifies odd parity if set, + otherwise even parity is used.</p> +<p class="Pp">If <code class="Dv">HUPCL</code> is set, the modem control lines + for the port are lowered when the last process with the port open closes the + port or the process terminates. The modem connection is broken.</p> +<p class="Pp">If <code class="Dv">CLOCAL</code> is set, a connection does not + depend on the state of the modem status lines. If + <code class="Dv">CLOCAL</code> is clear, the modem status lines are + monitored.</p> +<p class="Pp">Under normal circumstances, a call to the + <a class="Xr">open(2)</a> function waits for the modem connection to + complete. However, if the <code class="Dv">O_NONBLOCK</code> flag is set or + if <code class="Dv">CLOCAL</code> has been set, the + <a class="Xr">open(2)</a> function returns immediately without waiting for + the connection.</p> +<p class="Pp">If the <a class="Xr">tty(4)</a> + <code class="Dv">TIOCFLAG_CLOCAL</code> flag has been set on the port then + the <code class="Dv">CLOCAL</code> flag will automatically be set on every + open.</p> +<p class="Pp">The <code class="Dv">CCTS_OFLOW</code> and + <code class="Dv">CRTS_IFLOW</code> flags are currently unused. Only + <code class="Dv">CRTSCTS</code>, which has the combined effect, is + implemented. Note that <code class="Dv">CRTSCTS</code> support is hardware + and driver dependent. Check the specific port driver manual page to see if + hardware flow control is supported on the port you are using.</p> +<p class="Pp">If the <a class="Xr">tty(4)</a> + <code class="Dv">TIOCFLAG_CRTSCTS</code> flag has been set on the port then + the <code class="Dv">CRTSCTS</code> flag will automatically be set on every + open.</p> +<p class="Pp">If <code class="Dv">MDMBUF</code> is set then output flow control + is controlled by the state of Carrier Detect.</p> +<p class="Pp">If the <a class="Xr">tty(4)</a> + <code class="Dv">TIOCFLAG_MDMBUF</code> flag has been set on the port then + the <code class="Dv">MDMBUF</code> flag will automatically be set on every + open.</p> +<p class="Pp">If the object for which the control modes are set is not an + asynchronous serial connection, some of the modes may be ignored; for + example, if an attempt is made to set the baud rate on a network connection + to a terminal on another host, the baud rate may or may not be set on the + connection between that terminal and the machine it is directly connected + to.</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Local_Modes"><a class="permalink" href="#Local_Modes">Local + Modes</a></h2> +<p class="Pp">Values of the <var class="Fa">c_lflag</var> field describe the + control of various functions, and are composed of the following masks.</p> +<p class="Pp"></p> +<div class="Bd-indent"> +<dl class="Bl-tag Bl-compact"> + <dt id="ECHOKE"><a class="permalink" href="#ECHOKE"><code class="Dv">ECHOKE</code></a></dt> + <dd>/* visual erase for line kill */</dd> + <dt id="ECHOE"><a class="permalink" href="#ECHOE"><code class="Dv">ECHOE</code></a></dt> + <dd>/* visually erase chars */</dd> + <dt id="ECHO"><a class="permalink" href="#ECHO"><code class="Dv">ECHO</code></a></dt> + <dd>/* enable echoing */</dd> + <dt id="ECHONL"><a class="permalink" href="#ECHONL"><code class="Dv">ECHONL</code></a></dt> + <dd>/* echo <code class="Dv">NL</code> even if <code class="Dv">ECHO</code> is + off */</dd> + <dt id="ECHOPRT"><a class="permalink" href="#ECHOPRT"><code class="Dv">ECHOPRT</code></a></dt> + <dd>/* visual erase mode for hardcopy */</dd> + <dt id="ECHOCTL"><a class="permalink" href="#ECHOCTL"><code class="Dv">ECHOCTL</code></a></dt> + <dd>/* echo control chars as ^(Char) */</dd> + <dt id="ISIG"><a class="permalink" href="#ISIG"><code class="Dv">ISIG</code></a></dt> + <dd>/* enable signals <code class="Dv">INTR</code>, + <code class="Dv">QUIT</code>, <code class="Dv">[D]SUSP</code> */</dd> + <dt id="ICANON"><a class="permalink" href="#ICANON"><code class="Dv">ICANON</code></a></dt> + <dd>/* canonicalize input lines */</dd> + <dt id="ALTWERASE"><a class="permalink" href="#ALTWERASE"><code class="Dv">ALTWERASE</code></a></dt> + <dd>/* use alternative <code class="Dv">WERASE</code> algorithm */</dd> + <dt id="IEXTEN"><a class="permalink" href="#IEXTEN"><code class="Dv">IEXTEN</code></a></dt> + <dd>/* enable <code class="Dv">DISCARD</code> and + <code class="Dv">LNEXT</code> */</dd> + <dt id="EXTPROC"><a class="permalink" href="#EXTPROC"><code class="Dv">EXTPROC</code></a></dt> + <dd>/* external processing */</dd> + <dt id="TOSTOP"><a class="permalink" href="#TOSTOP"><code class="Dv">TOSTOP</code></a></dt> + <dd>/* stop background jobs from output */</dd> + <dt id="FLUSHO"><a class="permalink" href="#FLUSHO"><code class="Dv">FLUSHO</code></a></dt> + <dd>/* output being flushed (state) */</dd> + <dt id="NOKERNINFO"><a class="permalink" href="#NOKERNINFO"><code class="Dv">NOKERNINFO</code></a></dt> + <dd>/* no kernel output from <code class="Dv">VSTATUS</code> */</dd> + <dt id="PENDIN"><a class="permalink" href="#PENDIN"><code class="Dv">PENDIN</code></a></dt> + <dd>/* re-echo input buffer at next read */</dd> + <dt id="NOFLSH"><a class="permalink" href="#NOFLSH"><code class="Dv">NOFLSH</code></a></dt> + <dd>/* don't flush output on signal */</dd> +</dl> +</div> +<p class="Pp">If <code class="Dv">ECHO</code> is set, input characters are + echoed back to the terminal. If <code class="Dv">ECHO</code> is not set, + input characters are not echoed.</p> +<p class="Pp">If <code class="Dv">ECHOE</code> and + <code class="Dv">ICANON</code> are set, the <code class="Dv">ERASE</code> + character causes the terminal to erase the last character in the current + line from the display, if possible. If there is no character to erase, an + implementation may echo an indication that this was the case or do + nothing.</p> +<p class="Pp">If <code class="Dv">ECHOK</code> and + <code class="Dv">ICANON</code> are set, the <code class="Dv">KILL</code> + character causes the current line to be discarded and the system echoes the + ‘<code class="Li">\n</code>’ character after the + <code class="Dv">KILL</code> character.</p> +<p class="Pp">If <code class="Dv">ECHOKE</code> and + <code class="Dv">ICANON</code> are set, the <code class="Dv">KILL</code> + character causes the current line to be discarded and the system causes the + terminal to erase the line from the display.</p> +<p class="Pp">If <code class="Dv">ECHOPRT</code> and + <code class="Dv">ICANON</code> are set, the system assumes that the display + is a printing device and prints a backslash and the erased characters when + processing <code class="Dv">ERASE</code> characters, followed by a forward + slash.</p> +<p class="Pp">If <code class="Dv">ECHOCTL</code> is set, the system echoes + control characters in a visible fashion using a caret followed by the + control character.</p> +<p class="Pp">If <code class="Dv">ALTWERASE</code> is set, the system uses an + alternative algorithm for determining what constitutes a word when + processing <code class="Dv">WERASE</code> characters (see + <code class="Dv">WERASE</code>).</p> +<p class="Pp">If <code class="Dv">ECHONL</code> and + <code class="Dv">ICANON</code> are set, the + ‘<code class="Li">\n</code>’ character echoes even if + <code class="Dv">ECHO</code> is not set.</p> +<p class="Pp">If <code class="Dv">ICANON</code> is set, canonical processing is + enabled. This enables the erase and kill edit functions, and the assembly of + input characters into lines delimited by <code class="Dv">NL</code>, + <code class="Dv">EOF</code>, and <code class="Dv">EOL</code>, as described + in <a class="Sx" href="#Canonical_Mode_Input_Processing">Canonical Mode + Input Processing</a>.</p> +<p class="Pp">If <code class="Dv">ICANON</code> is not set, read requests are + satisfied directly from the input queue. A read is not satisfied until at + least <code class="Dv">VMIN</code> bytes have been received or the timeout + value <code class="Dv">VTIME</code> expired between bytes. The time value + represents tenths of seconds. See + <a class="Sx" href="#Noncanonical_Mode_Input_Processing">Noncanonical Mode + Input Processing</a> for more details.</p> +<p class="Pp">If <code class="Dv">ISIG</code> is set, each input character is + checked against the special control characters <code class="Dv">INTR</code>, + <code class="Dv">QUIT</code>, and <code class="Dv">SUSP</code> (job control + only). If an input character matches one of these control characters, the + function associated with that character is performed. If + <code class="Dv">ISIG</code> is not set, no checking is done. Thus these + special input functions are possible only if <code class="Dv">ISIG</code> is + set.</p> +<p class="Pp">If <code class="Dv">IEXTEN</code> is set, implementation-defined + functions are recognized from the input data. How + <code class="Dv">IEXTEN</code> being set interacts with + <code class="Dv">ICANON</code>, <code class="Dv">ISIG</code>, + <code class="Dv">IXON</code>, or <code class="Dv">IXOFF</code> is + implementation defined. If <code class="Dv">IEXTEN</code> is not set, then + implementation-defined functions are not recognized, and the corresponding + input characters are not processed as described for + <code class="Dv">ICANON</code>, <code class="Dv">ISIG</code>, + <code class="Dv">IXON</code>, and <code class="Dv">IXOFF</code>.</p> +<p class="Pp">If <code class="Dv">NOFLSH</code> is set, the normal flush of the + input and output queues associated with the <code class="Dv">INTR</code>, + <code class="Dv">QUIT</code>, and <code class="Dv">SUSP</code> characters + are not be done.</p> +<p class="Pp">If <code class="Dv">TOSTOP</code> is set, the signal + <code class="Dv">SIGTTOU</code> is sent to the process group of a process + that tries to write to its controlling terminal if it is not in the + foreground process group for that terminal. This signal, by default, stops + the members of the process group. Otherwise, the output generated by that + process is output to the current output stream. Processes that are blocking + or ignoring <code class="Dv">SIGTTOU</code> signals are excepted and allowed + to produce output and the <code class="Dv">SIGTTOU</code> signal is not + sent.</p> +<p class="Pp">If <code class="Dv">NOKERNINFO</code> is set, the kernel does not + produce a status message when processing <code class="Dv">STATUS</code> + characters (see <code class="Dv">STATUS</code>).</p> +</section> +<section class="Ss"> +<h2 class="Ss" id="Special_Control_Characters"><a class="permalink" href="#Special_Control_Characters">Special + Control Characters</a></h2> +<p class="Pp">The special control characters values are defined by the array + <var class="Fa">c_cc</var>. This table lists the array index, the + corresponding special character, and the system default value. For an + accurate list of the system defaults, consult the header file + <code class="In"><<a class="In">ttydefaults.h</a>></code>.</p> +<p class="Pp"></p> +<table class="Bl-column Bd-indent Bl-compact"> + <tr id="Index"> + <td><a class="permalink" href="#Index"><i class="Em">Index Name</i></a></td> + <td>Special Character</td> + <td>Default Value</td> + </tr> + <tr id="VEOF"> + <td><a class="permalink" href="#VEOF"><code class="Dv">VEOF</code></a></td> + <td>EOF</td> + <td>^D</td> + </tr> + <tr id="VEOL"> + <td><a class="permalink" href="#VEOL"><code class="Dv">VEOL</code></a></td> + <td>EOL</td> + <td>_POSIX_VDISABLE</td> + </tr> + <tr id="VEOL2"> + <td><a class="permalink" href="#VEOL2"><code class="Dv">VEOL2</code></a></td> + <td>EOL2</td> + <td>_POSIX_VDISABLE</td> + </tr> + <tr id="VERASE"> + <td><a class="permalink" href="#VERASE"><code class="Dv">VERASE</code></a></td> + <td>ERASE</td> + <td>^? ‘<code class="Li">\177</code>’</td> + </tr> + <tr id="VWERASE"> + <td><a class="permalink" href="#VWERASE"><code class="Dv">VWERASE</code></a></td> + <td>WERASE</td> + <td>^W</td> + </tr> + <tr id="VKILL"> + <td><a class="permalink" href="#VKILL"><code class="Dv">VKILL</code></a></td> + <td>KILL</td> + <td>^U</td> + </tr> + <tr id="VREPRINT"> + <td><a class="permalink" href="#VREPRINT"><code class="Dv">VREPRINT</code></a></td> + <td>REPRINT</td> + <td>^R</td> + </tr> + <tr id="VINTR"> + <td><a class="permalink" href="#VINTR"><code class="Dv">VINTR</code></a></td> + <td>INTR</td> + <td>^C</td> + </tr> + <tr id="VQUIT"> + <td><a class="permalink" href="#VQUIT"><code class="Dv">VQUIT</code></a></td> + <td>QUIT</td> + <td>^\\ ‘<code class="Li">\34</code>’</td> + </tr> + <tr id="VSUSP"> + <td><a class="permalink" href="#VSUSP"><code class="Dv">VSUSP</code></a></td> + <td>SUSP</td> + <td>^Z</td> + </tr> + <tr id="VDSUSP"> + <td><a class="permalink" href="#VDSUSP"><code class="Dv">VDSUSP</code></a></td> + <td>DSUSP</td> + <td>^Y</td> + </tr> + <tr id="VSTART"> + <td><a class="permalink" href="#VSTART"><code class="Dv">VSTART</code></a></td> + <td>START</td> + <td>^Q</td> + </tr> + <tr id="VSTOP"> + <td><a class="permalink" href="#VSTOP"><code class="Dv">VSTOP</code></a></td> + <td>STOP</td> + <td>^S</td> + </tr> + <tr id="VLNEXT"> + <td><a class="permalink" href="#VLNEXT"><code class="Dv">VLNEXT</code></a></td> + <td>LNEXT</td> + <td>^V</td> + </tr> + <tr id="VDISCARD"> + <td><a class="permalink" href="#VDISCARD"><code class="Dv">VDISCARD</code></a></td> + <td>DISCARD</td> + <td>^O</td> + </tr> + <tr id="VMIN"> + <td><a class="permalink" href="#VMIN"><code class="Dv">VMIN</code></a></td> + <td>---</td> + <td>1</td> + </tr> + <tr id="VTIME"> + <td><a class="permalink" href="#VTIME"><code class="Dv">VTIME</code></a></td> + <td>---</td> + <td>0</td> + </tr> + <tr id="VSTATUS"> + <td><a class="permalink" href="#VSTATUS"><code class="Dv">VSTATUS</code></a></td> + <td>STATUS</td> + <td>^T</td> + </tr> +</table> +<p class="Pp">If the value of one of the changeable special control characters + (see <a class="Sx" href="#Special_Characters">Special Characters</a>) is + {<code class="Dv">_POSIX_VDISABLE</code>}, that function is disabled; that + is, no input data is recognized as the disabled special character. If + <code class="Dv">ICANON</code> is not set, the value of + {<code class="Dv">_POSIX_VDISABLE</code>} has no special meaning for the + <code class="Dv">VMIN</code> and <code class="Dv">VTIME</code> entries of + the <var class="Fa">c_cc</var> array.</p> +<p class="Pp">The initial values of the flags and control characters after + <a class="Xr">open(2)</a> is set according to the values in the header + <code class="In"><<a class="In">sys/ttydefaults.h</a>></code>.</p> +</section> +</section> +<section class="Sh"> +<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE + ALSO</a></h1> +<p class="Pp"><a class="Xr">tcsendbreak(3)</a>, + <a class="Xr">tcsetattr(3)</a></p> +</section> +</div> +<table class="foot"> + <tr> + <td class="foot-date">October 7, 2006</td> + <td class="foot-os">NetBSD 10.1</td> + </tr> +</table> |