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| |
| <h4 class="subsection">17.4.7 Local Modes</h4> |
| |
| <p>This section describes the flags for the <code>c_lflag</code> member of the |
| <code>struct termios</code> structure. These flags generally control |
| higher-level aspects of input processing than the input modes flags |
| described in <a href="Input-Modes.html#Input-Modes">Input Modes</a>, such as echoing, signals, and the choice |
| of canonical or noncanonical input. |
| |
| <p>The <code>c_lflag</code> member itself is an integer, and you change the flags |
| and fields using the operators <code>&</code>, <code>|</code>, and <code>^</code>. Don't |
| try to specify the entire value for <code>c_lflag</code>—instead, change |
| only specific flags and leave the rest untouched (see <a href="Setting-Modes.html#Setting-Modes">Setting Modes</a>). |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ICANON</b><var><a name="index-ICANON-1906"></a></var><br> |
| <blockquote><p>This bit, if set, enables canonical input processing mode. Otherwise, |
| input is processed in noncanonical mode. See <a href="Canonical-or-Not.html#Canonical-or-Not">Canonical or Not</a>. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHO</b><var><a name="index-ECHO-1907"></a></var><br> |
| <blockquote><p>If this bit is set, echoing of input characters back to the terminal |
| is enabled. |
| <a name="index-echo-of-terminal-input-1908"></a></p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHOE</b><var><a name="index-ECHOE-1909"></a></var><br> |
| <blockquote><p>If this bit is set, echoing indicates erasure of input with the ERASE |
| character by erasing the last character in the current line from the |
| screen. Otherwise, the character erased is re-echoed to show what has |
| happened (suitable for a printing terminal). |
| |
| <p>This bit only controls the display behavior; the <code>ICANON</code> bit by |
| itself controls actual recognition of the ERASE character and erasure of |
| input, without which <code>ECHOE</code> is simply irrelevant. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHOPRT</b><var><a name="index-ECHOPRT-1910"></a></var><br> |
| <blockquote><p>This bit is like <code>ECHOE</code>, enables display of the ERASE character in |
| a way that is geared to a hardcopy terminal. When you type the ERASE |
| character, a ‘<samp><span class="samp">\</span></samp>’ character is printed followed by the first |
| character erased. Typing the ERASE character again just prints the next |
| character erased. Then, the next time you type a normal character, a |
| ‘<samp><span class="samp">/</span></samp>’ character is printed before the character echoes. |
| |
| <p>This is a BSD extension, and exists only in BSD systems and the |
| GNU system. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHOK</b><var><a name="index-ECHOK-1911"></a></var><br> |
| <blockquote><p>This bit enables special display of the KILL character by moving to a |
| new line after echoing the KILL character normally. The behavior of |
| <code>ECHOKE</code> (below) is nicer to look at. |
| |
| <p>If this bit is not set, the KILL character echoes just as it would if it |
| were not the KILL character. Then it is up to the user to remember that |
| the KILL character has erased the preceding input; there is no |
| indication of this on the screen. |
| |
| <p>This bit only controls the display behavior; the <code>ICANON</code> bit by |
| itself controls actual recognition of the KILL character and erasure of |
| input, without which <code>ECHOK</code> is simply irrelevant. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHOKE</b><var><a name="index-ECHOKE-1912"></a></var><br> |
| <blockquote><p>This bit is similar to <code>ECHOK</code>. It enables special display of the |
| KILL character by erasing on the screen the entire line that has been |
| killed. This is a BSD extension, and exists only in BSD systems and the |
| GNU system. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHONL</b><var><a name="index-ECHONL-1913"></a></var><br> |
| <blockquote><p>If this bit is set and the <code>ICANON</code> bit is also set, then the |
| newline (<code>'\n'</code>) character is echoed even if the <code>ECHO</code> bit |
| is not set. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ECHOCTL</b><var><a name="index-ECHOCTL-1914"></a></var><br> |
| <blockquote><p>If this bit is set and the <code>ECHO</code> bit is also set, echo control |
| characters with ‘<samp><span class="samp">^</span></samp>’ followed by the corresponding text character. |
| Thus, control-A echoes as ‘<samp><span class="samp">^A</span></samp>’. This is usually the preferred mode |
| for interactive input, because echoing a control character back to the |
| terminal could have some undesired effect on the terminal. |
| |
| <p>This is a BSD extension, and exists only in BSD systems and the |
| GNU system. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ISIG</b><var><a name="index-ISIG-1915"></a></var><br> |
| <blockquote><p>This bit controls whether the INTR, QUIT, and SUSP characters are |
| recognized. The functions associated with these characters are performed |
| if and only if this bit is set. Being in canonical or noncanonical |
| input mode has no affect on the interpretation of these characters. |
| |
| <p>You should use caution when disabling recognition of these characters. |
| Programs that cannot be interrupted interactively are very |
| user-unfriendly. If you clear this bit, your program should provide |
| some alternate interface that allows the user to interactively send the |
| signals associated with these characters, or to escape from the program. |
| <a name="index-interactive-signals_002c-from-terminal-1916"></a> |
| See <a href="Signal-Characters.html#Signal-Characters">Signal Characters</a>. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>IEXTEN</b><var><a name="index-IEXTEN-1917"></a></var><br> |
| <blockquote><p>POSIX.1 gives <code>IEXTEN</code> implementation-defined meaning, |
| so you cannot rely on this interpretation on all systems. |
| |
| <p>On BSD systems and the GNU system, it enables the LNEXT and DISCARD characters. |
| See <a href="Other-Special.html#Other-Special">Other Special</a>. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>NOFLSH</b><var><a name="index-NOFLSH-1918"></a></var><br> |
| <blockquote><p>Normally, the INTR, QUIT, and SUSP characters cause input and output |
| queues for the terminal to be cleared. If this bit is set, the queues |
| are not cleared. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>TOSTOP</b><var><a name="index-TOSTOP-1919"></a></var><br> |
| <blockquote><p>If this bit is set and the system supports job control, then |
| <code>SIGTTOU</code> signals are generated by background processes that |
| attempt to write to the terminal. See <a href="Access-to-the-Terminal.html#Access-to-the-Terminal">Access to the Terminal</a>. |
| </p></blockquote></div> |
| |
| <p>The following bits are BSD extensions; they exist only in BSD systems |
| and the GNU system. |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>ALTWERASE</b><var><a name="index-ALTWERASE-1920"></a></var><br> |
| <blockquote><p>This bit determines how far the WERASE character should erase. The |
| WERASE character erases back to the beginning of a word; the question |
| is, where do words begin? |
| |
| <p>If this bit is clear, then the beginning of a word is a nonwhitespace |
| character following a whitespace character. If the bit is set, then the |
| beginning of a word is an alphanumeric character or underscore following |
| a character which is none of those. |
| |
| <p>See <a href="Editing-Characters.html#Editing-Characters">Editing Characters</a>, for more information about the WERASE character. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>FLUSHO</b><var><a name="index-FLUSHO-1921"></a></var><br> |
| <blockquote><p>This is the bit that toggles when the user types the DISCARD character. |
| While this bit is set, all output is discarded. See <a href="Other-Special.html#Other-Special">Other Special</a>. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>NOKERNINFO</b><var><a name="index-NOKERNINFO-1922"></a></var><br> |
| <blockquote><p>Setting this bit disables handling of the STATUS character. |
| See <a href="Other-Special.html#Other-Special">Other Special</a>. |
| </p></blockquote></div> |
| |
| <!-- termios.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: tcflag_t <b>PENDIN</b><var><a name="index-PENDIN-1923"></a></var><br> |
| <blockquote><p>If this bit is set, it indicates that there is a line of input that |
| needs to be reprinted. Typing the REPRINT character sets this bit; the |
| bit remains set until reprinting is finished. See <a href="Editing-Characters.html#Editing-Characters">Editing Characters</a>. |
| </p></blockquote></div> |
| |
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