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| <H2><A NAME="s10">10. The keyboard LEDs</A></H2> |
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| <P> |
| <!-- |
| LEDs, keyboard |
| --> |
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| <!-- |
| keyboard!LEDs on |
| --> |
| <P>1. There are per-tty keyboard flags: |
| each VC has its own NumLock, CapsLock, ScrollLock. |
| By default these keyboard flags are shown in the LEDs. |
| The usual way to change them is by pressing the corresponding key. |
| (Side remark: pressing the NumLock key when in application key mode |
| will not change the NumLock status, but produce an escape sequence. |
| If you want the NumLock key to always change the Numlock status, |
| bind it to Bare_Num_Lock.) |
| <P>2. Next, there are per-tty default keyboard flags, |
| to initialize the keyboard flags when a reset occurs. |
| Thus if you want NumLock on all the time, that is possible. |
| The usual way to change them is by `<CODE>setleds -D</CODE> ...'. |
| <P>3. There is the possibility that the leds do not reflect |
| the keyboard flags, but something else. |
| <P>3A. This something else can be three bits somewhere in the kernel - |
| which can be used if you want to monitor some hardware or software |
| status bit(s). If you want this, edit the kernel source to call |
| <CODE>register_leds()</CODE> somewhere. |
| <P>3B. This something else can also be whatever some user program wants |
| to show in the LEDs. Thus, people who like such things can make |
| nice patterns of lights. If you want this, use the KDSETLED ioctl. |
| <P>This latter use is not per-tty, but the choice between former |
| and latter use is per-tty. |
| <P>Summarizing: Each tty has a flag <CODE>kbd->ledmode</CODE>. |
| If this has the value LED_SHOW_FLAGS then the keyboard flags |
| (NumLock etc.) of that tty are shown. |
| If this has the value LED_SHOW_MEM then three selected memory |
| addresses are shown. |
| If this has the value LED_SHOW_IOCTL then the leds show whatever |
| value was last assigned to them using the KDSETLED ioctl. |
| <P>One may add that X uses ioctl's to set the LEDs, but fails |
| to reset its VT when it exits, so after using X there may |
| be one VT that is not in the default LED_SHOW_FLAGS state. |
| This can be fixed by doing `<CODE>setleds -L</CODE>' on that VT. |
| See setleds(1). |
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