No, essentially your program is REPLACING the login prompt. Instead of the login program running on tty1, your Perl program will start; the keyboard (wedge) will go to the Perl program's stdin, and stdout will go to that virtual screen. If you did ever connect a screen to that Pi, the output of your program is what would be displayed there.
On Mon, Aug 31, 2015 at 1:55 PM, Curt Lundgren <[email protected]> wrote: > My specific worry is will the program (Perl) be hit with a login prompt? I > was thinking if that's the case I could use a couple of reject cards, > misprints, etc. as user name and password. Tap one, then the other to get > logged in. Am I overthinking this? > > On Mon, Aug 31, 2015 at 1:53 PM, Tilghman Lesher <[email protected]> > wrote: >> >> What language is your current program written in? >> >> It should work being invoked from init, although how init invokes it >> is different based upon which init program is running on the system. >> On Ubuntu 12.04, the file to edit is /etc/init/tty1.conf. Once it's >> running, just read from STDIN. >> >> On Mon, Aug 31, 2015 at 1:47 PM, Curt Lundgren <[email protected]> wrote: >> > It's a generic USB reader for Mifare 1K Classic cards. The reader puts >> > out >> > a 13.5 MHz field which is picked up by a few turns of wire embedded in >> > the >> > card. The field provides power to the chip, which can then do >> > bidirectional >> > communication with the reader. This is a simple reader that only grabs >> > the >> > CSN, card serial number. It's a 32-bit code which this reader gives me >> > as 8 >> > hexadecimal digits. The range of the card/reader is about 1-1/2" so a >> > 'tap' >> > of the card on the reader yields a solid read every time. >> > >> > It's HID, so it outputs 'scan codes' as detailed above. Tilghman offers >> > an >> > interesting approach, still not quite sure how I'd go about that. >> > >> > If these were Hollerith cards, you'd have to call me Hangin' Chad… >> > >> > On Mon, Aug 31, 2015 at 1:24 PM, Jack Coats <[email protected]> wrote: >> >> >> >> I am to old... I thought you were talking 80 or (the smaller) 96 column >> >> cards! ... Many of those readers put out EBCDIC instead of ASCII. >> >> But as always, I digress into ancient history when mainframes roamed >> >> the >> >> earth. >> >> >> >> Now that I am past the 20th century in my thinking, what flavor of card >> >> reader are you using? How is it connected? >> >> >> >> On Sun, Aug 30, 2015 at 8:19 PM, Tilghman Lesher <[email protected]> >> >> wrote: >> >>> >> >>> Sounds like what you're talking about is that the device is acting as >> >>> a keyboard wedge -- that is, it's inserting a stream of characters >> >>> into the keyboard buffer, probably through its device driver. I have >> >>> a magnetic card reader here that works in precisely the same way. >> >>> >> >>> The long and short of it is that your program would need to be running >> >>> in the foreground; that is, having its stdin being supplied by the >> >>> console. Probably the best way to do this in Linux on boot would be >> >>> to have your program run directly from init, associated with tty1, NOT >> >>> background itself, and as long as the machine stays on that terminal >> >>> device (and it should), your program should get all keyboard input >> >>> directly from stdin (fd 0). >> >>> >> >>> >> >>> On Sun, Aug 30, 2015 at 8:01 PM, Curt Lundgren <[email protected]> >> >>> wrote: >> >>> > I'm working on a program for a Raspberry Pi (one of the cool new >> >>> > ones >> >>> > with >> >>> > the quad-core CPU and a gigabyte of RAM). The program will run as a >> >>> > daemon >> >>> > and this unit is headless - there's no keyboard plugged in. Just a >> >>> > USB >> >>> > Mifare HID card reader that outputs 8 hex characters when a card is >> >>> > in >> >>> > proximity, then an 'Enter.' >> >>> > >> >>> > It's actually outputting scan codes, but I figure I can convert them >> >>> > to >> >>> > the >> >>> > appropriate hex codes. >> >>> > >> >>> > I understand if I was running on the console, tapping a card on the >> >>> > reader >> >>> > would cause the hex string to be input wherever my cursor is. I'd >> >>> > love >> >>> > to >> >>> > be able to redirect that input to my program, but I'm clueless on >> >>> > how >> >>> > that's >> >>> > done. My google-fu isn't working for me here either. >> >>> > >> >>> > The card reader does show up as /dev/input/event0 and if I cat that, >> >>> > it >> >>> > outputs a bunch of binary stuff. I can send it to a file and a hex >> >>> > dump of >> >>> > part of that file looks like this: >> >>> > >> >>> > 00000000: eba1 e355 6032 0600 0400 0400 2700 0700 ...U`2......'... >> >>> > 00000010: eba1 e355 6032 0600 0100 0b00 0100 0000 ...U`2.......... >> >>> > 00000020: eba1 e355 6032 0600 0000 0000 0000 0000 ...U`2.......... >> >>> > 00000030: eba1 e355 7251 0600 0400 0400 2700 0700 ...UrQ......'... >> >>> > 00000040: eba1 e355 7251 0600 0100 0b00 0000 0000 ...UrQ.......... >> >>> > 00000050: eba1 e355 7251 0600 0000 0000 0000 0000 ...UrQ.......... >> >>> > 00000060: eba1 e355 ad70 0600 0400 0400 1f00 0700 ...U.p.......... >> >>> > 00000070: eba1 e355 ad70 0600 0100 0300 0100 0000 ...U.p.......... >> >>> > 00000080: eba1 e355 ad70 0600 0000 0000 0000 0000 ...U.p.......... >> >>> > 00000090: eba1 e355 e48f 0600 0400 0400 1f00 0700 ...U............ >> >>> > 000000a0: eba1 e355 e48f 0600 0100 0300 0000 0000 ...U............ >> >>> > 000000b0: eba1 e355 e48f 0600 0000 0000 0000 0000 ...U............ >> >>> > 000000c0: eba1 e355 26af 0600 0400 0400 2400 0700 ...U&.......$... >> >>> > 000000d0: eba1 e355 26af 0600 0100 0800 0100 0000 ...U&........... >> >>> > 000000e0: eba1 e355 26af 0600 0000 0000 0000 0000 ...U&........... >> >>> > 000000f0: eba1 e355 64ce 0600 0400 0400 2400 0700 ...Ud.......$... >> >>> > 00000100: eba1 e355 64ce 0600 0100 0800 0000 0000 ...Ud........... >> >>> > 00000110: eba1 e355 64ce 0600 0000 0000 0000 0000 ...Ud........... >> >>> > >> >>> > Don't know if the formatting will display properly, but I've bolded >> >>> > a >> >>> > few >> >>> > bytes. The 0x27 is '0' and we see keypress and key release. This >> >>> > is >> >>> > followed by 0x1F (2) and 0x24 (7) - we march through the rest of the >> >>> > string >> >>> > and finally arrive at the 0x28 Enter key: >> >>> > >> >>> > 00000300: eba1 e355 3626 0800 0400 0400 2800 0700 ...U6&......(... >> >>> > 00000310: eba1 e355 3626 0800 0100 1c00 0100 0000 ...U6&.......... >> >>> > 00000320: eba1 e355 3626 0800 0000 0000 0000 0000 ...U6&.......... >> >>> > 00000330: eba1 e355 9145 0800 0400 0400 2800 0700 ...U.E......(... >> >>> > 00000340: eba1 e355 9145 0800 0100 1c00 0000 0000 ...U.E.......... >> >>> > 00000350: eba1 e355 9145 0800 0000 0000 0000 0000 ...U.E.......... >> >>> > >> >>> > I don't pretend to understand scan codes, but 48 bytes for keypress >> >>> > and >> >>> > another 48 for key release? Seems excessive, but it can be handled. >> >>> > The >> >>> > hex 0x01 below the scan code is keypress, the 0x00 below the other >> >>> > scan >> >>> > codes is key release. >> >>> > >> >>> > Questions: Can this data be grabbed from some convenient place in >> >>> > the >> >>> > OS, >> >>> > preferably as a nice 8-character string? What does the OS do with >> >>> > HID >> >>> > input >> >>> > when the Pi is running headless? The current plan says there will >> >>> > never be >> >>> > a real keyboard plugged in, just the card reader. >> >>> > >> >>> > Does anyone know what Linux does with input from an HID device when >> >>> > there's >> >>> > no session running from the console? Does it get intercepted by a >> >>> > login >> >>> > screen? >> >>> > >> >>> > OS is Raspbian Wheezy, apparently version 7 on a 3.18.11 kernel. >> >>> > >> >>> > TIA >> >>> > >> >>> > Curt >> >>> > >> >>> > -- >> >>> > -- >> >>> > You received this message because you are subscribed to the Google >> >>> > Groups >> >>> > "NLUG" group. >> >>> > To post to this group, send email to [email protected] >> >>> > To unsubscribe from this group, send email to >> >>> > [email protected] >> >>> > For more options, visit this group at >> >>> > http://groups.google.com/group/nlug-talk?hl=en >> >>> > >> >>> > --- >> >>> > You received this message because you are subscribed to the Google >> >>> > Groups >> >>> > "NLUG" group. >> >>> > To unsubscribe from this group and stop receiving emails from it, >> >>> > send >> >>> > an >> >>> > email to [email protected]. >> >>> > For more options, visit https://groups.google.com/d/optout. >> >>> >> >>> >> >>> >> >>> -- >> >>> Tilghman >> >>> >> >>> -- >> >>> -- >> >>> You received this message because you are subscribed to the Google >> >>> Groups >> >>> "NLUG" group. >> >>> To post to this group, send email to [email protected] >> >>> To unsubscribe from this group, send email to >> >>> [email protected] >> >>> For more options, visit this group at >> >>> http://groups.google.com/group/nlug-talk?hl=en >> >>> >> >>> --- >> >>> You received this message because you are subscribed to the Google >> >>> Groups >> >>> "NLUG" group. >> >>> To unsubscribe from this group and stop receiving emails from it, send >> >>> an >> >>> email to [email protected]. >> >>> For more options, visit https://groups.google.com/d/optout. >> >> >> >> >> >> >> >> >> >> -- >> >> ><> ... Jack >> >> >> >> The Four Boxes of Liberty - "There are four boxes to be used in the >> >> defense of liberty: soap, ballot, jury and ammo. Please use in that >> >> order." >> >> "Whatever you do, work at it with all your heart"... Colossians 3:23 >> >> "Anyone who has never made a mistake, has never tried anything new." - >> >> Albert Einstein >> >> "You don't manage people; you manage things. You lead people." - >> >> Admiral >> >> Grace Hopper, USN >> >> "Tell me and I forget. Teach me and I remember. Involve me and I >> >> learn." - >> >> Ben Franklin >> >> >> >> -- >> >> -- >> >> You received this message because you are subscribed to the Google >> >> Groups >> >> "NLUG" group. >> >> To post to this group, send email to [email protected] >> >> To unsubscribe from this group, send email to >> >> [email protected] >> >> For more options, visit this group at >> >> http://groups.google.com/group/nlug-talk?hl=en >> >> >> >> --- >> >> You received this message because you are subscribed to the Google >> >> Groups >> >> "NLUG" group. >> >> To unsubscribe from this group and stop receiving emails from it, send >> >> an >> >> email to [email protected]. >> >> For more options, visit https://groups.google.com/d/optout. >> > >> > >> > -- >> > -- >> > You received this message because you are subscribed to the Google >> > Groups >> > "NLUG" group. >> > To post to this group, send email to [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> > http://groups.google.com/group/nlug-talk?hl=en >> > >> > --- >> > You received this message because you are subscribed to the Google >> > Groups >> > "NLUG" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> > an >> > email to [email protected]. >> > For more options, visit https://groups.google.com/d/optout. >> >> >> >> -- >> Tilghman >> >> -- >> -- >> You received this message because you are subscribed to the Google Groups >> "NLUG" group. >> To post to this group, send email to [email protected] >> To unsubscribe from this group, send email to >> [email protected] >> For more options, visit this group at >> http://groups.google.com/group/nlug-talk?hl=en >> >> --- >> You received this message because you are subscribed to the Google Groups >> "NLUG" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. > > > -- > -- > You received this message because you are subscribed to the Google Groups > "NLUG" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/nlug-talk?hl=en > > --- > You received this message because you are subscribed to the Google Groups > "NLUG" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. -- Tilghman -- -- You received this message because you are subscribed to the Google Groups "NLUG" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nlug-talk?hl=en --- You received this message because you are subscribed to the Google Groups "NLUG" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
