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.
