I'm having an issue with my Pi shutting down shortly after booting. I can see the boot messages pass by on the screen, but they pass by too quickly for me to read. Is there anyway I can redirect the boot messages to a file where I can more carefully analyze them? Note that whatever is causing the Pi to shutdown appears to cause it to shutdown properly (halt is called), so there should hopefully be no file corruption when doing this.

I'm running the most recent version of Raspbian and using a B+

  • Assuming you have time you could try this from the commandline dmesg >> boot.txt. this will append the dmesg text to a boot.txt file in your current directory. A single arrow dmesg > boot.txt will replace what ever text is in the file. You can also just view the text with dmesg. What was the last change you made to the system, a cron job maybe, or a start up script? – Steve Robillard Jan 5 '15 at 4:00
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    I don't think I would've had time for that. Actually what the problem ended up being a hardware issue; I connected something to the wrong GPIO pin; I'm making a shutdown switch using Pin 7 and I connected it to pin 8 instead. – audiFanatic Jan 5 '15 at 5:48
  • Regardless, I'm gonna leave this question open because I believe it's something that's important for debugging purposes. – audiFanatic Jan 5 '15 at 5:49

A solution is to connect pins 6 (ground) and 8 (gpio 14 UART TX) via a 3V3 compatible USB serial dongle to another computer,

By default The boot messages are sent to the UART. The data is transmitted at 115200 bps, 8 data bits, no parity, 1 stop bit (115.2 8N1).

If you launch minicom or equivalent software on your computer you will then be able to view/save/scroll the boot messages. If you also connect pin 10 (gpio 15 UART RX) you will be able to login to the Pi.

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