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linuxdebianraspbian

Modify Debian image for raspberry pi

I need to modify a Raspbian image for use with Raspberry Pi's in a commercial setting. This way I won't have to modify the defaults of every single pi afterwards. I want to set the default keyboard to U.S., disable auto-login and boot to command line rather than GUI. Is it possible to modify an image with these settings before flashing each card? If so, how?

Solution

  • The easiest approach would be to get one Raspi behaving the exact way you want (called a golden master), then shut it down, pull the card, and do something similar to the following in your PC's SD card reader (from which I assume you baked the first card):

    sudo dd if=/dev/<sddevice> bs=1k | gzip -c > myProduct-1.0-master.bin.gz

    Then just bake that image onto card #2, #3...#n using:

    zcat myProduct-1.0-master.bin.gz | sudo dd of=/dev/<sddevice> bs=1k

    NB about card sizes: Always make sure your golden master card is SIGNIFICANTLY SMALLER than your target cards (ideally 2x, like 8-vs-16 GB). The reasons for this are twofold:

    • If both cards are "8GB," the target might be slightly smaller than the source (in which case you'll end up with filesystem truncation and possibly weirdness in subtle and unpredictable ways).
    • SD card controllers have EXTREMELY PRIMITIVE wear leveling and dd'ing over a bunch of zeroes defeats it utterly (which means cards can die if you're doing e.g. a bunch of logging). Keeping a bunch of unused space means that you have fallow cells that can be used by wear leveling (note that modern SSDs have much more sophisticated wear leveling and don't suffer from this problem for the most part).

    I created a product not too long ago that did just this--the master was an 8GB full-size card and the targets were all 16GB micros. We'd put the master in the mass duplicator, then the targets and hit the big duplicate button. Because the cards were different storage sizes, we had ~50% underprovisioning (giving us tons of wear-level room) and because the cards were different physical sizes, we never mixed them up :-)

    (Yes, I'm ridiculously conservative about wear-leveling--nothing worse IMO than having an embedded card die in the field and having to crawl through God-knows-what to replace a $8 part that didn't have to fail in the first place...)

    It's worth creating a VERSION file on your master, as well, so as you rev your product you know which version is installed (you can edit /etc/issue to display that at the login prompt, or just edit some other arbitrary text file).

    It's possible to create from-scratch images for the RasPi that have a more-tightly-controlled OS distro, but if you're only adjusting a couple of files, the easiest way is as I describe.

    Oh, and make sure to save these versioned images someplace safe, like git LFS (e.g. https://git-lfs.github.com/).