Here's a CLI version of the script, @Altoid I have not added the additional sleep command here, if you test it maybe try it as-is first, and then if it fails at the check, add sleep 1 on line 106, maybe sleep 2. It would be awesome if you could also just try using a regular usb stick plugged in to one of your machines original usb 2 ports.

#!/bin/bash

# Fatstick CLI: Creates a secondary FAT32 data partition on a liveUSB made with Mintstick.
# Copyleft greenjeans 2025, use as you see fit.
# This is free software with NO WARRANTY, use at your own risk!

# Function to display error message and exit
error_exit() {
    local error_message="$1"
    echo "Error: $error_message" >&2
    exit 1
}

# Must run with root privileges
if [ "$EUID" -ne 0 ]; then
    error_exit "This script must be run as root (use sudo or su)."
fi

# Display initial prompt
echo "This utility is for use on an existing liveUSB with an ISO-9660 filesystem"
echo "created by Mintstick. It will create a secondary FAT32 data partition labeled"
echo "'DATA' in the remaining space. WARNING: Existing secondary partitions will be"
echo "overwritten, and data on them will be lost."
echo ""
echo "Ensure only one liveUSB with an ISO-9660 filesystem is plugged in."
echo "Run 'lsblk -o NAME,FSTYPE,LABEL' or 'blkid' to check connected devices."
echo ""
echo "Continue? (y/n): "
read -r response
if [ "$response" != "y" ] && [ "$response" != "Y" ]; then
    echo "Aborted."
    exit 0
fi

# Check for multiple USBs with iso9660 filesystems
ISO_COUNT=$(blkid -o device -t TYPE=iso9660 | wc -l)
if [ "$ISO_COUNT" -gt 1 ]; then
    error_exit "Multiple USB devices with ISO-9660 filesystems detected. Unplug all but one and try again. Run 'blkid -o list' to identify devices."
elif [ "$ISO_COUNT" -eq 0 ]; then
    error_exit "No USB with ISO-9660 filesystem found. Run 'lsblk -o NAME,FSTYPE,LABEL' and 'blkid' to diagnose."
fi

# Find the USB device with an iso9660 filesystem
USB_PART=$(blkid -o device -t TYPE=iso9660 | head -n 1)
if [ -n "$USB_PART" ]; then
    USB_DEV=$(echo "$USB_PART" | sed 's/[0-9]*$//')
fi

# Fallback to lsblk if blkid fails
if [ -z "$USB_DEV" ]; then
    USB_PART=$(lsblk -o NAME,FSTYPE | grep iso9660 | awk '{print $1}' | head -n 1)
    USB_DEV=$(echo "$USB_PART" | sed 's/[0-9]*$//' | head -n 1)
    USB_DEV="/dev/${USB_DEV}"
fi

if [ -z "$USB_DEV" ] || [ ! -b "$USB_DEV" ]; then
    error_exit "No USB with ISO-9660 filesystem found. Run 'lsblk -o NAME,FSTYPE,LABEL' and 'blkid' to diagnose."
fi

# Unmount any mounted partitions on the USB
umount "${USB_DEV}"* 2>/dev/null

# Get the partition table and disk info
FDISK_OUT=$(fdisk -l "$USB_DEV" 2>/dev/null)
if [ -z "$FDISK_OUT" ]; then
    error_exit "Failed to read disk info with fdisk."
fi

# Extract the end sector of the iso9660 partition
ISO_END=$(echo "$FDISK_OUT" | grep "^${USB_PART}" | awk '{print $4}')
if [ -z "$ISO_END" ]; then
    error_exit "Could not determine end sector of iso9660 partition."
fi

# Extract total sectors
TOTAL_SECTORS=$(echo "$FDISK_OUT" | grep "^Disk $USB_DEV" | grep -o '[0-9]\+ sectors' | awk '{print $1}')
if [ -z "$TOTAL_SECTORS" ]; then
    error_exit "Could not determine total disk sectors."
fi

# Calculate start and size of the new partition
PART_START=$((ISO_END + 1))
PART_SIZE=$((TOTAL_SECTORS - PART_START))

# Check space (needs at least 1 MB = 2048 sectors)
if [ "$PART_SIZE" -lt 2048 ]; then
    error_exit "Not enough free space to create a new partition (need at least 1 MB)."
fi

# Proactively wipe ISO-9660 signatures to prevent Gparted detection issues
echo "Wiping ISO-9660 signatures..."
wipefs -a -t iso9660 "$USB_DEV" 2>/dev/null || {
    error_exit "Failed to wipe ISO-9660 signatures on $USB_DEV."
}

# Remove any existing secondary partitions
echo "Removing existing secondary partitions..."
sfdisk --delete "$USB_DEV" 2 2>/dev/null

# Create a new partition using sfdisk
echo "Creating new partition..."
echo "start=$PART_START, size=$PART_SIZE, type=c" | sfdisk --append "$USB_DEV"
if [ $? -ne 0 ]; then
    error_exit "Failed to create partition on $USB_DEV."
fi

# Check if the new partition was created
NEW_PART="${USB_DEV}2"
if [ ! -b "$NEW_PART" ]; then
    error_exit "Failed to create partition $NEW_PART."
fi

# Refresh the partition table and wait for kernel to recognize new partition
echo "Refreshing partition table..."
partprobe "$USB_DEV"
sleep 2
for i in {1..3}; do
    if [ -b "$NEW_PART" ]; then
        break
    fi
    sleep 1
done
if [ ! -b "$NEW_PART" ]; then
    error_exit "New partition $NEW_PART not detected by kernel."
fi

# Format the new partition as FAT32
echo "Formatting new partition as FAT32..."
mkfs.vfat -n "DATA" "$NEW_PART" 2>/dev/null
if [ $? -ne 0 ]; then
    error_exit "Failed to format $NEW_PART as FAT32."
fi

# Verification of FAT32, 3 tries
for i in {1..3}; do
    if blkid -o device -t TYPE=vfat | grep "$NEW_PART" >/dev/null; then
        break
    fi
    sleep 1
done

if ! blkid -o device -t TYPE=vfat | grep "$NEW_PART" >/dev/null; then
    error_exit "Could not verify FAT32 filesystem on $NEW_PART, but partition was created. Check with 'lsblk -o NAME,FSTYPE,LABEL'."
fi

# Display success message
echo "Success! New partition $NEW_PART created with FAT32 filesystem, labeled 'DATA'."

^^^I'm just going by what others have said, again I have no experience with Ventoy myself.

In point of fact i'm working on my own scripts to make a utility to burn iso's to sticks and create additional partitions, of all of them Refracta2usb is the most complete and works the best to do all the things. I'm working on something in between it and Mintstick in terms of functionality. It's tough messing with USB's sometimes, fine line between success and disaster when working with all the things necessary to make it happen.

Devuan is not compatible with Ventoy it seems, have a look at this thread, may be some help:

https://dev1galaxy.org/viewtopic.php?id=7092

Shame that laptop doesn't have an optical drive.

The Devuan net-install works just like the Debian, you can choose to only create a CLI-only iso if desired then install programs after installing/booting it, or at the software section you can choose to add a number of DE's including KDE, but i'm not sure that will give you a core-only KDE, probably installs the whole works, I know if you choose Mate it installs the whole Mate meta-package.

If I want just core stuff, I do the CLI-only, boot that up, then start apt'ing.

Have not used or tested Ventoy myself. You can likely dd the iso manually if you're comfortable using dd.

I use Mintstick typically, it seems to just work with everything so far. Refracta2usb also works great, offering options for multi-boot and persistence that Mintstick does not.

ETA: Welcome to Devuan! It might have some quirks being free of the curse of systemd, but it's well worth the effort in the end, simple and stable.

@golinux, I knew you'd chime in, you dislike that damn file as much as I do, lol. But unfortunately i've had to embrace it.

If it were not for that file, I wouldn't have found a nasty bug in the excalibur version of Mate/Caja that caused it to grow exponentially, causing me to file a bug report, that was actually acted upon immediately by upstream folks and subsequently fixed.

FYI though, I think Mate just likes to complain, even in stable daedalus it writes errors to that file constantly. Openbox is the only set-up so far i've been able to clear completely of errors. Openbox in a lot of ways is better than every DE out there.

For others reading, the name is a misnomer, yes errors get dropped there, but in normal use it simply catalogs events related to login, and then some subsequent operations also get cataloged in that file, if you don't have errors in operation then none get written.

Okay that's a funky set-up my friend, sd card in a USB 2 converter, plugged into a USB3 slot...That's definitely an edge case, surprised it worked at all.

How you got a USB 3.0 slot on a 2009 machine?

Edit: Really need some more testing, preferably some garden-variety testing using actual USB sticks.

C'mon ya'll, help a brother out, this may not be important to ya, but it increases my knowledge and skill level which I hope to leverage into making myself of more use to Devuan and the community in the years to come, so it will benefit you too as Devuan users.

Thanks for testing @Altoid!

Yeah I had similar errors myself multiple times when testing later versions of the script. And sometimes it would error, yet work perfectly.

if you notice there are already some "timeouts" in there that fixed this on my machine at least. That's great info you gave me, seems I may need to extend/add some time in those areas. The script does work fast, too fast it seems for some other parts of the system. Any chance I could get specs of the machine you tested it on?
ETA: Also, model and size of stick?

And yeah, the stick winds up unmounted at the end of the process, but should still show in your file-manager as being present, so you should be able to just click the new partition(s) to mount. Pretty much all of my testing thus far has been in Mate, I need to run some tests in my Openbox partitions (though it should be same result).

@RRQ: Thanks for weighing in on this, I need to study your post a bit and do some research, again, i'm a rookie at this, but blkid seems to work fine for that check, if there's no vfat partition on that stick it's going to error out as it should, which is all i'm after...but yeah it may actually be a superfluous check anyway, i'm working off the premise right now that "if there's anything that gets done, it probably needs an error check". Which is mainly actually for my benefit to make it easier and faster to de-bug, some stuff probably doesn't need to be in the final script I guess.

ETA: Just wanted to re-iterate, I REALLY appreciate any and all comments and testing and suggestions, they are immensely helpful and give me things to consider that I might have not thought about, you guys rock and although my brain hurts a bit right now i'm still having a lot of fun with this stuff.

Thanks for the info and links folks!

Looking like postmarketOS is working on such and is probably the best hope for the future, but not solid as yet.

In the meantime I guess @ks's advice is probably best to get them up and running.

We have done a mountain of work on this library, still trying to catalog all the volumes, and with the work we've been doing word has gotten out and we've had a lot of donations of books. Also a nice cash donation that we're using for new shelving as previously there were boxes and boxes of books just sitting in corners.

I'm assuming that the iPads will at least interface with a linux box in some way so as to be able to load different content from the library machine to the tablet?

To be clear, I still have my training wheels on when it comes to writing scripts. This utility is part of my own self-training regimen which is to start writing more complex scripts than my usual tiny ones, not to the level of full-blown apps, just small targeted helper-scripts that aim to fix one or more small challenges. I have a ton of such things on the back-burner that are not yet working, this script is the 2nd successful one.

I do recognize that, I have that saved in my script experiments file!

This thing is just a very niche app, an experiment as is most of what I mess with. Might be some useful code to run with the above to automagically spit out a liveUSB with a data partition. I don't know that i've ever seen a poll to ask about people's preferences about
liveUSB's, do most just make a simple one, or do most prefer a persistence partition as well or data like I usually do?

I do like a dedicated app that does one thing and does it really well, hard not to like 'em.

Do the whole liveUSB plus a data partition and do it in like 200 lines of code or less....awww.yeeahhh

Ahh, so lxpolkit. Was thinking about trying that in my Openbox stuff, but the mate-polkit dropped right in without any extra configging for the most part. I did have to go in and delete the current ~/.config/dconf/user file to stop some errors in .xsession-errors every time I used authentication, then re-boot but those are gone now, just the main complaint at the top now that mate-polkit can't find org.gnome.session-manager.whatever.hoo-ha.

I am using the xfce power-manager in the max versions, and whoa-boy does it ever like to complain that it can't find stuff. Does it do that in an xfce session?

Chatter for months is that Tint2 would be going bye-bye, but it's in the testing repo again, which makes me very happy.

It's Nitrogen, that's what I use, and you have to add it to the Openbox autostart menu to get a bg applied at login. There's several things that need to be added to autostart to make everything happen, Tint2 for one. I also start the authentication daemon that way.

Which brings me to another question, what's going to be the default authentication for Devuan going forward? Since policykit-1-gnome is deprecated and not in the testing repo.

I just switched today to using the mate-polkit and dropped gnome, seems to work fine since they're both just front-end authentication agents for polkitd. I guess the gnome version hasn't been maintained in like 10 years, so they are dropping it in trixie.

That's cool, did not know that! If it were me i'd still use obmenu-generator, you can make a really pretty menu with it.

So a vanilla Devuan Openbox version, I guess Openbox can use the current desktop-base for artwork? That may be a dumb question, but I haven't tried it myself, I run my own artwork in my projects.

And what file manager? PcmanFM s the classic choice, it's still available, and despite multiple attempts to drop development, it lingers on, lol, new version in excalibur is now gtk3. But it has that one big bug about how it handles thumbnailing and caching, doesn't seem like anybody is going to fix it anytime soon. I do have a nice script that bandaids it to work a LOT better.