GRML2USB(8)

📦
version 0.20.14 · 5 versions
, in ubuntu stonking

💖 GRML2USB — the grml2usb(8) manual, but make it make sense 💖

okay bestie, sit down, hydrate, because we're about to install Grml on a USB stick and it's gonna be so good. this is the grml2usb page from section 8 of the manual, and I'm translating the whole thing for you. no details skipped, fr fr. 🫶

✨ NAME ✨

grml2usb — install Grml ISO(s) on USB device for booting 🦋

🌸 SYNOPSIS 🌸

grml2usb [ options ] <ISO[s]> <device>
okay so, real talk, the Grml team does not take responsibility for loss of any data. so like. back up your stuff. I'm begging. 😭

👑 INTRODUCTION 👑

grml2usb installs Grml on a given partition of your USB device and makes it bootable. it's giving main character USB stick.

it also does multiboot ISO support, which lowkey slay: you can hand it several Grml ISOs on the command line all at once, and then at the bootprompt you get to pick which Grml flavour you wanna boot. iconic.

one thing though — the first ISO you list on the grml2usb command line becomes the default one. so that's the one that boots when you just hit enter at the bootprompt, or when you let the boot timeout run out. ⭐

💀 important!! by default a compatible master boot record (MBR) gets installed on the device (that's like /dev/sdX when you run grml2usb grml.iso /dev/sdX1), and syslinux is used as the default bootloader. want none of that? use the --skip-mbr option to avoid installing the default MBR. or, if you're running into problems with the default MBR, consider --syslinux-mbr instead. 🧚

💅 OPTIONS 💅

ISO[s] should be the path to one or multiple grml-ISOs and/or the path to the currently running live-system (being /run/live/medium).

the device either might be a device name like /dev/sdX1 or a directory. here's the vibe:

  • if you give it a device name, the device gets mounted automatically.
  • if you give it a directory, grml2usb assumes you set up a bootloader on your own (or don't need one), and a bootloader won't be installed automatically.

the following options are supported:

  • --bootoptions=... — use the specified bootoptions as default. and bestie, if you wanna use the flavour name as an argument for a boot parameter, use %flavour — it expands to the flavour name. want multiple bootoptions? just specify this option multiple times. 💖
  • --bootloader-only — don't copy files, just install a bootloader. note that the boot addons still get copied to /boot/addons at this stage. if you'd rather skip copying the boot addons too, consider the --skip-addons option.
  • --copy-only — copy files only but do not install a bootloader.
  • --dry-run — avoid executing commands, instead show what would be executed. warning bestie: the ISO has to be mounted anyway, otherwise identifying the Grml flavour wouldn't be possible. 🙈
  • --format — format the specified partition with FAT. important: this will destroy any existing data on the specified partition!! like, gone-gone. 😭
  • --force — force any (possible dangerous) actions requiring manual interaction (like --format).
  • --grub — install grub bootloader instead of (default) syslinux.
  • --grub-mbr — install grub into MBR (Master Boot Record) instead of PBR (Partition Boot Record). check out the mbr-vs-pbr section in the FAQ of this document for further details.
  • --help — display usage information and exit. 🫶
  • --mbr-menu — install master boot record (MBR) with integrated boot menu: interactively choose the partition to boot from, with a timeout to load the default partition, or boot from floppy. when you're NOT using the --mbr-menu option, an MBR with LBA and large disc support but without an integrated boot menu gets installed (so it's not visible at all but instead directly jumps to the bootloader — being grub or syslinux). note: this option is available only when using the default MBR and won't have any effect if you're using the --syslinux-mbr option.
  • --quiet — do not output anything but just errors on console. silence is golden, as they say. 🤫
  • --skip-addons — do not install /boot/addons/ files (like dos, grub, memdisk,...).
  • --remove-bootoption=... — remove the specified bootoption (could be a regex) from existing boot options. use multiple entries to remove different bootoptions all at once.
  • --skip-bootflag — do not check for presence of boot flag on target device.
  • --skip-grub-config — skip generation of grub configuration files. by default the configuration files for syslinux and grub will be written, so you've got a working configuration file no matter whether you're using grub or syslinux as bootloader. 💫
  • --skip-mbr — do not touch/install the master boot record (MBR).
  • --skip-syslinux-config — skip generation of syslinux configuration files. by default the configuration files for syslinux and grub will be written, so you've got a working configuration file no matter whether you're using grub or syslinux as bootloader. ✨
  • --skip-usb-check — skip the check that verifies whether the given device is a removable device. some USB devices are known to report wrong information — when you're using such a device you can skip grml2usb's removable device check. 🍓
  • --syslinux — this option is deprecated and is being left only for backwards compatibility reasons. syslinux is the default bootloader of grml2usb and therefore the --syslinux option doesn't have any effects. if you do not want to use syslinux as bootloader, consider using the --grub option.
  • --syslinux-mbr — install syslinux' master boot record (MBR, which is booting from the partition with the "active" flag set) instead of the default one. if you encounter any problems with the default MBR you can try using the syslinux MBR instead. and if that works for you, please let us know so we can adjust our default MBR accordingly. 🫶
  • -v, --version — return version and exit.
  • --verbose — enable verbose mode. give me ALL the output bestie. 🔥

🛠️ DEVELOPERS CORNER 🛠️

🌈 Directory layout on USB device 🌈

boot/ ->
  |-- addons/
  |   |-- ...              [as provided on ISO]
  |-- release/
  |   |-- grml/
  |   |   |-- vmlinuz      [Kernel]
  |   |   |-- initrd.gz    [initramfs]
  |   |-- grml64
  |   |   |-- vmlinuz      [Kernel]
  |   |   |-- initrd.gz    [initramfs]
  |   |-- grml-small
  |   |   |-- vmlinuz
  |   |   |-- initrd.gz
  |   `-- grml64-small
  |       |-- vmlinuz
  |       |-- initrd.gz
  |-- grub/
  |   |-- grml.png         [graphical bootsplash background image for grub2]
  |   |-- grub.cfg         [configuration file for grub2]
  `-- syslinux/
      |-- grml.png         [graphical bootsplash background image for syslinux]
      |-- syslinux.cfg     [main configuration file for syslinux]
      `-- [....]           [several further config files for syslinux]

grml/
  |-- grml2usb.txt         [not yet implemented]
  |-- grml-cheatcodes.txt  [list of bootoptions for Grml]
  |-- grml-version.txt     [file containing information about grml-version]
  |-- LICENSE.txt          [license information]
  |-- md5sums              [md5sums of original ISO]
  |-- README.txt           [informational text]
  `-- web/                 [browser related files]
      |-- index.html
      |-- style.css
      `-- images/
          |-- button.png
          |-- favicon.png
          |-- linux.jpg
          `-- logo.png

live/
  |-- grml/
  |   |-- filesystem.module    [module specifying which squashfs should be used for grml]
  |   `-- grml.squashfs        [squashfs file for grml]
  |-- grml-small/
  |   |-- filesystem.module    [module specifying which squashfs should be used for grml-small]
  |   `-- grml-small.squashfs  [squashfs file for grml-small]
  `-- ...

🎀 Grabbing the source 🎀

% git clone https://github.com/grml/grml2usb.git

🐛 Developers Debugging Hints 🐛

to play with grml2usb you can avoid using a real device via a loopback file setup, like:

# dd if=/dev/zero of=~/loopback bs=1M count=100 # adjust size to your needs
# losetup /dev/loop1 ~/loopback

then create according partitions either running for example:

# echo -en "n\np\n1\n\n\nt\n6\na\n1\n w\n" | fdisk /dev/loop1

or:

# parted /dev/loop1 -s "mkpart primary fat32 0 -1s mkfs 1 fat32"

finally create a filesystem and execute grml2usb as needed:

# mkfs.vfat /dev/loop1
# grml2usb --bootloader-only /grml/isos/grml-full-2025.08-amd64.iso /dev/loop1

🔍 Performance tracing 🔍

# blktrace -d /dev/sdX -o - | blkparse -i -
# grml2usb grml-full-2025.08-amd64.iso /dev/sdX1

🔧 TROUBLESHOOTING AND PITFALLS WHEN BOOTING 🔧

okay bestie, vibe check time 💅 here's the whole lineup of error messages your BIOS/bootloader might hit you with when you're trying to boot from USB. Find yours, fix yours, move on with your life ✨

ran out of input data. + System halted

shows up like this:

ran out of input data.
System halted

the tea ☕: literally everything is fine, except the filesystem on your USB device. So instead of fat16 you went and used, say, fat32. the fix: use the appropriate filesystem (for a USB flash drive that's usually fat16). Sneaky detail: the bootsplash might actually display, the kernel loads... and then you get the error message really soon after. Rude, honestly 😭

Invalid operating system

the tea ☕: your partition layout is not it. Lowkey most likely there's no primary partition (/dev/sdX{1..4}) at all, or none of them has the bootable flag set. 🫠

Boot error.

the tea ☕: some BIOSes offer different modes for USB booting, and the proper mode for booting a USB stick is USB-HDD. If that doesn't work, or your system doesn't support it, you need to format your USB-Stick as USB-ZIP. To do that, syslinux ships a utility called mkdiskimage, which you can use to re-format your USB stick in USB-ZIP format by running:

mkdiskimage -4 /dev/sdX 1 64 32
⚠️ please be aware that this procedure will erase all data on your stick. rip 🙈

After running mkdiskimage just continue installing as usual:

grml2usb ... /dev/sdX4

Note that this is not going to work for any device larger than 8 GB, since mkdiskimage only supports 1024c 256h 63s. For a more detailed explanation, refer to /usr/share/doc/syslinux-common/usbkey.txt. 📖

No operating system found.

the tea ☕: you forgot to set the boot-flag on the partition. Or there really isn't any operating system at all. :) 😌

kernel-panic: unable to mount root-fs...

the tea ☕: the kernel boots but fails to find the root filesystem. Your root= argument in the kernel commandline is pointing at the wrong device. Adjust root=..., and consider using root=UUID=.... 💡

Could not find kernel image: ...

the tea ☕: either a broken isolinux/syslinux version or a broken BIOS. Check out whether the vendor provides a BIOS update, or whether using bootloader grub instead of isolinux/syslinux fixes the problem. 🧚

🌸 FREQUENTLY ASKED QUESTIONS (FAQ) 🌸

Where can I get grml2usb?

grml2usb is available as a Debian package via the grml-testing Debian repository[1] ✨

If you do not want to (or can't) use the grml2usb Debian package, you can either use the grml2usb git tree by running:

git clone https://github.com/grml/grml2usb.git
cd grml2usb
sudo ./grml2usb ...
📌 Note: it is NOT enough to have just the grml2usb script itself without the according files provided either via the Debian package or the git tree. it's giving "script without its friends" energy 💀

Why can't I just dd the ISO to a USB device?

Well... you can. :) Starting with Grml 2009.10 the ISOs are dd-able straight out-of-the-box. 🎉

⚠️ Important: note that ANY existing data on your USB device will be destroyed when using the dd approach. gone. obliterated. no take-backs 🫶

This allows you to dd the Grml ISO to your USB device (use for example rawwrite[2] if you've just a Windows system available) by running:

% dd if=grml-full-2025.08-amd64.iso of=/dev/sdX

where /dev/sdX is your USB device. Of course this doesn't provide such a flexible system like with grml2usb (no multi-ISO setup, no additional default bootoptions, ...) but it's a nice way to get a working USB boot setup if you don't have grml2usb available. 💁‍♀️

What's the difference between grml2usb and just using dd?

grml2usb does not remove any data from your USB device and does not alter the partition table at all. grml2usb provides multi-ISO support, support for adding default bootoptions and selecting the bootloader (syslinux vs. grub) without having to manually touch the ISO at all. main character behavior, honestly 👑

What's grml2iso?

grml2iso is a script which uses grml2usb to generate a multiboot ISO out of several Grml ISOs. See man grml2iso for further details. 🔥

grub-install complains about /sbin/grub-install and/or xfs_freeze?!

The following message:

You shouldn't call /sbin/grub-install. Please call /usr/sbin/grub-install instead!
xfs_freeze: specified file ["/tmp/tmpqaBK6z/boot/grub"] is not on an XFS filesystem

This is "normal". grub-install sends those messages to stderr. To avoid hiding any possible real error messages, grml2usb doesn't ignore those messages. 😤

grub-install complains about a unary operator?!

The following message:

'/usr/sbin/grub-install: line 374: [: =: unary operator expected'

This is "normal". Just ignore it. (It usually doesn't appear on the second invocation on the same device.) 🙃

grub-install fails with grub-probe: error: unknown filesystem?!

The following message:

grub-probe: error: unknown filesystem
Auto-detection of a filesystem module failed.
Please specify the module with the option `--modules' explicitly.

usually means that the device partition table says something else than the filesystem on the device. For example, using FAT16 as filesystem type and using FAT32 as filesystem on the partition will not work. Either set the filesystem type to FAT32 or format the partition using FAT16. It is essential that device partition table and filesystem use the same filesystem type — they gotta match, bestie, it's a whole relationship 💞

grub-setup fails after "Attempting to install GRUB to a partition instead of the MBR"?!

The following message:

grub-setup: warn: Attempting to install GRUB to a partition instead of the MBR.  This is a BAD idea.
grub-setup: warn: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and its use is discouraged.
grub-setup: error: Cannot read `/grub/core.img' correctly

appears when using grub2 versions older than 1.98, as those versions introduced a regression which avoids that grub is being installed into a partition (PBR, Partition Boot Record) instead of MBR (Master Boot Record). 🫠

To work around this issue you can either:

  1. upgrade to grub versions >=1.98,
  2. install grub into the MBR (Master Boot Record) using the --grub-mbr option of grml2usb, or
  3. switch to syslinux as bootmanager (just drop the --grub option).

I'm getting something like Error: /usr/share/grml2usb/grub/splash.xpm.gz can not be read"!?

Looks like you've only got the grml2usb script itself available. Please make sure you've the grml2usb Debian package installed. The most recent stable version is available via the grml-testing Debian repository[1]. If you do not have a Debian system, please see section Where can I get grml2usb? in this FAQ. 🎀

Why do I have to use a FAT16/FAT32 filesystem?

Syslinux (currently) does not support any other filesystems besides FAT16/FAT32 (though that's a sane default if you want to share your files with other (operating) systems). If you want to use a different filesystem (like ext2/3) use the bootloader grub instead, using grml2usb's --grub option. 🌈

I think I've got a really cool idea!

Great! Please check out the TODO file[3]. Feel free to report your wishes to the author. Patches highly appreciated. 🫶

I've problems with booting from USB.

Check out Troubleshooting and Pitfalls when booting. ⬆️

I've found a bug!

Please report it to the author. Please provide usage examples and output of your grml2usb commandline (consider using the "--verbose" option). 🐛

💖 USAGE EXAMPLES 💖

# grml2usb /home/grml/grml-full-2025.08-amd64.iso /dev/sdX1

Install specified ISO on device /dev/sdX1. ✨

# grml2usb /home/grml/grml-full-2025.08-amd64.iso /home/grml/grml-full-2025.08-arm64.iso  /dev/sdX1

Install specified ISOs on device /dev/sdX1 for multibooting ISOs. 🔥

# grml2usb /run/live/medium /dev/sdX1

Install currently running Grml live system on device /dev/sdX1. 🌸

# grml2usb /run/live/medium /home/grml/grml-full-2025.08-amd64.iso /dev/sdX1

Install currently running Grml live system and the specified ISO on device /dev/sdX1 for multibooting. 💫

# grml2usb --format /home/grml/grml-full-2025.08-amd64.iso /dev/sdX1

Install specified ISO on device /dev/sdX1 and format partition /dev/sdX1 with FAT filesystem. 🧼

# grml2usb --grub --grub-mbr /home/grml/grml-full-2025.08-amd64.iso /dev/sdX1

Install specified ISO on device /dev/sdX1 and use grub as bootloader (instead of syslinux being the default) and install a master boot record (MBR) to the MBR of /dev/sdX. 👑

# grml2usb --bootoptions="lang=de ssh=mysecret" grml-full-2025.08-amd64.iso /dev/sdX1
# grml2usb --bootoptions="lang=de" --bootoptions="ssh=mysecret" grml-full-2025.08-amd64.iso /dev/sdX1

Install specified ISO on device /dev/sdX1 and use "lang=de ssh=mysecret" as default bootoptions. 💬

# grml2usb --remove-bootoption="vga=791" --remove-bootoption="nomce" grml-full-2025.08-amd64.iso /dev/sdX1

Install specified ISO on device /dev/sdX1 remove vga=791 and nomce from existing bootoptions. ✂️

# grml2usb --bootoptions="persistent-path=%flavour_name" grml-full-2025.08-amd64.iso grml-full-2025.08-arm64.iso /dev/sdX1

Install specified ISOs on device /dev/sdx and add parameter persistent-path to every menu entry. %flavour_name will be expanded to the flavour of the specific iso, e.g. grml64 and grml. 🦋

🌟 ONLINE RESOURCES 🌟

Check out the grml2usb webpage[4], the grml2usb git repository[5] and the wiki for persistency[6]. go click, bestie 💅

🐛 BUGS 🐛

Please report feedback, bugreports and wishes to the author.

👑 AUTHOR 👑

Michael Prokop <mika@grml.org>[7]

✨ NOTES ✨

okay bestie, here's the receipts folder 💅 every single one of these is linked from the manpage, so if you wanna go deeper, this is your lil treasure map 🗺️💖

  1. the grml-testing Debian repository — https://deb.grml.org/
  2. rawwrite — http://www.chrysocome.net/rawwrite
  3. the TODO file — https://github.com/grml/grml2usb/blob/master/TODO
  4. grml2usb webpage — https://grml.org/grml2usb/
  5. grml2usb git repository — https://github.com/grml/grml2usb
  6. persistency — https://github.com/grml/grml/wiki/persistency
  7. mika@grml.org — mailto:mika@grml.org

and that's the whole page, bestie 🎀 you made it to the end, slay fr fr 👑

oh and before you go — this whole thing is the GRML2USB(8) manual, and it's dated 05/20/2026 at the bottom, just so you know exactly which version of the vibe you're reading 🌸 she's current, she's iconic, she's literally the manual 💅✨

📦 where this page comes from