The reason for needing this could be e.g. reinstalling Windows but it could also be to update your system firmware - because the vendor only provided Windows binaries - you need a Windows system.
To update you system firmware you can use a Windows PE environment like Hiren's BootCD Hirens BootCD
If you want to reinstall Windows after your Manjaro adventure get a Windows ISO from Microsoft
Only the manual approach described below was viable - until af few years ago when the github user slacka forked the WinUSB project. Thanks to his work the Linux community have an app to do abstract the CLI work.
Very receently a new tool has become available - the ventoy project - which makes the task even easier.
[date=2020-05-09 time=12:35:00 timezone="Europe/Copenhagen"] The ventoy utility is a great tool for booting a Windows ISO without having to jump through the hoops in this guide.
Install the ventoy package from repo
sudo pacman -S ventoy
Locate your USB stick
Replace sdy below with your device
sudo ventoy -i /dev/sdy
Using your file manager and drag your Windows ISO onto you USB and wait - patience is the keyword - patience.
exclamation: If you don't wait - data corruption will occur - and you don't want that.
Using the device name from above mount the first partition to a temporary mount point
sudo mount /dev/sdy1 /mnt
Copy the ISO file to the USB - assuming the ISO is in your Downloads folder
cp ~/Downloads/<windows.iso> /mnt && sync
When the command finishes you can unmount the device
sudo umount /mnt
:exclamation: If you don't wait - data corruption will occur - and you don't want that.
Use the package woeusb available from [AUR]
pamac build woeusb
Tip from @codesardine in a [comment]
Before launching the app
sudo modprobe -nv loop
Then launch the app and get your ISO done.
Remove all removable devices (USB), open a terminal and list known disk devices
Insert your USB stick and list your devices one more time
Make a note of the extra device listed. If you only have one disk then it probably will be
Please do double check the device id
In the terminal clear the disk of any partition info, using this command (replace sdy with device letter from above).
sudo dd if=/dev/zero of=/dev/sdy bs=1M count=10 oflag=sync
Then use fdisk to create the filesystem needed for the Windows ISO (replace X with device letter from above).
sudo fdisk /dev/sdy
The commands in fdisk is as follows
[date=2019-11-01 time=17:43:00 timezone="Europe/Copenhagen"] The partitioning may need rework due to single file inside Windows ISO is larger than 4G.
Newer versions of Windows 10 ISO contains a file bigger than 4G. Format the device using exfat or ntfs (replace sdy with device letter from above) to overcome the size limitation of FAT32.
sudo mkfs.ntfs /dev/sdX1
Create a folder to mount your ISO
Mount your ISO
sudo mount -o loop /path/to/windows/iso/filename.iso ~/winiso
Create a folder to mount your USB
Mount the partition (replace sdy with device letter from above)
sudo mount /dev/sdy1 ~/winusb
Copy all files from ISO to USB
cd ~/winiso cp -r * ~/winusb
The copy operation is going to take a long time depending on your USB port speed and your USB device.
When the copy is done ensure all data is flushed to the device using the sync command
When all data is flushed to the device you will be returned to the prompt. Next thing is to move out of the winiso folder
Then unmount the devices
sudo umount ~/winiso ~/winusb
Remove the folders
rm -rf ~/winiso ~/winusb
You should now be able to boot to your Windows install media.