kpartx:tldr:4e292

The "kpartx" command is used in Linux to create device mappings for partitions on a disk image.

The "-a" flag is used to add partitions from the specified disk image.

"${whole_disk-img}" is a placeholder for the path or name of the whole disk image file. This could be something like "/dev/sdb" for a physical disk or a path to a disk image file like "/path/to/disk.img".

So, when you run the command "kpartx -a ${whole_disk-img}", it will scan the specified disk image file and create device mappings for the partitions found within the image. These mappings will typically be in the form of device files such as "/dev/mapper/loop0p1", "/dev/mapper/loop0p2", and so on, representing each of the partitions on the disk image. These device files can then be used to interact with the individual partitions within the disk image as if they were separate block devices.