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Exploring .img Files on Linux and create your custom one

keopx — Thu, 26 Dec 2019 10:50:37 +0000

Exploring .img Files on Linux and create your custom one

Discover the hidden secrets of a monolithic .img file
Mount the partitions in an .img file using losetup, kpartx and mount
Create your own .img files and use them as virtual disks
Write out your virtual disk image to a thumb drive (or any drive for that matter) for use later

Install packages

$ sudo aptitude install kpartx xz-utils

Decompress image

Once its downloaded you will want to uncompress it with xz --decompress:

$ xz --decompress Retrobro128KillerHomeConsole.img.img.xz

Mount image

We’re going to attach the image file to what is known as a loopback device.

$ sudo losetup /dev/loop0 Retrobro128KillerHomeConsole.img

Note: We used /dev/loop0 in this example. If /dev/loop0 wasn’t available to us (that is, it was already in use), we could have chosen /dev/loop1, etc.

$ sudo losetup -a /dev/loop0: [65026]:28970069 (/home/keopx/Retrobro128KillerHomeConsole.img)

Now /dev/loop0 is attached. How about look at the partition table with fdisk?

$ sudo fdisk -l /dev/loop0 Disco /dev/loop0: 119,8 GiB, 128579534848 bytes, 251131904 sectores Unidades: sectores de 1 * 512 = 512 bytes Tamaño de sector (lógico/físico): 512 bytes / 512 bytes Tamaño de E/S (mínimo/óptimo): 512 bytes / 512 bytes Tipo de etiqueta de disco: dos Identificador del disco: 0xf2d3cb4f Disposit. Inicio Comienzo Final Sectores Tamaño Id Tipo /dev/loop0p1 * 8192 124927 116736 57M e W95 FAT16 (LBA) /dev/loop0p2 124928 251131903 251006976 119,7G 83 Linux

To see what kpartx would map, run it with the -l option:

$ sudo kpartx -l /dev/loop0 loop0p1 : 0 116736 /dev/loop0 8192 loop0p2 : 0 251006976 /dev/loop0 124928

Let’s go ahead and run it and add the maps:

$ sudo kpartx -a /dev/loop0

Now you can see new devices on dolphin.

Running a shell:

Now that the partitions are mapped, let’s examine the filesystems on each partition with file and the --special-files and --dereference options.

$ sudo file -sL /dev/mapper/loop0p1 /dev/mapper/loop0p1: DOS/MBR boot sector, code offset 0x3c+2, OEM-ID "mkfs.fat", sectors/cluster 4, reserved sectors 4, root entries 512, Media descriptor 0xf8, sectors/FAT 116, sectors/track 32, heads 64, sectors 116736 (volumes > 32 MB), serial number 0xb13de1e5, label: "boot ", FAT (16 bit)

$ sudo file -sL /dev/mapper/loop0p2 /dev/mapper/loop0p2: Linux rev 1.0 ext4 filesystem data, UUID=c50e928e-5669-44d0-8e3c-a59d21ad3da2, volume name "retropie" (extents) (64bit) (large files)

Now that we have our partitions mapped, we can mount them. Create two directories to serve as mountpoints:

$ mkdir boot # We will mount the FAT partition here $ mkdir retropie # We will mount the ext4 partition here

Once they are created, mount the filesystems (only system in my case).

$ sudo mount /dev/mapper/loop0p2 retropie

Umount image

Once you are done and want to “let go” of the .img file, reverse the process with:

$ sudo umount retropie $ sudo kpartx -d /dev/loop0 $ sudo losetup -d /dev/loop0

Reference:

https://dev.iachieved.it/iachievedit/exploring-img-files-on-linux/

keopx Jue, 26/12/2019 - 11:50

Categoria

Debian 10

Raspberry pi

Tag

bash

Terminal

consola

Comentarios

Simplifica los accesos remotos con ~/.ssh/config

keopx — Sat, 23 Jun 2012 07:59:19 +0000

Simplifica los accesos remotos con ~/.ssh/config

Para poder acceder a equipos remotos de forma ágil y sencilla podemos utilizar el fichero ~/.ssh/config que nos permite definir equipos, puertos, usuarios, rsa,... que nos facilitara la vida.

Queremos una clave diferente para acceder a github.com su propia clave.

Editamos:

nano ~/.ssh/config

Podemos seguir el siguiente ejemplo:

Host github.com
  User git
  Hostname github.com
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/git_rsa

O acceder por ssh a un server donde hemos configurado el puerto de ssh en el 7020:

Host server1
  User keopx
  Port 7020
  Hostname 82.140.251.152

Por ejemplo para acceder a server1 únicamente seria necesario:

ssh server1

Leería esta configuración y accederíamos directamente al equipo en vez de tener que escribir lo siguiente:

ssh -p 7020 keopx@82.140.251.152

keopx Sáb, 23/06/2012 - 09:59

Categoria

Terminal

Exploring .img Files on Linux and create your custom one

Install packages

Decompress image

Mount image

Umount image

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