Shrink an .img file from the command line
I need to be able to shrink the .img for use on other drives. I can do this using gparted, but do not always have a GUI, so I want to translate the gparted step below into parted
to be verbose, here is my whole proceedure using gparted
insert sd card
$ lsblk
copy image
$ sudo dd bs=4M if=/dev/mmcblk0 of=rp4-ubuntu-server-22.04-fresh.img status=progress oflag=sync
create a loopback device
$ sudo losetup -f
$ sudo losetup /dev/loop0 /home/phil/dl/rp4-ubuntu-server-22.04-fresh.img
$ sudo partprobe /dev/loop0
resize the partition (This is where I need help!)
$ sudo gparted /dev/loop0
resize --> drag to desired size --> apply --> exit gparted
done with the loopback device
$ sudo losetup -d /dev/loop0
find last sector
$ fdisk -l /home/phil/dl/rp4-ubuntu-server-22.04-fresh.img
Disk /home/phil/dl/rp4-ubuntu-server-22.04-fresh.img: 59.63 GiB, 64021856256 bytes,
125042688 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x1b140081
Device Boot Start End Sectors Size Id Type
/home/phil/dl/rp4-ubuntu-server-22.04-fresh.img1 * 2048 526335 524288 256M
c W95 FAT32
/home/phil/dl/rp4-ubuntu-server-22.04-fresh.img2 526336 7739391 7213056 3.4G 83 Linux
resize the .img
$ sudo truncate --size=$[(7739391+1)*512] /home/phil/dl/rp4-ubuntu-server-22.04-fresh.img
