I wanted to install the sBitx software to another SD card to have a backup. I downloaded it from (as described in ). However, an attempt to do on my laptop (in your case instead of mmcblk0 you may need to use sdX where X is another character):
dd if=sBitx_3.21.img of=/dev/mmcblkp0 bs=4M
resulted in interrupted writing due to lack of space on the SD card.
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So I had to reorganize the image.
Please remember that the procedure describe below involves running potentially dangerous commands as root. Be sure, that you don't run them with incorrect device name. Otherwise, you may destroy the filesystem on your workstation or laptop. You do it on your own risk. I hope that I have not mistaken in the description below, but I don't give you any warranty. You must understand what are you doing.
- As root I have mounted the image:
losetup -P -f? ./sBitx_3.21.img
- I have checked which loop devices where assigned to it:
losetup -a
In my case it was:
/dev/loop0: [64770]:61762171 (/home/wzab/sBitx/sBitx_3.21.img)
- I have verified that the partitions were detected:
ls /dev/loop0*
/dev/loop0 ?/dev/loop0p1 ?/dev/loop0p2
- I have resized the the filesystem on the second partition of the image (in your case another loop device may be used, see results of the previous step):
resize2fs /dev/loop0p2 20G
resize2fs 1.47.2 (1-Jan-2025)
Please run 'e2fsck -f /dev/loop0p2' first.
The first attempt failed, so I ran the suggested command:
e2fsck -f /dev/loop0p2
[...]
rootfs: 269323/1933312 files (0.1% non-contiguous), 2387299/7725184 blocks
An additional advantage was that I learned how big the filesystem is: 2387299 4KiB blocks (9778376704 bytes). After its successful completion I ran resize2fs again:
?resize2fs /dev/loop0p2 20G
resize2fs 1.47.2 (1-Jan-2025)
Resizing the filesystem on /dev/loop0p2 to 5242880 (4k) blocks.
- I checked the size of all partitions in my image:
?fdisk -l /dev/loop0
Disk /dev/loop0: 29.72 GiB, 31914983424 bytes, 62333952 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: 0xf8f9cbd4
Device ? ? ? Boot ?Start ? ? ?End ?Sectors ?Size Id Type
/dev/loop0p1 ? ? ? ?8192 ? 532479 ? 524288 ?256M ?c W95 FAT32 (LBA)
/dev/loop0p2 ? ? ?532480 62333951 61801472 29.5G 83 Linux
- So I need to add 256 MB for VFAT partition. To be safe, I resize the image to 21 GB:
losetup -d loop0
truncate sBitx_3.21.img --size 21G
fdisk sBitx_3.21.img
In the fdisk I used p command to print the partitions:
fdisk ./sBitx_3.21.img?
Welcome to fdisk (util-linux 2.40.4).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk ./sBitx_3.21.img: 21 GiB, 22548578304 bytes, 44040192 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: 0xf8f9cbd4
Device ? ? ? ? ? ?Boot ?Start ? ? ?End ?Sectors ?Size Id Type
./sBitx_3.21.img1 ? ? ? ?8192 ? 532479 ? 524288 ?256M ?c W95 FAT32 (LBA)
./sBitx_3.21.img2 ? ? ?532480 62333951 61801472 29.5G 83 Linux
It is clear that the second partition spans outside the image (sector 61801472, while 44040192 sectors are available)
- I correct the partition table. I write somewhere the start sector of partition 2. Then I delete the 2nd partition by pressing "d" and "2"
Command (m for help): d
Partition number (1,2, default 2): 2
Partition 2 has been deleted.
Then I recreate the second partition, by pressing "n", "p" and "2":
Command (m for help): n
Partition type
? ?p ? primary (1 primary, 0 extended, 3 free)
? ?e ? extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2): 2
First sector (2048-44040191, default 2048): 532480
Last sector, +/-sectors or +/-size{K,M,G,T,P} (532480-44040191, default 44040191):?
Created a new partition 2 of type 'Linux' and of size 20.7 GiB.
Partition #2 contains a ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: n
Please note, that I had to enter the stored start sector number (fdisk proposed 2048, which was wrong).
The proposed end factor is the last available sector, which is OK.
- Finally I can write the corrected partition with command "w".
- The reworked sBitx_3.21.img may now be written to a slightly smaller SD card.
- To fully utilize the SD card capacity, you may repeat the step 7 on your SD card.
Assuming this is /dev/mmcblk0, you should run fdisk /dev/mmcblk0 and set the end sector of partition 2 to the last sector in the card.
Please remember that the filesystems from /dev/mmcblk0p1 and /dev/mmcblk0p2 should not be (auto)mounted! If they are mounted, unmount them first!
- Finally you may resize the filesystem (if you do not give the size, the filesystem will be extended to the whole capacity of the partition)
resize2fs /dev/mmcblk0p2
?
If performed carefully, the above procedure allows you to write the sBitx SD card image to a smaller card.
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73,
Wojtek
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Shirley Dulcey KE1L
HA3HZ
Peter VK3PYE