(This question should be migrated to unix as it's not raspberrypi specific)

1. Zero free space on the running system (there are a few ways but zerofree is a simple one)
2. Make the .img
3. Compress with 7z (zip and rar also work but 7z as they can use 7z's open LZMA2 compression).
4. Using backup software will store only the differences in each backup (more effectively without step #3)

You can further reduce .img size by clearing logs, caches, unused packages etc.

As a system backup solution it is often best to keep an install.log you can run (or follow) on a fresh install as you will want to upgrade, or use a different distribution and guessing what you did and why from a backup image is not worth the effort.

If you are backing up data and not the OS then backup software has numerous advantages.

1. Zero free space on the running system (there are a few ways but zerofree is a simple one)
2. Make the .img
3. Compress with 7z (zip and rar also work but 7z as they can use 7z's open LZMA2 compression).
4. Using backup software will store only the differences in each backup (more effectively without step #3)

You can further reduce .img size by clearing logs, caches, unused packages etc.

As a system backup solution it is often best to keep an install.log you can run (or follow) on a fresh install as you will want to upgrade, or use a different distribution and guessing what you did and why from a backup image is not worth the effort.

If you are backing up data and not the OS then backup software has numerous advantages.

1. Zero free space on the running rpi (there are a few ways but zerofree is a simple one)
2. Make the .img
3. Compress with 7z (zip and rar also work but 7z as they can use 7z's open LZMA2 compression).
4. Using backup software will store only the differences in each backup (more effectively without step #3)

You can further reduce .img size by clearing logs, caches, unused packages etc.

As a system backup solution it is often best to keep an install.log you can run (or follow) on a fresh install as you will want to upgrade, or use a different distribution and guessing what you did and why from a backup image is not worth the effort.

If you are backing up data and not the OS then backup software has numerous advantages.

(This question should be migrated to unix as it's not raspberrypi specific)

1. Zero free space on the running system (there are a few ways but zerofree is a simple one)
2. Make the .img
3. Compress with 7z (zip and rar also work but 7z as they can use 7z's open LZMA2 compression).
4. Using backup software will store only the differences in each backup (more effectively without step #3)

You can further reduce .img size by clearing logs, caches, unused packages etc.

As a system backup solution it is often best to keep an install.log you can run (or follow) on a fresh install as you will want to upgrade, or use a different distribution and guessing what you did and why from a backup image is not worth the effort.

If you are backing up data and not the OS then backup software has numerous advantages.