ImgUtil is a Win32 utility for modifying Android boot images. (It was formerly named "bootutil.exe".)

Often you need to modify a boot image in small ways, e.g. modifying default.prop inside a ramdisk. There are the standard ways to completely take apart a boot image. After modifications, you can pack the image back together again. This is all a bit needless. There is also the problem of trying to save Linux ownership, mode and symlinks on a Windows system. It's easier to just extract what you need, modify it, then replace the original file.

Usage: imgutil [flags] image [file...] /l list files /r replace files /i insert files /a append files /s symlink (target) /d delete files /x extract files /t use file timestamps /m file mode /g group id /u user id /c set command line /v verbose

An example:

C:\>imgutil boot.img /x /v default.prop C:\>your-text-editor default.prop C:\>imgutil boot.img /r /v default.prop

ImgUtil can handle bare ramdisks, Linux style images with ramdisks and Android style images with ramdisks. It can also handle images with DTB segments in them.

Beta Features

There are two filenames that are handled specially, "kernel" and "payload". You can use the /x and /r flags to extract or replace the kernel.

C:\>imgutil bootimg /x /v kernel

Some kernels are not overall compressed but they have a decompressing stub and a compressed payload. You can (possibly) extract the uncompressed payload. Replacing the payload involves adjusting offsets. As of now, it is only (somewhat) proven to work on Nook images.

C:\>imgutil bootimg /x /v payload

Download the executable.