How to get hex offset of string
 

Hi.

I got a file, that I want to patch. I know the hex code I want to patch, but not the offset. How can I do that? Now I am looking for terminal software, that allows me to get the offset of the string, so I can pipe it to xxd.

Thanks.

Not sure why you need xxd, you can just do an inplace edit with sed

Because sed cannot replace by offset, just by hex code. Or can it?

sed and xxd are not my problem. The problem is to get the offset.

Usually to patch binaries you can just match a longer set of hex chars to make it more unique, try 'grep -c <pattern>' with longer patterns until you only get one match then feed it into sed for the search and replace.

Sorry, in answer to your actual question try diff and patch, I can't say I've tried but they're probably a good bet.

Thanks for the ideas. One problem is that I also have to patch single bytes, which can only be done by offset or I would patch any matching byte of the whole file.

I know of bgrep:
https://github.com/tmbinc/bgrep

In the past I have made patches in C that search for and patch intelligently.

I also found the program called strings.

Thanks. Linux mates are the best.