Script command to manipulate binary file (on linux)

Question

I am looking for a mechanism to manipulate my eeprom image with a unique device id. I'd like to do this in a make file so that the device would automatically obtain a new ID and then update it to the data image, then flash it. In pseudocode:

wget http://my.centralized.uid.service/new >new.id
binedit binary.image -write 0xE6 new.id
flash binary.image into device

So first we get an id into a separate file, then we overwrite the image (from given offset) with the contents of this ID file. Then flash. But how to do the second part? I looked up bvi, which seems to have some scripting abilities, but I did not fully understand it, and to be honest vi always gave me the creeps.

Thanks for help beforehand!

possible duplicate of Bash Scripting: How to patch files? (write a given string in a given position of a file) — chepner
– chepner, Commented Sep 4, 2012 at 13:18

chepner · Accepted Answer · 2012-09-04 13:23:46Z

2

(Full disclosure: I made the initial vote to close as a duplicate. This answer is adapted from the referenced question.)

Use dd with the notrunc option:

offset=$(( 0xe6 ))
length=$( wc -c < new.id )
dd bs=1 if=new.id of=binary.image count=$length seek=$offset conv=notrunc

You may want to try this on a copy first, just to make sure it works properly.

answered Sep 4, 2012 at 13:23

chepner

538k77 gold badges594 silver badges746 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hannes R. Over a year ago

You are right, is a duplicate. I did not include "patching" in original keyword searches. And the answer is exactly what I was after. Thanks!

Lee Netherton · Accepted Answer · 2012-09-04 11:41:39Z

2

If you know the offset of the file that you want to replace from, you can use the split command to split the initial file up until the offset. The cat command can then be used to join the required pieces together.

Another useful tool when working with binary files is od which will let you examine the binary files in human readable format.

answered Sep 4, 2012 at 11:41

Lee Netherton

22.8k12 gold badges74 silver badges103 bronze badges

1 Comment

Hannes R. Over a year ago

mm, the split/cat solution is quite innovative, never thought of that.

Brian Agnew · Accepted Answer · 2012-09-04 11:35:28Z

0

I would perhaps use something like Perl. See here and in particular the section labelled Updating a Random-Access File (example here)

answered Sep 4, 2012 at 11:35

Brian Agnew

273k38 gold badges342 silver badges443 bronze badges

Collectives™ on Stack Overflow

Script command to manipulate binary file (on linux)

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related