Any command-line tools for copying PNG chunks from A to B?

[Bloax]

Bad topic name, probably. And it's also kind of weird posting a topic here after being a lurker for what's probably over three-four years now. But yeah, pretty simple question:

• Are there any batch-processing-friendly programs to copy some arbitary data chunks from one PNG file to another?

• I'm asking because it doesn't seem to be of much interest (and it really is a stupendous minority), and because searching doesn't yield anything.

• TweakPNG does it quite fine, but I would much prefer to just automate this.

Thanks in advance, I guess? (/awkwardface) (And I have no idea why my linebreaks get converted to spaces, so enjoy the list tags which at least break it up.)

[caveman]

It's relatively easy to write since each chunk is an independent binary entity there are only a few ordering rules to follow, what kind of chunks would you like to move over? What behavior do you expect if the chunk already exists in the second file?

[Bloax]

Pretty much an arbitrary "garbage" chunk which is important in this one engine I primarily do stuff for. Namely the "grAb" chunk, which is present in one, and not present in the other.. As for behavior, the optimal solution would be if one had to define it through a flag (eg. -f would force overwrite, otherwise it would bitch with an error at you), but overwriting without asking would do fine too.