I want to add a minimal amount of data at the end of a compressed file.

It would be cool if by running a command from bash, such data would be inserted at the end of the existing file.

This would also be used with large files like 50MB for example, and added data can be around 1 Byte.

In Windows the script is doing an echo of the file followed by a character and then writing everything down with >> to the existing file, so it is the same file but plus one character.

This example should only show the intention. It does the procedure for every file with the extension specified in the directory it runs.

I hope you understand what I mean..

Many thanks to all the linux 'experts' in advance

edit: I am afraid this belongs to Programming but I can not delete or move

Very similar; try something likeGo to tldp.org and get the advanced bash guide (not really "advanced", but good).

Thanks a lot

Won't that confuse the decompression algo?

I also was also wondering about this, but with Rar it seems to be no problem.

weird... I'd hate to rely on that continuing to work. Why are you doing this anyway?

To change the MD5 hash without new repacking.

Why would you want to do that ??