Long story short: I have big (700+ GB) .tar.bz2 archive and I wanted to decompress it. It is stored on very slow HDD, so it took my computer about 110 hours nonstop working to get 92% of data. But then I accidentally close the terminal with unarchiving process.
If decompressing process was stopped can it continue from the breakpoint or skip already unzipped files or skip some offset?
Yes, it is possible in principle since a bzip2 file consists of independent blocks, each of which starts with a specific marker that you can search for. Also a tar file consists of independent blocks for each file, for which you should be able to find headers on some 512-byte boundaries.
You would need to write your own code to poke around and try to find out where you left off, assuming you know what the last file extracted was. Then you could continue to decompress from there.