Comment by sedatk
5 hours ago
> the fact that you cannot get a valid bzip2 file by cat-ing 2 compressed files
TIL. Now that's why gzip has a file header! But, tar.gz compresses even better, that's probably why it hasn't caught on.
5 hours ago
> the fact that you cannot get a valid bzip2 file by cat-ing 2 compressed files
TIL. Now that's why gzip has a file header! But, tar.gz compresses even better, that's probably why it hasn't caught on.
tar packs multiple files into one. If you concatenate two gzipped files and unzip them, you just get a concatenated file.
Ah okay, I thought gzip would support decompressing multiple files that way.
How it works is, if you have two files foo.gz and bar.gz, and cat foo.gz bar.gz > foobar.gz, then foobar.gz is a valid gzip file and uncompresses to a single file with the contents of foo and bar.
It’s handy because it is very easy to just append stuff at the end of a compressed file without having to uncompress-append-recompress. It is a bit niche but I have a couple of use cases where it makes everything simpler.
tar supports that types of concatenation, so you can concatenate tar.gz files, and unpack them all into separate files