Why can't you combine .tar.gz files with cat?

(alexwlchan.net)

8 points | by surprisetalk 1 day ago

5 comments

  • Inityx 1 hour ago
    Nothing says "handwritten" quite like omnipresent groups of 3 bullet points, all with bolded item headers.
    • MayeulC 46 minutes ago
      Yes, this could have been a 5-sentence PSA. I found the article hard to read, with comparatively little content for the length.
      • sevg 33 minutes ago
        Absolutely.

        > My mistake was trying to combine .tar.gz files using cat. gzip plays ball, but tar throws a strop.

        > gzip happily combines the compressed members into a single stream, but when tar tries to read the decompressed stream, it finds the first archive’s EOF marker and stops reading.

        > gzip would be happy to carry on, but tar has given up.

        There was no reason to say this three times consecutively. But when an AI wrote the blog post for you then this is the level of quality HN readers have to put up with.

    • jraph 48 minutes ago
      useless dashes at the middle of sentences maybe?
    • tempfile 39 minutes ago
      Does it actually say anywhere that the article is handwritten?
  • pmontra 38 minutes ago
    Of course you can tar the original tar.gz files in one pass without extracting anything. You keep the boundaries between the source tar.gz but maybe that's not important. You probably won't gzip the output because there is very little to gain anymore.

    But if you want to merge those tar.gz, yes, you have to ungzip them and gzip the final tar. More CPU.

  • edelbitter 41 minutes ago
    Even worse with initcpio and linux kernel decompression choices: You can mix them, and it works.. sometimes.
  • M95D 36 minutes ago
    Oh! I can cat multiple gzip files? Could I do that with "btrfs send | gzip" files?
  • mcapodici 57 minutes ago
    cat is only for concatenation so it won't combine e.g. XML files, images, zip files etc. unless those files can just be splatted together.
    • voidUpdate 49 minutes ago
      which .gz files can, according to the article, but the un-gzipped file contains an eof in the middle for the tape archive, so it stops reading early