this post was submitted on 29 Jun 2024
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How to reliably(!) exclude files from a list in tar? (feddit.de)
submitted 3 months ago* (last edited 3 months ago) by MonkderDritte@feddit.de to c/linux@lemmy.ml
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This is bothering me for years now, my backup script always takes everything with it, taking forever to finish.

I initially used the --exclude option, but this is rather restrictive, cluttered the script and still had the excluded directories.
Then i discovered -X/--exclude-from but same result here, weird globbing and still fails.
So i hacked a negative list via fd's --ignore-file and tar -T/--files-from together. But tar still includes files and directories not on the fucking files.tmp.

So i'm not sure if it is a bug in Arch's GNU tar or if it's maybe a parameter in the wrong position, tar can be removed there. This is my current code

# tar -cf - -X "$XDG_CONFIG_HOME"/backup/ignore "$INPUT" -P

fd . -Hi --ignore-file "$XDG_CONFIG_HOME"/backup/ignore "${INPUT}" > "$_tmpfile"
tar -cf - --verbatim-files-from --files-from="$_tmpfile" -P \
	|pv -tapes "$_fssize" \
	|compress >"${OUTPUT}.$_ext"

INPUT is $HOME in this case.

And if anyone has a solution that works on busybox tar as well...

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[–] lurch@sh.itjust.works 9 points 3 months ago

--exclude works reliable for me. can you give us an example of an --exclude and the file name that tar outputs when adding it?

[–] kbal@fedia.io 4 points 3 months ago* (last edited 3 months ago) (1 children)

I don't know what fd does, but at a guess maybe what you're missing is that tar includes all the files in directories you give it? So if you exclude 'foo/bar' but include 'foo' then foo/bar will be in your tar file.

What I do is basically tar cf `ls ~ | grep -v $files_to_exclude` but if you want to exclude something that isn't a top-level directory you'd need to get slightly more fancy.

[–] kbal@fedia.io 1 points 3 months ago* (last edited 3 months ago)

...more fancy such as using tar -X, which works for me. I'd never actually tried it before. The 'weird globbing' it uses is regular expressions, which are worth learning how to use. Run grep "$expression" $_tmpfile where $expression is a line from your exclude file to see which files it's going to match and exclude.

[–] MonkderDritte@feddit.de 2 points 3 months ago* (last edited 3 months ago)

Thanks!

I save it for now, until i work on it again. Possibly the wildcards thing. And that tar includes files of folders given too, from someone else (how to work with that).

[–] TCB13@lemmy.world -4 points 3 months ago

How to reliably(!) exclude files from a list in tar?

You delete the entire file because the format and tools are hard to deal with for basic operations like this one. :)

Just kidding... but we know there's some truth to it.