How to destroy your OS with tar

Re:How to destroy your OS with tar by doublerabbit on Friday May 24, 2024 @01:02PM (#40468132)

I'm kind of annoyed that tar doesn't back up directories starting with a period unless you throw in a command flag.

I wish I knew this before taking a backup and reformatting.

Always test your backups I guess..

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Re:How to destroy your OS with tar by vorakl on Friday May 24, 2024 @06:39PM (#40471129)

This is an interesting one. What was the version of tar? Was it gnu tar? I wonder, how did you create that archive?

I'm asking this because I was trying to reproduce the same situation and everything seems to be working fine:

  $ tar -C /tmp/root3 -cvf test.tar .
  ./
  ./.config/
  ./.config/test
  ./.local/
  ./var/
  ./var/db/
  ./var/db/xbps/

or even like this

  $ tar -cvf test2.tar root3/
  root3/
  root3/.config/
  root3/.config/test
  root3/.local/
  root3/var/
  root3/var/db/
  root3/var/db/xbps/

No special options were needed. But, if I do it this way, then, there are definitely missing all dot directories:

  $ tar -cvf test2.tar root3/*
  root3/usr/
  root3/usr/bin/
  root3/usr/bin/xbps-uunshare

But this problem is not a tar's problem. That's only because "*" mask doesn't match dot files:

  $ echo root3/*
  root3/usr root3/var

For that purpose, you need to clearly add a dot:

  $ echo root3/.*
  root3/.config root3/.local

Thus, the solution might be

  $ tar -cvf test2.tar root3/.* root3/*
  root3/.config/
  root3/.config/test
  root3/.local/
  root3/usr/
  root3/usr/bin/

But, I'd rather stick to "-C dir/" option instead of relying on "*" mask in this case.

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Re:How to destroy your OS with tar by doublerabbit on Friday May 24, 2024 @08:27PM (#40471688)

   tar -cvf mytar.tar /home/myuser/*

Was definitely the syntax I ran. I'm on FreeBSD so just tar.

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Re:How to destroy your OS with tar by vorakl on Friday May 24, 2024 @10:39PM (#40472238)

Then, this explains why. BTW, this is an expected Shell behavior, specified in the POSIX standard:

  If a filename begins with a <period> ( '.' ), the <period> shall be explicitly
  matched by using a <period> as the first character of the pattern or immediately
  following a <slash> character. The leading <period> shall not be matched by:
   * The <asterisk> or <question-mark> special characters

https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V...

Interesting fact about the FreeBSD tar's origins:

  GNU tar was included as the standard system tar in
  FreeBSD beginning with FreeBSD 1.0.
  This is a complete re-implementation based
  on the libarchive(3) library. It was first released with
  FreeBSD 5.4 in May, 2005.

https://man.freebsd.org/cgi/man.cgi?query=tar

My personal journey with FreeBSD began with version 5.3 (the first stable release on the 5th branch) in November 2004. I was completely unaware of such a significant tar change, and apparently I didn't care at the time. However, the entire 5th branch has been so revolutionary compared to the 4th branch that this change is just a drop in the bucket ;)

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