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Tar archive: how reliable is the supplement?

I noticed that the parameter -ain TAR allows you to add files to an existing archive. How safe is it to create incremental backups of an installed folder? Is there anyone here who can share their experiences?

From the TAR manual:

 -A, --catenate, --concatenate
       append tar files to an archive
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4 answers

Since tar is a Tape Archive , the last file will be physically added to the archive with a header. There is no index table that can cause problems.

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. tar , . , append append, , , .

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, tar , tar-:

makholm@korovyov:~$ dd if=/dev/urandom bs=1M count=1 of=./foo
1+0 records in
1+0 records out
1048576 bytes (1.0 MB) copied, 0.513785 s, 2.0 MB/s
makholm@korovyov:~$ for i in {1..5} ; do tar -rf foo.tar foo ; ls -lh foo.tar ; done
-rw-r--r-- 1 makholm makholm 1.1M 2011-01-22 01:07 foo.tar
-rw-r--r-- 1 makholm makholm 2.1M 2011-01-22 01:07 foo.tar
-rw-r--r-- 1 makholm makholm 3.1M 2011-01-22 01:07 foo.tar
-rw-r--r-- 1 makholm makholm 4.1M 2011-01-22 01:07 foo.tar
-rw-r--r-- 1 makholm makholm 5.1M 2011-01-22 01:07 foo.tar
makholm@korovyov:~$

- , tarball ...

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If you want to do incremental backups, take a look at rsync and what it can do for you in terms of delta transfers and links to previous versions of files ...

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Reliable as your equipment. This is not true.

Also, I'm not sure what it will replace.

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Source: https://habr.com/ru/post/1787039/

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