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bsdtar has a -k (Do not overwrite existing files) option, which avoids changing the contents of any existing files, but it still overwrites the file info (e.g. permissions) with what is in the archive. Is there a way to make bsdtar completely skip overwriting existing files leaving file info intact the same way the --skip-old-files option works in GNU tar?

Here is a script that demonstrates the problem:

#!/usr/bin/env bash

echo -e "\nCreate an archive with normal files"
rm -rf test-tar
mkdir test-tar
echo "TEST CONTENTS 1" > test-tar/1.txt
echo "TEST CONTENTS 2" > test-tar/2.txt
ls -la test-tar
bsdtar -czf test.tgz test-tar

echo -e "\nChange contents and permissions of one of the files"
echo "MORE CONTENTS" >> test-tar/2.txt
chmod 000 test-tar/2.txt
ls -la test-tar

echo -e "\nUntar the archive with -k (Do not overwrite existing files). The file contents are intact, but the file permissions have changed"
bsdtar -xzkf test.tgz
ls -la test-tar
cat test-tar/2.txt

echo -e "\nUntar the archive without -k"
bsdtar -xzf test.tgz
ls -la test-tar
cat test-tar/2.txt

Here is the script output:

Create an archive with normal files
total 16
drwxr-xr-x   4 rbrainard  wheel  136 Nov 29 17:53 .
drwxr-xr-x  14 rbrainard  wheel  476 Nov 29 17:53 ..
-rw-r--r--   1 rbrainard  wheel   16 Nov 29 17:53 1.txt
-rw-r--r--   1 rbrainard  wheel   16 Nov 29 17:53 2.txt

Change contents and permissions of one of the files
total 16
drwxr-xr-x   4 rbrainard  wheel  136 Nov 29 17:53 .
drwxr-xr-x  14 rbrainard  wheel  476 Nov 29 17:53 ..
-rw-r--r--   1 rbrainard  wheel   16 Nov 29 17:53 1.txt
----------   1 rbrainard  wheel   30 Nov 29 17:53 2.txt

Untar the archive with -k (Do not overwrite existing files). The file contents are intact, but the file permissions have changed
total 16
drwxr-xr-x   4 rbrainard  wheel  136 Nov 29 17:53 .
drwxr-xr-x  14 rbrainard  wheel  476 Nov 29 17:53 ..
-rw-r--r--   1 rbrainard  wheel   16 Nov 29 17:53 1.txt
-rw-r--r--   1 rbrainard  wheel   30 Nov 29 17:53 2.txt
TEST CONTENTS 2
MORE CONTENTS

Untar the archive without -k
total 16
drwxr-xr-x   4 rbrainard  wheel  136 Nov 29 17:53 .
drwxr-xr-x  14 rbrainard  wheel  476 Nov 29 17:53 ..
-rw-r--r--   1 rbrainard  wheel   16 Nov 29 17:53 1.txt
-rw-r--r--   1 rbrainard  wheel   16 Nov 29 17:53 2.txt
TEST CONTENTS 2

My bsdtar version is 3.3.2.

1

It turned out that this is a bug. I cross-posted it to libarchive-discuss and one of the maintainers responded as such. Filed an issue at: https://github.com/libarchive/libarchive/issues/972

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