`tar` - an archiving utility

tar -c|-x|-t [-v] [-O] [-C DIR] -f ARCHIVE [FILE...]

Options you will use

-c: create an archive
-x: extract files
-t: list the contents
-v: verbose (with -t: mode, owner, size, name)
-f FILE: the archive file
-O: extract to stdout
-C DIR: change to DIR first
-z, --gzip: Filter through gzip: .tar.gz / .tgz.
-j, --bzip2: Filter through bzip2.
-J, --xz: Filter through xz.
-a, --auto-compress: Pick the compression from the archive suffix.
-h, --dereference: Follow symlinks: archive the files they point to, not the links.
-p, --preserve-permissions: Extract the permissions exactly (the default for root).
--exclude=PATTERN: Leave out files matching PATTERN.
-r, --append: Append files to an archive.
--strip-components=N: Drop the first N path components when extracting.
--numeric-owner: Use numeric user and group ids.

$ tar -tf image.tar

list what docker save produced

$ tar -tvf blobs/sha256/<layer>

list a single layer, whiteouts (.wh.) included

$ tar -xOf blobs/sha256/<layer> app/.env

print one file from a layer

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