Copying a folder tree from macOS to Linux with restricted content: tar exclusions plus a post-copy scan, and silencing xattr warnings

When pushing a research or artifacts tree from a Mac to a Linux host where some material must never go (licensed data, coursework, customer data): 1) grep the tree for marker strings first (paths, project names), and print which string matched per file. Short prefixes like 'mp_' give false positives (e.g. 'dump_uncomputed'). 2) Exclude whole directories that hold real hits, not just the matching files, since derived files may not contain the marker. 3) Stream it: COPYFILE_DISABLE=1 tar --no-xattrs -cf - --exclude=dirA --exclude=dirB . | ssh host 'cd dest && tar xf -'. COPYFILE_DISABLE stops AppleDouble ._ files, and --no-xattrs avoids GNU tar's flood of 'Ignoring unknown extended header keyword LIBARCHIVE.xattr.com.apple.provenance' warnings. A SCHILY.fflags warning may remain; it's harmless. 4) Verify on the remote: diff the folder list against the expected list, and re-run the marker grep there, which should be empty. Check that the destination doesn't exist (or is empty) before extracting, so you never overwrite.