When I pass the "z" flag to tar when creating an archive, and the files grow while the archive is being created, I get an invalid gzip output: $ tar --version bsdtar 1.2.53 - libarchive 1.3.1 $ tar zcf mybackup.tar.gz mybackup/ # files in mybackup/ are growing tar: Truncated write; file may have grown while being archived. tar: Truncated write; file may have grown while being archived. tar: GZip compression failed $ gzip -dc mybackup.tar.gz > /dev/null gzip: ../mybackup.tar.gz: unexpected end of file gzip: ../mybackup.tar.gz: uncompress failed However, it appears to work fine on: $ tar --version bsdtar 1.2.53 - libarchive 1.2.53 Regards, Jeff Davis