6.3.1 NUL-Terminated File Names

The --null option causes --files-from=file-of-names (-T file-of-names) to read file names terminated by a NUL instead of a newline, so files whose names contain newlines can be archived using --files-from.

--null

Only consider NUL-terminated file names, instead of files that terminate in a newline.

--no-null

Undo the effect of any previous --null option.

The --null option is just like the one in GNU xargs and cpio, and is useful with the -print0 predicate of GNU find. In tar, --null also disables special handling for file names that begin with dash.

This example shows how to use find to generate a list of files larger than 800K in length and put that list into a file called long-files. The -print0 option to find is just like -print, except that it separates files with a NUL rather than with a newline. You can then run tar with both the --null and -T options to specify that tar gets the files from that file, long-files, to create the archive big.tgz. The --null option to tar will cause tar to recognize the NUL separator between files.

     $ find . -size +800 -print0 > long-files
     $ tar -c -v --null --files-from=long-files --file=big.tar

The --no-null option can be used if you need to read both NUL-terminated and newline-terminated files on the same command line. For example, if flist is a newline-terminated file, then the following command can be used to combine it with the above command:

     $ find . -size +800 -print0 |
       tar -c -f big.tar --null -T - --no-null -T flist

This example uses short options for typographic reasons, to avoid very long lines.

GNU tar is able to automatically detect NUL-terminated file lists, so it is safe to use them even without the --null option. In this case tar will print a warning and continue reading such a file as if --null were actually given:

     $ find . -size +800 -print0 | tar -c -f big.tar -T -
     tar: -: file name read contains nul character

The null terminator, however, remains in effect only for this particular file, any following -T options will assume newline termination. Of course, the null autodetection applies to these eventual surplus -T options as well.