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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’.
Only consider NUL
-terminated file names, instead of files that
terminate in a newline.
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.
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This document was generated by Sergey Poznyakoff on March, 12 2011 using texi2html 1.78.