Why does tar –exclude=“.*” create an empty archive

If you want to exclude an entire directory, your pattern should match that directory, not files within it. Use --exclude=/data/sub1 instead of --exclude='/data/sub1/*'

Be careful with quoting the patterns to protect them from shell expansion.

See this example, with trouble in the final invocation:

$ for i in 0 1 2; do mkdir -p /tmp/data/sub$i; echo foo > /tmp/data/sub$i/foo; done
$ find /tmp/data
/tmp/data
/tmp/data/sub2
/tmp/data/sub2/foo
/tmp/data/sub0
/tmp/data/sub0/foo
/tmp/data/sub1
/tmp/data/sub1/foo
$ tar -zvcf /tmp/_data.tar /tmp/data --exclude='/tmp/data/sub[1-2]'
tar: Removing leading `/' from member names
/tmp/data/
/tmp/data/sub0/
/tmp/data/sub0/foo
$ tar -zvcf /tmp/_data.tar /tmp/data --exclude=/tmp/data/sub[1-2]
tar: Removing leading `/' from member names
/tmp/data/
/tmp/data/sub0/
/tmp/data/sub0/foo
$ echo tar -zvcf /tmp/_data.tar /tmp/data --exclude=/tmp/data/sub[1-2]
tar -zvcf /tmp/_data.tar /tmp/data --exclude=/tmp/data/sub[1-2]
$ tar -zvcf /tmp/_data.tar /tmp/data --exclude /tmp/data/sub[1-2]
tar: Removing leading `/' from member names
/tmp/data/
/tmp/data/sub2/
/tmp/data/sub2/foo
/tmp/data/sub0/
/tmp/data/sub0/foo
/tmp/data/sub2/
tar: Removing leading `/' from hard link targets
/tmp/data/sub2/foo
$ echo tar -zvcf /tmp/_data.tar /tmp/data --exclude /tmp/data/sub[1-2]
tar -zvcf /tmp/_data.tar /tmp/data --exclude /tmp/data/sub1 /tmp/data/sub2

The shell expands wildcards in arguments, so most applications don't need to perform any wildcard expansion. However tar's exclude list does support wildcards, which happen to match the wildcards supported by traditional shells. Beware that there may be slight differences; for example tar doesn't distinguish * and ** like ksh, bash and zsh can. With tar, * can match any character including /, so for example */.svn excludes a file called .svn at any level of the hierarchy. You can use tar --no-wildcards-match-slash in which case * doesn't match directory separators.

For example, excluding /home/me/websites/*log.txt excludes /home/me/websites/log.txt, /home/me/websites/foo-log.txt and /home/me/websites/subdir/log.txt. Excluding /home/me/websites/**/vendor excludes /home/me/websites/one/vendor and /home/me/websites/one/two/vendor but not /home/me/websites/vendor. With the --no-wildcards-match-slash option, /home/me/websites/*log.txt does not exclude /home/me/websites/subdir/log.txt and /home/me/websites/**/vendor does not exclude /home/me/websites/one/two/vendor.

tar … --exclude='/home/www-data/sites/*include' … excludes the files and directories under /home/www-data/sites whose name ends with include. You might get away without the quotes, but not if you write --exclude /home/www-data/sites/*include (because then the shell would expand the wildcards before tar can see them) or if you use a shell that signals an error on non-matching wildcards (e.g. zsh in its default — and recommended — configuration).

The option --exclude-from requires a file name. The file must contain one pattern per line. Do not confuse --exclude (followed by a pattern) and --exclude-from (followed by the name of a file containing patterns).