要像 tar 一样获取新的 zip 文件，我是否必须在执行rm foo.zip之前执行zip？
$ mkdir foo; touch foo/bar
$ zip -r foo.zip foo
adding: foo/ (stored 0%)
adding: foo/bar (stored 0%)
$ rm foo/bar; touch foo/baz
$ zip -r foo.zip foo
adding: foo/ (stored 0%)
adding: foo/baz (stored 0%)
$ unzip -l foo.zip
Archive: foo.zip
Length Date Time Name
--------- ---------- ----- ----
0 2011-10-27 07:49 foo/
0 2011-10-27 07:49 foo/bar
0 2011-10-27 07:49 foo/baz
--------- -------
0 3 files