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发现奇怪的 TAR 档案格式

tag-icon • tag-icon linux tar archiving
发现奇怪的 TAR 档案格式

我有一些可以用以下方式提取的文件tar：
tar -tvf attachment.tar
但是当我用以下方式测试时，file我得到了以下结果：
attachment.tar: uuencoded or xxencoded text, ASCII text, with CRLF line terminators

该文件的第一个字节begin 644 RST.0486.20220814-0300.tar
如下：

M0U4P-#@V+D%)6%-C86XN,C`R,C`X,30M,#,P,"YT>'0`````````````````
M````````````````````````````````````````````````````````````
M`````````````#$P,#8T-"``,#`P,#`P(``P,#`P,#`@`#`P,#`P,3(P-S4S
M(#$T,C<V,3$V-C0T(#`Q-34R,0`@,```````````````````````````````
M````````````````````````````````````````````````````````````
M``````````````````````````````````````````!U<W1A<@`P,')O;W0`
M````````````````````````````````````<WES=&5M````````````````
M```````````````````P,#`P,#`@`#`P,#`P,"``````````````````````
M````````````````````````````````````````````````````````````
M````````````````````````````````````````````````````````````
M````````````````````````````````````````````````````````````
M```````````````````````**BHJ*BHJ*B`@1&%T92`@*BHJ*BHJ*BH*<WEM

该库也无法将其识别为 tar 文件：
https://github.com/imagekit-developer/imagekit-ios/wiki/MimeType
bytes[257...261] == [0x75, 0x73, 0x74, 0x61, 0x72]

我如何才能找到该档案的确切类型和格式？

答案1

您搜索的命令是

uudecode attachment.tar

这将转换 uuencoded tar 文件，其名称RST.0486.20220814-0300.tar取自原始文件。

此格式的用途是仅通过 ASCII 格式的“媒体”二进制文件进行传输。

答案2

确切的类型和格式就是字面上file的意思——它是一个 UUEncoded 文件。这种编码在 MIME/Base64 出现之前的早期网络上很常见（即在电子邮件有“附件”之前）。

UUEncode 只是一种传输格式，实际的 TAR 存档位于其中（类似于 GZip 中包含 TAR）。使用将uudecode数据转换回二进制格式，然后然后您可能有一个常规的 TAR 档案。Linux 在“sharutils”包中有此程序，而对于 Windows，您可以使用 UUDeview 或 UUDWin32。

通常，邮件客户端应该自动解码传输编码，或者至少将文件保存为“attachment.tar.uu”（尽管我认为后者没有真正的惯例）。

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