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Tar Formats |
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WinTar can read and extract most tar archives. However, it only writes POSIX-standard ustar and pax interchange formats. All tar formats store each entry in one or more 512-byte records. The first record is used for file metadata, including filename, timestamp, and mode information, and the file data is stored in subsequent records. Later variants have extended this by either appropriating undefined areas of the header record, extending the header to multiple records, or by storing special entries that modify the interpretation of subsequent entries. |
gnutarWinTar can read and extract GNU-format tar archives. It currently supports the most popular GNU extensions, including modern long filename and linkname support, as well as atime and ctime data. WinTar does not support multi-volume archives, nor the old GNU long filename format. It can read GNU sparse file entries, including the new POSIX-based formats, but cannot write GNU sparse file entries. |
ustarWinTar can both read and write this format. This format has the following limitations: o Device major and minor numbers are limited to 21 bits. Nodes with larger numbers will not be added to the archive. o Path names in the archive are limited to 255 bytes. (Shorter if there is no / character in exactly the right place.) o Symbolic links and hard links are stored in the archive with the name of the referenced file. This name is limited to 100 bytes. o Extended attributes, file flags, and other extended security information cannot be stored. o Archive entries are limited to 2 gigabytes in size. Note that the pax interchange format has none of these restrictions. |
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WinTar can also read a variety of commonly-used extensions to the basic tar format. In particular, it supports base-256 values in certain numeric fields. This essentially removes the limitations on file size, modification time, and device numbers. The first tar program appeared in Seventh Edition Unix in 1979. The first official standard for the tar file format was the "ustar" (Unix Standard Tar) format defined by POSIX in 1988. POSIX.1-2001 extended the ustar format to create the "pax interchange" format. |
Related file formats
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