Problems and Limitations
The original tar format was created in the early days of UNIX, and despite current widespread use, many of its design features are considered dated.
Many old tar implementations (such as GNU tar) do not record extended attributes (xattrs) or ACLs. In 2001, star introduced support for ACLs and extended attributes. Later, major Linux distributions created their own patched versions of GNU tar that fully support ACL.
In 1997, Sun proposed a method for adding extensions to the tar format. This method was later accepted for the POSIX.1-2001 standard. This format is known as extended tar-format or pax-format. The new tar format allows you to add any type of vendor-tagged vendor-specific enhancements. The following enhancement tags are defined by the POSIX standard:
- all three time stamps of a file in arbitrary resolution (most implementations use nanosecond granularity)
- path names of unlimited length and character set coding
- symlink target names of unlimited length and character set coding
- user and group names of unlimited length and character set coding
- files with unlimited size (the historic tar format is limited to 8 GB)
- userid and groupid without limitation (this historic tar format was is limited to a max. id of 2097151)
- a character set definition for path names and user/group names
In 2001, Star became the first tar to support the new format. In 2004, GNU tar supported the new format.
Other formats have been created to address the shortcomings of tar. These formats include DAR (Disk Archiver) and rdiff-backup (see Duplicity branch of the Savannah software site). However, these formats are not part of any official standard.
Read more about this topic: Tar (computing)
Famous quotes containing the words problems and, problems and/or limitations:
“I believe that if we are to survive as a planet, we must teach this next generation to handle their own conflicts assertively and nonviolently. If in their early years our children learn to listen to all sides of the story, use their heads and then their mouths, and come up with a plan and share, then, when they become our leaders, and some of them will, they will have the tools to handle global problems and conflict.”
—Barbara Coloroso (20th century)
“The truth of the thoughts that are here set forth seems to me unassailable and definitive. I therefore believe myself to have found, on all essential points, the final solution of the problems. And if I am not mistaken in this belief, then the second thing in which the value of this work consists is that it shows how little is achieved when these problems are solved.”
—Ludwig Wittgenstein (1889–1951)
“No man could bring himself to reveal his true character, and, above all, his true limitations as a citizen and a Christian, his true meannesses, his true imbecilities, to his friends, or even to his wife. Honest autobiography is therefore a contradiction in terms: the moment a man considers himself, even in petto, he tries to gild and fresco himself.”
—H.L. (Henry Lewis)