Also a Central Asian stringed musical instrument which looks somewhat like a lute. It became popular in Iran during the 19th century.

The tar is a well known traditional instrument in Uzbekistan, Azerbaijan, Armenia, Tajikistan, and, of course, Iran.

tar - UNIX Command

The UNIX command tar stands for Tape ARchive and is used to create, add files to, and extract files from, a 'tape archive'. In this context, a tape archive can be any kind of physical storage media, (e.g. tape, CD). It can also be an archive file, ('tar file), commonly used when transferring data via FTP . Finally, the archive can even be nothing at all, (see second example below).

As with all UNIX commands, a complete description of the command as it can be used on your UNIX system can be obtained thus:

% man tar

Having said that, here's a couple of tips related to the use of the tar command that I've found useful:


% tar cf - filename | gzip -9 > filename.tar.gz

This command creates a gzipped tarfile. It's helpful when you have a large amount of data to archive, but don't have enough disk space left to create an uncompressed tarfile as an intermediate stage.

What's it doing? Well, the tar command archives the given filename into STDOUT. This is piped as the input into the gzip command, (of course, you can substitute your favourite file compression command). Finally, the output of the gzip operation is redirected to the file filename.tar.gz.


% cd fromdir ; tar cf - . | (cd todir ; tar xfBp -)

This example uses the tar command to copy a directory hierarchy from one place, (fromdir), to another, (todir).

What's it doing? Well, first it moves to the source directory. The subsequent 'tar cf' command indicates that a tar file will be created. The name of the file is given as '-', i.e. STDOUT. The '.' indicates all files below fromdir are to be archived.

Next, the output, i.e. STDOUT, from 'tar cf' is piped as STDIN into the next command pair. The parentheses ensure that we have moved to the target directory before the second 'tar' command extracts the tar file. If you want to know the significance of the 'B' and 'p' modifiers, 'man tar' should reveal all!

Tar

Tar seems to be such a simple and ordinary thing, yet few products have matched it's importance and impact on manufacturing evolution.

History of Tar

When people first began to heat coal to get coke for furnaces, the stiff black liquid that came from it was thought to be valueless. It was called "coal tar," and was thrown away. Now, more than 200,000 by-products are made from this tar that are used everyday.

The first use of coal tar was as a fuel. Later on, it was used as a protective coating on wood and ropes. Tar is waterproof, as well as wear-resistant. Finally, it was discovered that other useful substances could be made from the tar. When tar was heated and distilled, different oils were obtained. One of these was used for a long time as a substitute for turpentine.

Then, in 1856, a 17-year old chemistry assistant in England, William Henry Perkin, accidentally discovered that certain dyes, called aniline, could be made from coal tar. This opened a whole new world of industry.

After that point, chemists began to take a closer look at tar, and noticed just how useful it could be.

By-Products and Their Creation

How are various products obtained from tar? The process is called distillation. The tar is boiled in big ovens that have bent tubes leading from them. The released gasses are separated and collected, as are the liquids. (for a thorough description of distillation, visit the node) Coal tar itself contains a little of everything(2.com). As it is distilled again, different substances are drawn off. The "pitch" that remains is the tar we are familiar with in tar shingles, tar-paper roofing, and asphalt on the streets.

Most of the colors now used for dyes and printing inks are made from coal tar. Carbolic acid, used as antiseptic in hospitals, comes from tar. Aspirin, saccharin (which is 550 times as sweet as cane sugar), and nylon all come from tar in some form. (Note- today, most of the chemicals for aspirin that came from tar are synthesized in a lab) Also, the entire modern plastics industry is based on tar! Mothballs, artificial food flavorings, asphalt, carbon paper, etc. all come from tar in some form. So you see that in a lump of coal, and the tar inside, we have the source of thousands of products we use every day.



Node your homework/school projects

Don't lose a sheep for a halfpennyworth of tar : tar is used to mark sheep.

A jack tar ; a sailor.

The 1811 Dictionary of the Vulgar Tongue.

Tar (?), n. [Abbrev. from tarpaulin.]

A sailor; a seaman.

[Colloq.]

Swift.

 

© Webster 1913.


Tar, n. [OE. terre, tarre, AS. teru, teoru; akin to D. teer, G. teer, theer, Icel. tjara, Sw. tjara, Dan. tiaere, and to E. tree. 63. See Tree.]

A thick, black, viscous liquid obtained by the distillation of wood, coal, etc., and having a varied composition according to the temperature and material employed in obtaining it.

Coal tar. See in the Vocabulary. -- Mineral tar Min., a kind of soft native bitumen. -- Tar board, a strong quality of millboard made from junk and old tarred rope. Knight. -- Tar water. (a) A cold infusion of tar in water, used as a medicine. (b) The ammoniacal water of gas works. -- Wood tar, tar obtained from wood. It is usually obtained by the distillation of the wood of the pine, spruce, or fir, and is used in varnishes, cements, and to render ropes, oakum, etc., impervious to water.

 

© Webster 1913.


Tar, v. t. [imp. & p. p. Tarred (?); p. pr. & vb. n. Tarring.]

To smear with tar, or as with tar; as, to tar ropes; to tar cloth.

To tar and feather a person. See under Feather, v. t.

 

© Webster 1913.

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