tar

Tar is used to create a single (tar) file that contains multiple files. The tar command archives and extracts files to and from a single file called a tarfile. A set of files can be "tarred" to create a single tar file, and a tar file can be "untarred" to extract the individual files.

Creating a tar file

Option 1: The not so safe way to create a tar file (use Option 2 instead)
To create a tar file, use the cvf command line option, list the name of the resulting tar file, and then list the files to put in the tar file:
```
	% ls
	README  btree.c   btree.h  main.c
	% tar cvf  hw10.tar  main.c  btree.c   btree.h  README
	% ls
	README  btree.c   btree.h  hw10.tar main.c
```
In this example, the btree.h, btree.c, main.c and README files are combined into a single tarfile named hw10.tar
WARNING: be sure to include the destination tarfile name argument to tar (in this example it is the hw10.tar argument), otherwise tar will overwrite the contents of one of the source file arguments with the tarfile. In fact, before you create a tarfile, it is a good idea to create copies of these files in another directory. One way to do this is to create a subdirectory "handin" and copy the files there before taring:
```
        % mkdir handin
        % cp *.[ch] handin/.
```
Next, create a tarfile. If you forget the destination file in the tar command and overwrite a source file with garbage, you have a copy in handin of the original file.
Option 2: A better (safer) way to create a tar file.
You can tar the entire contents of a directory rather than listing each individual file as an argument to tar. For example, create a handin directory, cp all the files to tar up into this directory, and tar up the file:
```
	% mkdir handin
	% cp *.[ch] handin/.
	% cp README handin/.
	% tar cvf hw10.tar handin
```
If you forget to list the tar file target (hw10.tar) in the tar command, tar will exit with an error message.

Extracting files from a tar file

To extract files from a tar file, use the x command line arguments to tar:

	% tar xvf hw10.tar
	handin/
	handin/README
	handin/btree.c
	handin/btree.h
	handin/main.c

To see the set of files in a tar file

To list the contents of a tar file, use the tf (or tvf) command line argument:

	% tar tf hw10.tar
	handin/
	handin/README
	handin/btree.c
	handin/btree.h
	handin/main.c

For more information look at the man page for tar: % man tar