Working with the Tape Archive Utility (TAR)

To make a tar file from the directory homework1

$ tar czf homework1.tgz homework1

To check the contents of a tar file called homework1.tgz

$ tar tzf homework.tgz

To extract the contents of a tar file called homework1.tgz

$ tar xzf homework1.tgz

tar or the Tape ARchive utility is a program that is used for combining multiple files into a single file. This is the format that is used to transfer multiple files in the majority of open source project.

Tar files are frequently used to transfer the contents of a directory. The examples on this page assume that you want to transfer all of the files in a directory called homework1 . Further assume the contents of this directory are two files, hello.cpp and Makefile .

$ ls
Makefile  hello.cpp

Files created with tar frequently have the extension .tar. The file homework1.tar is the conventional name used for a tar file containing the directory homework1.

Tar is frequently used in conjunction with compression utilities. GNU zip (gzip) is a common choice for this. A tar file which has been compressed with gzip will frequently have the extension .tgz or even .tar.gz. In this case homework1.tgz or homework1.tar.gz are the conventional names for a tar file containing the directory homework1 which has been compressed with gzip.

This page is a summary, there are other ways that tar can be employed.

The best practice is to work on each project in a folder or directory. For this example the code for a project is located in the directory homework1.

1. Move one directory above the homework1 directory
   1. If you can see the directory you wish to create a tar archive of when you type ls you are in the correct directory.

$ ls 
homework1

1. type the command tar cvzf homework1.tgz homework1
   1. c tells tar to create a tar archive.
   2. v tells tar to show you what it is adding to the archive
   3. z tells tar to use gnuzip to compress the resulting file
   4. f tells tar to write the output to a file, not to the tape devuce
   5. homework1.tgz is the name of the output file.
   6. homework1 is the name of the directory you wish to place in the tar file

$ tar cvzf homework1.tgz homework1

In the following example the user types ls to show that the directory homework1 exists. After that, the tar command to create a tar file is issued. This command is run in verbose mode so each file or directory is listed as it is added to the tar file. The example concludes with a listing of the directory showing that the tar file homework1.tgz has been created.

$ ls
homework1

$ tar cvzf homework1.tgz homework1
homework1/
homework1/Makefile
homework1/hello.cpp

$ ls
homework1  homework1.tgz

To check the contents of a tar file use the following command in the directory containing the tar file.

$ tar tzf homework1.tgz

Note that in this command c has been replaced with t which means table of contents.

$ ls
homework1  homework1.tgz

$ tar tzf homework1.tgz 
homework1/
homework1/Makefile
homework1/hello.cpp

To extract the contents of a tar file

• The tar file should be located in the current working directory.
• Any files matching those in the tar file will be replaced.

In the tar command, c should be replaced with x , which tells tar to extract the contents of the file.

$ tar xzf homework1.tgz

In the following example

• The user types ls to show the contents of the current directory.
• The user issues the tar command to extract the contents of a file.
  • The addition of the v flag tells tar to be verbose, ie show the files as they are extracted.
• The user types ls again to show that the directory homework1 has been created.
• The user types ls -r homework1 to show the files have been extracted in the homework1 directory

$ ls
homework1.tgz

$ tar xvzf homework1.tgz 
homework1/
homework1/Makefile
homework1/hello.cpp

$ ls
homework1  homework1.tgz

$ ls -r homework1
hello.cpp  Makefile

WinSCP has the ability to deal with tar files.

To create a tar file of a directory

• Select the directory
• Right click and select File Custom Commands
• Select Tar/GZip
• 
• You may have to allow a new ssh session
• Provide the name for the tar file.
• 
• Notice the new tar file is located in the current directory.
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