Lab
A Cloud Guru

Archiving and Compressing

In this lab, we'll create tar archives from various sources, and then use the compression tools to create compressed versions of those archives, comparing compression algorithms' apparent merits. We'll also investigate the contents of compressed archives as well as uncompress them back to disk, either in their entirety or extracting a file from a compressed archive.

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Path Info

Level

Beginner

Duration

45m

Published

Nov 27, 2019

Challenge

Use the `tar` Command to Create an Archive, View It, and Extract It
Check the size of the files we're looking to archive:
```
du -sh /usr/share/doc/packages
```
Note its size (around 100M).

Create an archive:
```
tar -cf packagedocs.tar /usr/share/doc/packages
```
Run ls -l on the file:
```
ls -l *.tar
```
We should see the one we just created.

Check its size:
```
du -sh packagedocs.tar
```
Note its size. It isn't too much smaller than the original.

Let's look at the files in it:
```
tar -tf packagedocs.tar
```
Notice there isn't a / at the beginning of any of them.

Get more information:
```
tar -tvf packagedocs.tar
```
Extract the file:
```
tar -xvf packagedocs.tar
```
This will create a usr/ directory.

Check the sizes:
```
du -sh /usr/share/doc/packages ./usr
```
We should see that the sizes match.

Compare the sizes:
```
du -sh /usr/share/doc/packages/ ./usr packagedocs.tar
```
We'll see they're essentially the same.

Create a compressed archive file with gzip:
```
tar -czvf packagedocs.tar.gz /usr/share/doc/packages
```
Compare the sizes:
```
du -sh /usr/share/doc/packages/ ./usr packagedocs.*
```
We should see the .gz file is significantly smaller. (It will be around 30M.)

Create a compressed archive file with bzip:
```
tar -cjvf packagedocs.tar.bz2 /usr/share/doc/packages
```
Compare the sizes:
```
du -sh /usr/share/doc/packages/ ./usr packagedocs.*
```
We should see the .bz2 file is only slightly smaller than the .gz file (around 20M vs. 30M).

Create a compressed archive file with xz:
```
tar -cJvf packagedocs.tar.Z /usr/share/doc/packages
```
Compare the sizes:
```
du -sh /usr/share/doc/packages/ ./usr packagedocs.*
```
We should see the .Z file is ever-so slightly smaller than the .bz2 file.

Delete the directory:
```
rm -rf ./usr
```
Make sure it's gone:
```
ls -ld ./usr
```
We should see it's no longer there.

List the contents of the .gz archive:
```
tar -tzvf packagedocs.tar.gz
```
Search for "wicked":
```
tar -tzvf packagedocs.tar.gz | grep wicked
```
This will show us everything that includes "wicked".

Extract specific directory name:
```
tar -xzvf packagedocs.tar.gz usr/share/doc/packages/wicked/samples
```
Verify it happened:
```
tree -d ./usr
```
Note: You may need to install tree by running sudo zypper install tree.

We should see the tree showing it extracted the directory.

Extract the entire archive:
```
tar -xzvf packagedocs.tar.gz
```
Verify it happened:
```
du -sh ./usr
```
We should see its size is around 100M.
Challenge

Use the Available Compression Utilities to Act on Files, Groups of Files, and Directories
Copy packagedocs.tar to gziptest.tar:
```
cp packagedocs.tar gziptest.tar
```
Copy packagedocs.tar to bzip2test.tar:
```
cp packagedocs.tar bzip2test.tar
```
Verify they're there:
```
du -sh *zip*
```
We should see them both.

Compress gziptest.tar:
```
gzip gziptest.tar
```
Compress bzip2test.tar:
```
bzip2 bzip2test.tar
```
Check what's there:
```
du -sh *zip*
```
We should see there aren't any .tar files, and both files there are significantly smaller than they were before.

Now, let's use the wrong utility on the right file:
```
bunzip2 gziptest.tar.gz
```
We should see a message saying it is not a bzip2 file and won't work.

Instead, run the following:
```
gunzip gziptest.tar.gz
```
Now, do the same thing with bunzip2:
```
bunzip2 bzip2test.tar.bz2
```
See what's there:
```
du -sh *zip*
```
We'll see the .tar files are back, and they are the original, larger sizes.

If you want to keep the original file, run:
```
gzip -k gziptest.tar
```
See what's there now:
```
du -sh *zip*
```
We can see we kept the original file and have a compressed file.

Author

A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

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