Compressed Howto

(How to compress and decompress files)

© (2004) Pablo Arés, pablo /at/ math.tifr.res.in

There are many different types of compression techniques for files. Below you have information on how to create, compress and decompress, files in different formats.

gzip

This is the alternative to zip from the GNU software. Files compressed in this format usually have names ending in .gz (or .tgz, see below under tar).
Here is what you have to do to compress or decompress a file with gzip:

Decompresssion. Issue the command:
```
   gunzip file-name.gz
```
where I assume that the full name of the file is file-name.gz
Compresssion. Do the following command:
```
   gzip file-name
```
This will create a file called file-name.gz You can decompress it (retore it to its original form) with gunzip

bzip/bzip2

This is another compressing tool. Files compressed with this utility have names usually ending in .bz2 The commands are similar to the gzip commands above.

Decompression:
```
   bunzip2 file-name.bz
```
Compression:
```
   bzip2 file
```

tar

In a informal way, a tar file is a collection of files put together in a singl file. The tar can be compressed as well. tar files have names ending in .tar, .tar.gz or .tgz (tar plus gzip) or .tar.bz (tar plus bzip2). The commands below will help you to handle tar files; I include the possibility of the file being compressed with gzip or bzip2 as well. For gzip compression I will write file-name.tgz but you can handle with the same commands files ending in tar.gz

Just see the contents of a tar file:

   tar tvf file-name.tar

   tar ztvf file-name.tgz

   tar jtvf file-name.tar.bz2

Extract the files inside a tar archive:

   tar xvf file-name.tar

   tar zxvf file-name.tgz

   tar zxvf file-name.tar.bz2

Extract the files inside a tar archive, but do not overwrite files in the system with the same name:
```
   tar kxvf file-name.tar
```
```
   tar kzxvf file-name.tgz
```
```
   tar kjxvf file-name.tar.bz2
```
Create a tar file from a collection of files:
```
   tar cvf file-name.tar file1 file2 .... filen dir1 dir2 ... dirm
```
You can compress later the tar file with gzip or bzip2

zip

This is similar to tar files, in the sense that a zip file is a collection of files put together. Here are the commands.

List the contents of a zip file:
```
   unzip -l file-name.zip
```
Extract the contents of a zip file:
```
   unzip file-name.zip
```

Create a zip file:

   zip file-name.zip file1 file2 ... filen