C2110 UNIX and programming 13th Lesson -1C2110
UNIX and programming
Petr Kulhánek, Jakub Štěpán
kulhanek@chemi.muni.cz
National Centre for Biomolecular Research, Faculty of Science
Masaryk University, Kotlářská 2, CZ-61137 Brno
CZ.1.07/2.2.00/15.0233
13th Lesson
C2110 UNIX and programming 13th Lesson -2-
Contents
 Data compression
• Lossless versus lossy compression
• Archives
• Archive types, creation, extraction
 Source code compilation
• Archive extraction
• Configuration
• Compilation
• Installation
 Commands
• gzip, bunzip, bzip2, bunzip2, zip, unzip, tar
C2110 UNIX and programming 13th Lesson -3-
Compression
 Lossless
 Lossy
C2110 UNIX and programming 13th Lesson -4-
Compression
Compression is process that reduces data (file) size. It is done by searching for redundant
or unimportant information in data, these are then saved more efficiently. According to
algorithm used compression may be devided into groups:
• Lossy compression – unimportant information is lost unreversibly, this is often
tolerated by graphical or voice data compression.
• Lossless compression – no information is lost, compressed data may recover to original
state, compression rate is much lower.
Compressed data recovery is decompression.
Compression rate denotes compression quality. It is ration of original data size (in bytes)
and compressed data size.
C2110 UNIX and programming 13th Lesson -5Lossy
compression
Applications for lossy compression and decompression:
• mplayer
• mencoder
• convert (Image Magick)
• and more ...
Conversion of image in PNG format (Portable Network Graphics) to JPEG (Joint
Photographic Experts Group):
$ convert input.png -quality number output.jpeg
Uses lossless
compression
Uses lossy
compression
Quality measure of resulting
image. From 1 (worst quality,
greatest compression) to 100
(highest quality, lowest
compression)
C2110 UNIX and programming 13th Lesson -6-
Exercise
1. Copy test.png from file /home/kulhanek/Data/Komprese to your home directory.
2. What is size of image in bytes?
3. Do lossy compression of file to format jpeg. Use quality 10, 50 and 90. Save outputs
to under different names.
4. Compare quality visually (command display).
5. What is compression rate for quality 10 and 90?
C2110 UNIX and programming 13th Lesson -7Lossless
compression
Applications for lossless compression and decompression:
• gzip/gunzip
• bzip2/bunzip2
• zip/unzip
• and more ...
Text file compression:
$ gzip file.txt
$ bzip2 file.txt Output file wil be named file.txt.bz2
Output file will be named file.txt.gz
Compressed data decompression:
$ gunzip file.txt.gz
$ bunzip2 file.txt.bz2
Compression and decompression may be done in such a way, that result is written to
standard output (original file remains unchanged), for example:
$ bunzip2 --stdout file.txt.bz2 | wc
C2110 UNIX and programming 13th Lesson -8-
Exercise
1. Copy text file bu6_f.log from directory /home/kulhanek/Data/Komprese to your
home directory.
2. What is file size in bytes?
3. Do lossless compression of file using commands gzip and bzip2.
4. Which one has higher compression rate?
5. Which one does compression faster?
C2110 UNIX and programming 13th Lesson -9-
Archives
 Types
 Archives creation and extraction
C2110 UNIX and programming 13th Lesson -10Archives
- tar
In computing, tar (derived from tape archive) is both a file format (in the form of a type of
archive bitstream) and the name of a program used to handle such files. The format was
created in the early days of Unix and standardized by POSIX standard.
Initially developed to write data to tape backup devices, tar is now commonly used to
collect many files into one larger file for distribution or archiving, while preserving file
system information such as user and group permissions, dates, and directory structures.
www.wikipedia.org
Archive extraction:
$ tar xvf archive.tar
Archive creation:
$ tar cvf archive.tar directory/
$ cd directory
$ tar cvf /path/to/archive.tar *
If archive file name contains extension
.gz or .bz2 then archive is
automatically decompressed or
compressed.
C2110 UNIX and programming 13th Lesson -11-
Exercise
1. Find out meaning of option cvf of command tar?
2. Find out meaning of option xvf of command tar?
3. Create archive from files files saved in directory: /home/kulhanek/Data/Archive
4. What is size of archive file?
5. Do compression of archive. What is compress rate?
6. Extract archive to directory /scratch/your_login/archive
C2110 UNIX and programming 13th Lesson -12Source
code compilation
 Application Armagetron
 Archive extraction
 Configuration
 Compilation
 Installation
C2110 UNIX and programming 13th Lesson -13-
Armagetron
http://armagetronad.org/
Procedure:
1) Download source code
2) Extract archive
3) Read install instructions (README, INSTALL, doc/README, doc/INSTALL)
4) Configuration
5) Compilation
6) Installation
Holy Trinity
$ ./configure
$ make
$ make install
C2110 UNIX and programming 13th Lesson -14Armagetron,
procedure I
Do all steps in scratch.1) Extract archive:
$ tar xvf armagetronad-0.2.8.3.2.src.tar.gz
2) Create install directory, i.e. where will be programm installed (necessary if you are not root)
$ mkdir armagetronad
$ pwd
/scratch/kulhanek/game/armagetronad
3) Change current workdirectory to extracted archive data:
$ cd armagetronad-0.2.8.3.2
4) Configuration for compilation and installation:
$ ./configure --prefix=/scratch/kulhanek/game/armagetronad \
--disable-etc --disable-uninstall
In this stage, several libraries or applications maybe missing. These may be either installed by similar
approach, or more appropriate and faster is to ask administrator to install them. For compilation,
development versions of packages has to be installed.
E.g.: # apt-get install libxml2-dev
Path where will installation be saved.
C2110 UNIX and programming 13th Lesson -15Armagetron,
procedure II
5) Compilation
$ make
6) Instalation
$ make install
7) Running program
$ cd /scratch/kulhanek/game/armagetronad
$ bin/armagetronad
Path where program is installed.