C2110 UNIX and Programming 13th lesson -1C2110
UNIX and Programming
Petr Kulhánek
kulhanek@chemi.muni.cz
National Centre for Biomolecular Research, Faculty of Science,
Masaryk University, Kamenice 5, CZ-62500 Brno
13th lesson
C2110 UNIX and Programming 13th lesson -2-
Contents
➢ Data compression
• lossless vs. lossy compression
➢ Archives
• types of archives, creating and extracting archives
➢ Program compilation using source codes
• Archive extraction
• Configuration
• Compilation
• Installation
➢ New 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-
Compresion
Compression is a process which reduces size of the data (files).
This is achieved by searching redundant or irrelevant information in the data, which are
then stored more efficiently. Compression algorithms can be divided into two basic
categories:
• lossy compression – leads to irreversible loss of some irrelevant information, which is
usually tolerated, i.e., compressing video or audio data
• lossless compression – no loss of original information, compressed data can be fully
restored to their original state, the compression ratio is much lower than with lossy
compression
Restoring compressed data is called decompression.
Compress ratio is the measure of the compression quality. It is expressed as the ratio
between the size of the original and compressed data.
C2110 UNIX and Programming 13th lesson -5Lossy
compression
Programs for lossy compression and decompression:
• mplayer
• mencoder
• convert (Image Magick)
• and other...
Converting the image in PNG (Portable Network Graphics) format to JPEG (Joint
Photographic Experts Group):
$ convert input.png -quality number output.jpeg
uses lossless
compression
uses lossy
compresion
quality ratio of the final image
from 1 (worst quality with most
compression) to 100 (best quality
with worst compression)
C2110 UNIX and Programming 13th lesson -6-
Exercise
1. From the directory /home/kulhanek/Data/Komprese, copy the image test.png into
your home directory.
2. What is size of the image file in bytes?
3. Perform the lossy compression of the image to jpeg image. Use compression quality
10, 50 and 90. Store the resulting pictures separately.
4. Compare the visual quality of the compressed images (display command)
5. What is the compression ratio for the quality 10 and 90?
C2110 UNIX and Programming 13th lesson -7Lossless
compression
Programs for lossless compression and decompression:
• gzip/gunzip
• bzip2/bunzip2
• zip/unzip
• and other ...
Compression of a text file: :
$ gzip file.txt
$ bzip2 file.txt resulting file will be named
file.txt.bz2
resulting file will be named
file.txt.gz
Decompression of compressed data :
$ gunzip file.txt.gz
$ bunzip2 file.txt.bz2
Result of compression or decompression can be sent to the standard output (original file
then remains unchanged), e.g.:
$ bunzip2 --stdout file.txt.bz2 | wc
C2110 UNIX and Programming 13th lesson -8-
Exercise
1. From /home/kulhanek/Data/Komprese, copy the text file bu6_f.log to your home
directory.
2. What is the the size of the file in bytes?
3. Perform lossless compression of the file using programs gzip and bzip2. Which of
these two program has higher compress ratio?
4. Which of these two program compresses faster?
C2110 UNIX and Programming 13th lesson -9-
Archives
➢ types
➢ creating and extracting archives
C2110 UNIX and Programming 13th lesson -10Archives
- tar
tar (abbreviation from tape archiver) is a collective name for both the file format used to
store many different files and for single-purpose programs that work with this format. The
format itself was created at the beginning of Unix and later was standardized within the
POSIX standards. Originally it assisted with archiving files onto tape drives, but later its
usage expanded and today it is used, when appropriate for the purpose of distribution or
archiving, to join multiple files in one file, in a way that preserves information about the
directory structure, access rights and other attributes, which the file system normally
contains.
www.wikipedia.org
Archive extraction:
$ tar xvf archive.tar
Archive creation:
$ tar cvf archive.tar directory/
$ cd adresar
$ tar cvf /path/to/archive.tar *
if the name of the archive contains suffix
.gz or .bz2, archive is automatically
compressed or decompressed.
C2110 UNIX and Programming 13th lesson -11-
Exercise
1. What is meaning of the options cvf for command tar?
2. What is meaning of the options xvf for command tar?
3. Create archive from files stored in the directory: /home/kulhanek/Data/Archive
4. What is the size of archive file?
5. Perform compression of the archive. What is the compression ratio?
6. Extract archive into the directory /scratch/your_login/archive
C2110 UNIX and Programming 13th lesson -12Application
Compilation
➢ Application Armagetronad
➢ Extracting the archive
➢ Configuration
➢ Compilation
➢ Installation
C2110 UNIX and Programming 13th lesson -13-
Armagetronad
http://armagetronad.org/
Procedure:
1) Downloading of the source code
2) Extract the archive
3) Instruction for the installation (README, INSTALL, doc/README, doc/INSTALL)
4) Configuration
5) Compilation
6) Installation
Saint triple
$ ./configure
$ make
$ make install
C2110 UNIX and Programming 13th lesson -14Armagetronad,
Step I
All is performed in scratch.
1) Archive extraction:
$ tar xvf armagetronad-0.2.8.3.2.src.tar.gz
2) Making of installation directory, i.e., where the program will be installed (necessary if you
are not root)
$ mkdir armagetronad
$ pwd
/scratch/kulhanek/game/armagetronad
3) Change of working directory to extracted archive:
$ 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 phase, some libraries or application might be missing. They can be installed in the same way,
but it is more appropriate (and faster) to ask admin to install them. To compile, development
packages of individual libraries must be installed.
e.g.: # apt-get install libxml2-dev
where the program will be installed
C2110 UNIX and Programming 13th lesson -15Armagetronad,
Step II
5) Compilation
$ make
6) Installation
$ make install
7) Starting of the program
$ cd /scratch/kulhanek/game/armagetronad
$ ./bin/armagetronad
where the program is installed