Linux+ Unit 14

Course ILT

Compression, back-up, and software installation

Unit objectives  Use compression utilities to compress and decompress files  Perform system back-ups and view and extract archives  Compile and install software packages from source code and use the Red Hat Package Manager  Compress binary files and image files

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Topic A    

Topic A: Compression Topic B: System back-up Topic C: Software installation Topic D: Compressing binary and image files

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Compression  Process in which files are reduced in size by a compression algorithm  Compression algorithm – Instructions used to reduce the contents of a file

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Common compression utilities  compress  gzip  bzip2

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The compress utility  Uses an algorithm to make file smaller  Average ratio: 40-50%  zcat – Used to view the contents of archive created with compress or gzip

 zmore – Used to view page-by-page

 uncompress – Decompresses files that were processed with compress

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Common options with the compress utility

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GNU zip (gzip)  Algorithm varies slightly from that used by compress  Yields better compression  Typical ratio: 60-70%

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Common options with gzip

continued

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Common options with gzip, continued

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The bzip2 utility  Uses a different algorithm than compress or gzip  zcat and zmore cannot be used  Average ratio: 50-75%  bzcat – Used to view the contents of archive created with bzip2

 bunzip2 – Used to decompress files

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Common options with bzip2

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Activity A-1

Compressing and uncompressing files

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Topic B    

Topic A: Compression Topic B: System back-up Topic C: Software installation Topic D: Compressing binary and image files

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System back-up  Process of copying files to an archive  Archive – Location (file or device) that contains a copy of files – Typically created by a back-up utility

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Device files for different tape devices

magnetic tape (mt) command Course ILT

 Used to control tape devices

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Activity B-1

Discussing back-up media

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Back-up utilities  tar  cpio  dump/restore

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Tape archive (tar)  One of the oldest and most common back-up utilities  Accepts options to determine the location of the archive and the action to perform on the archive

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Common options with tar

continued

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Common options with tar, continued

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Tarballs  A gzip-compressed tar archive  Used for software distribution as well and back-up

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Activity B-2

Using the tar utility

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The copy in/out (cpio) utility  Common back-up utility  Options similar to tar with added features – Can back up device files and long filenames

 Uses absolute pathnames by default

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Common options with cpio

The dump/restore utility Course ILT

 Full back-up – Archives an entire filesystem

 Incremental back-up – Archives only files modified since the last full back-up

 Works only with files on ext2 and ext3 filesystems

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A sample back-up strategy

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Options with dump/restore

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restore command  Extracts archives created with the dump command

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Activity B-3

Using cpio and dump utilities

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Topic C    

Topic A: Compression Topic B: System back-up Topic C: Software installation Topic D: Compressing binary and image files

Forms of software distribution Course ILT

 Binary program files – Pre-compiled to run on specific hardware

 Source code – Must be compiled on the local architecture

 RPM package – Use Red Hat Package Management system

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Package manager  Defines a standard package format  Can be used to install, query, and remove packages  Red Hat Package Manager (RPM) – The most commonly used

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Compiling source code into programs

 The procedure for compiling source code into binary programs is standardized today among most open source software developers  GNU C Compiler (gcc) – Command used to compile source code into binary programs

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Activity C-1

Discussing forms of software distribution

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Installing from source code 1. 2. 3. 4.

Uncompress and extract files Run configure Run make Run make install

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The LTRIS program

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Activity C-2

Compiling and installing a program from source code

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RPMs  Filenames indicate hardware architecture the software was compiled for  rpm command – Command used to install, query, and remove RPM packages

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Common options with RPM

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Red Hat Package Manager  Graphical tool that may be used to install RPM packages available with the GNOME/KDE desktop environment

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The RPM interface

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Activity C-3

Using RPM to install and remove software

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Topic D    

Topic A: Compression Topic B: System back-up Topic C: Software installation Topic D: Compressing binary and image files

gzexe Course ILT

 Compresses binary programs

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Activity D-1

Using the gzexe utility

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Compressing images  Use the cjpeg program to compress .tga image files and convert them to JPEG format  The cjpeg program converts a .jpeg image file to grayscale

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Activity C-2

Using the cjpeg utility

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Unit summary  Compressed and decompressed files using compression utilities  Performed system back-ups and viewed and extracted archives  Compiled and installed software from source code, and use the Red Hat Package Manager  Compressed binary and image files