Linux+ Guide to Linux Certification Chapter 12 Compression, System Backup, and Software Installation.

Linux+ Guide to Linux Certification

Chapter 12Compression, System Backup,

and Software Installation

Linux+ Guide to Linux Certification, 2e 2

Objectives

• Outline the features of common compression utilities

• Compress and decompress files using common compression utilities

• Perform system backups using the tar, cpio, and dump commands

• View and extract archives using the tar, cpio, and restore commands


Objectives (continued)

• Use burning software to back up files to CD-RW and DVD-RW

• Describe common types of Linux software

• Compile and install software packages from source code

• Use the Red Hat Package Manager to install, manage, and remove software packages


Compression

• Compression: Process in which files are reduced in size by a compression algorithm

• Compression algorithm: Set of instructions used to systematically reduce a file’s contents

• Compression ratio: Amount of compression occurring during compression

• Three most common compression utilities:– Compress– gzip– bzip2


The compress Utility

• compress command: Used to compress files using Lempel-Ziv compression algorithm

• zcat command: Used to view contents of an archive created with compress or gzip to Standard Output

• uncompress command: Used to decompress files compressed by compress command


The compress Utility (continued)

Table 12-1: Common options used with the compress utility


The gzip Utility

• GNU zip (gzip): Used to compress files using Lempel-Ziv compression algorithm– Varies slightly from algorithm used by compress– Typically yields better compression than compress– Uses .gz filename extension by default– Can control level of compression

• gunzip command: Used to decompress .gz files


The gzip Utility (continued)

Table 12-2: Common options used with the gzip utility



Table 12-2 (continued): Common options used with the gzip utility



Table 12-2 (continued): Common options used with the gzip utility


The bzip2 Utility

• bzip2 command: Used to compress files using Burrows-Wheeler Block Sorting Huffman Coding compression algorithm– Cannot compress directory full of files– Cannot use zcat and zmore to view files

• Must use bzcat command

– Compression ratio is 50% to 75% on average

• bunzip2 command: Used to decompress files compressed via bzip2


The bzip2 Utility (continued)

Table 12-3: Common options used with the bzip2 utility


The bzip2 Utility (continued)

Table 12-3 (continued): Common options used with the bzip2 utility


System Backup

• System backup: Process whereby files are copied to an archive

• Archive: Location (file or device) that contains copy of files– Typically created by a backup utility

• Should backup user files from home directories and any important system configuration files– Possibly files used by system services, as well

• Several backup utilities available– tar, cpio, dump/restore, burning software


System Backup (continued)

Table 12-4: Common tape device files


The tar Utility

• Tape archive (tar) utility: One of oldest and most common backup utilities– Can create archive in a file on a filesystem or directly

on a device– Accepts options to determine location of archive and

action to perform on archive


The tar Utility (continued)

Table 12-5: Common options used with the tar utility



Table 12-5 (continued): Common options used with the tar utility



• tar utility does not compress files inside archive– Time needed to transfer archive across a network is

high– Can compress archive

• Backing up files to compressed archive on a filesystem is useful when transferring data across a network– Ill suited to backing up large amounts of data for

system recovery


The cpio Utility

• Copy in/out (cpio): Common backup utility– Includes options similar to tar utility– Has added features

• Ability to back up device files

• Long filenames

– Uses absolute pathnames by default when archiving


The cpio Utility (continued)

Table 12-6: Common options used with the cpio utility


The cpio Utility (continued)

Table 12-6 (continued): Common options used with the cpio utility


The dump/restore Utility

• dump/restore: Used to back up files and directories to device or file on filesystem– Works with files on ext2 and ext3 filesystems

• /etc/dumpdates: File used to store information about incremental and full backups


The dump/restore Utility (continued)

• Full backup: Archiving all data on filesystem

• Incremental backup: Backs up only data that has changed since last backup

• restore command: Extract archives created with dump



Figure 12-1: A sample backup strategy



Table 12-7: Common options used with the dump/restore utility


Burning Software

• tar, cpio, and dump utilities copy data to backup medium in character-by-character or block-by-block format– Typically used with tape, floppy, and hard disk media

• Burning software: Used to write files to CD-RW or DVD-RW media

• Red Hat Fedora Core 2 comes with X-CD-Roast


Burning Software (continued)

Figure 12-2: The X-CD-Roast program


Software Installation

• Software for Linux can consist of: – Binary files precompiled to run on certain hardware

architectures – Source code, which must be compiled

• Typically distributed in tarball format

• Package manager: System that defines standard package format – Used to install, query, and remove packages

• Red Hat Package Manager (RPM): Most common package manager used by Linux systems today


Compiling Source Code into Programs

• Procedure for compiling source code into binary programs standardized among most OSS developers

• GNU C Compiler (gcc): Command used to compile source code into binary programs– After compilation, must move program files to

appropriate directory

• Makefile: Contains most of information and commands necessary to compile program


Compiling Source Code into Programs (continued)

Figure 12-3: The rdesktop program


Installing Programs Using RPM

• Packages in RPM format have filenames that indicate hardware architecture for which the software was compiled– End with .rpm extension

• To install an RPM package, use –i option to rpm command– Command used to install, query, and remove RPM

packages


Installing Programs Using RPM (continued)

Figure 12-4: The bluefish program



Table 12-8: Common options used with the rpm utility



Table 12-8 (continued): Common options used with the rpm utility



Figure 12-5: Configuring Fedora core software packages after installation

Linux+ Guide to Linux Certification Chapter 12 Compression, System Backup, and Software Installation.

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