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

2. Linux+ Guide to Linux Certification, 2e
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
Linux+ Guide to Linux Certification, 2e

3. 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
Linux+ Guide to Linux Certification, 2e

4. Linux+ Guide to Linux Certification, 2e
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
Linux+ Guide to Linux Certification, 2e

5. Linux+ Guide to Linux Certification, 2e
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
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6. The compress Utility (continued)
Table 12-1: Common options used with the compress utility
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7. Linux+ Guide to Linux Certification, 2e
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
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8. The gzip Utility (continued)
Table 12-2: Common options used with the gzip utility
Linux+ Guide to Linux Certification, 2e

9. The gzip Utility (continued)
Table 12-2 (continued): Common options used with the gzip utility
Linux+ Guide to Linux Certification, 2e

10. The gzip Utility (continued)
Table 12-2 (continued): Common options used with the gzip utility
Linux+ Guide to Linux Certification, 2e

11. Linux+ Guide to Linux Certification, 2e
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
Linux+ Guide to Linux Certification, 2e

12. The bzip2 Utility (continued)
Table 12-3: Common options used with the bzip2 utility
Linux+ Guide to Linux Certification, 2e

13. The bzip2 Utility (continued)
Table 12-3 (continued): Common options used with the bzip2 utility
Linux+ Guide to Linux Certification, 2e

14. Linux+ Guide to Linux Certification, 2e
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
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15. System Backup (continued)
Table 12-4: Common tape device files
Linux+ Guide to Linux Certification, 2e

16. Linux+ Guide to Linux Certification, 2e
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
Linux+ Guide to Linux Certification, 2e

17. The tar Utility (continued)
Table 12-5: Common options used with the tar utility
Linux+ Guide to Linux Certification, 2e

18. The tar Utility (continued)
Table 12-5 (continued): Common options used with the tar utility
Linux+ Guide to Linux Certification, 2e

19. The tar Utility (continued)
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
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20. Linux+ Guide to Linux Certification, 2e
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
Linux+ Guide to Linux Certification, 2e

21. The cpio Utility (continued)
Table 12-6: Common options used with the cpio utility
Linux+ Guide to Linux Certification, 2e

22. The cpio Utility (continued)
Table 12-6 (continued): Common options used with the cpio utility
Linux+ Guide to Linux Certification, 2e

23. 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
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24. 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
Linux+ Guide to Linux Certification, 2e

25. The dump/restore Utility (continued)
Figure 12-1: A sample backup strategy
Linux+ Guide to Linux Certification, 2e

26. The dump/restore Utility (continued)
Table 12-7: Common options used with the dump/restore utility
Linux+ Guide to Linux Certification, 2e

27. Linux+ Guide to Linux Certification, 2e
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
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28. Burning Software (continued)
Figure 12-2: The X-CD-Roast program
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29. 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
Linux+ Guide to Linux Certification, 2e

30. 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
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31. Compiling Source Code into Programs (continued)
Figure 12-3: The rdesktop program
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32. 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
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33. Installing Programs Using RPM (continued)
Figure 12-4: The bluefish program
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34. Installing Programs Using RPM (continued)
Table 12-8: Common options used with the rpm utility
Linux+ Guide to Linux Certification, 2e

35. Installing Programs Using RPM (continued)
Table 12-8 (continued): Common options used with the rpm utility
Linux+ Guide to Linux Certification, 2e

36. Installing Programs Using RPM (continued)
Figure 12-5: Configuring Fedora core software packages after installation
Linux+ Guide to Linux Certification, 2e

37. Linux+ Guide to Linux Certification, 2e
Summary
Many compression utilities are available for Linux systems; each uses a different compression algorithm and produces a different compression ratio
Files can be backed up to an archive using a backup utility
Tape devices are the most common medium used for archives
To back up files to CD-RW or DVD-RW, use burning software instead of a backup utility
Linux+ Guide to Linux Certification, 2e

38. Linux+ Guide to Linux Certification, 2e
Summary (continued)
tar is the most common backup utility used today
Creates compressed archives called tarballs
Source code for Linux software can be obtained and compiled afterward using the GNU C Compiler
Most source code is available in tarball format via the Internet
Linux+ Guide to Linux Certification, 2e

39. Linux+ Guide to Linux Certification, 2e
Summary (continued)
Package Managers install and manage compiled software of the same format
The Red Hat Package Manager is the most common package manager available for Linux systems today
Linux+ Guide to Linux Certification, 2e