Linux+ Guide to Linux Certification Chapter One Introduction to Linux.
Linux+ Guide to Linux Certification
description
Transcript of Linux+ Guide to Linux Certification
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
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
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
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
Linux+ Guide to Linux Certification, 2e 6
The compress Utility (continued)
Table 12-1: Common options used with the compress utility
Linux+ Guide to Linux Certification, 2e 7
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
Linux+ Guide to Linux Certification, 2e 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
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
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
Linux+ Guide to Linux Certification, 2e 15
System Backup (continued)
Table 12-4: Common tape device files
Linux+ Guide to Linux Certification, 2e 16
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
Linux+ Guide to Linux Certification, 2e 20
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
Linux+ Guide to Linux Certification, 2e 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
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
Linux+ Guide to Linux Certification, 2e 28
Burning Software (continued)
Figure 12-2: The X-CD-Roast program
Linux+ Guide to Linux Certification, 2e 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
Linux+ Guide to Linux Certification, 2e 31
Compiling Source Code into Programs (continued)
Figure 12-3: The rdesktop program
Linux+ Guide to Linux Certification, 2e 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
Linux+ Guide to Linux Certification, 2e 33
Installing Programs Using RPM (continued)
Figure 12-4: The bluefish program
Linux+ Guide to Linux Certification, 2e 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