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Linux+ Guide to Linux Certification, Third Edition

Chapter 11 Compression, System Backup, and Software Installation. Linux+ Guide to Linux Certification, Third Edition. Objectives. Outline the features of common compression utilities Compress and decompress files using common compression utilities

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Linux+ Guide to Linux Certification, Third Edition

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  1. Chapter 11 Compression, System Backup, and Software Installation Linux+ Guide to Linux Certification, Third Edition

  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, 3e

  3. Objectives (continued) • Use burning software to back up files to CD and DVD • 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 • Use the yum command to obtain software from Internet software repositories Linux+ Guide to Linux Certification, 3e

  4. Compression • Compression: process in which files are reduced in size by stripping out characters • Compression algorithm: standard set of instructions used to compress a file • Compression ratio: percentage by which the file size was decreased • Common compression utilities include compress, gzip, and bzip2 Linux+ Guide to Linux Certification, 3e

  5. The compress Utility • Use to compress files using the Adaptive Lempel Ziv coding (LZW) compression algorithm • Average compression ratio of 40-50% • compress command: used to compress files • zcat command: used to display the contents of an archive created with compress • Can use zmore and zless commands to view contents page-by-page • uncompress command: used to decompress files compressed by compress command Linux+ Guide to Linux Certification, 3e

  6. The compress Utility (continued) Table 11-1: Common options used with the compress utility Linux+ Guide to Linux Certification, 3e

  7. The gzip Utility • GNU zip (gzip): used to compress files using the Lempel-Ziv compression algorithm (LZ77) • Varies slightly from algorithm used by compress • Average compression ratio of 60-70% • Uses .gz filename extension by default • Can control level of compression via numeric option • gunzip command: used to decompress .gz files Linux+ Guide to Linux Certification, 3e

  8. The gzip Utility (continued) Table 11-2: Common options used with the gzip utility Linux+ Guide to Linux Certification, 3e

  9. The gzip Utility (continued) Table 11-2 (continued): Common options used with the gzip utility Linux+ Guide to Linux Certification, 3e

  10. The gzip Utility (continued) Table 11-2 (continued): Common options used with the gzip utility Linux+ Guide to Linux Certification, 3e

  11. The bzip2Utility • 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 • Uses .bz2 filename extension by default • bunzip2 command: used to decompress files compressed via bzip2 Linux+ Guide to Linux Certification, 3e

  12. The bzip2Utility (continued) Table 11-3: Common options used with the bzip2 utility Linux+ Guide to Linux Certification, 3e

  13. The bzip2Utility (continued) Table 11-3 (continued): Common options used with the bzip2 utility Linux+ Guide to Linux Certification, 3e

  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, 3e

  15. System Backup (continued) Table 11-4: Common tape device files Linux+ Guide to Linux Certification, 3e

  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 • tar command: activates tar utility • Arguments list the files to place in the archive • Accepts options to determine location of archive and action to perform on archive Linux+ Guide to Linux Certification, 3e

  17. The tar Utility (continued) Table 11-5: Common options used with the tar utility Linux+ Guide to Linux Certification, 3e

  18. The tar Utility (continued) -x Extract Archive -c Create New Archive -r Append to Archive -v verbose -f Write/Read File -t List Archive Contents -z Compress using gzip (c mode only) Table 11-5 (continued): Common options used with the tar utility Linux+ Guide to Linux Certification, 3e

  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 • Use options of the tar command to compress an archive immediately after creation Linux+ Guide to Linux Certification, 3e

  20. The cpio Utility • Copy in/out (cpio): common backup utility • Activated by the cpio command • Has various options • 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, 3e

  21. The cpio Utility (continued) Table 11-6: Common options used with the cpio command Linux+ Guide to Linux Certification, 3e

  22. The cpio Utility (continued) -i Extract contents to disk -o output -p pass-through. Read list of files and copy to specified directory -Z Compress -z gzip -u Unconditional Write -d Create directories as necessary -O file Write archive to file -t read contents to standard out -y bzip2 Table 11-6 (continued): Common options used with the cpio command Linux+ Guide to Linux Certification, 3e

  23. The dump/restore Utility • dump/restore: Used to back up files and directories to device or file on filesystem • Works only with files on ext2 and ext3 filesystems • Designed to backup entire filesystems to an archive • /etc/dumpdates: file used to store information about incremental and full backups Linux+ Guide to Linux Certification, 3e

  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 • Can perform up to nine different incremental backups • dump command: create archives for full or incremental backup • restore command: extract archives created with dump Linux+ Guide to Linux Certification, 3e

  25. The dump/restore Utility (continued) Figure 11-1: A sample back-up strategy Linux+ Guide to Linux Certification, 3e

  26. The dump/restore Utility (continued) Table 11-7: Common options used with the dump/restore utility Linux+ Guide to Linux Certification, 3e

  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 • Disc burning software: used to write files to CD or DVD media • Build CD or DVD filesystem, organize the data, and write it all to CD or DVD • Fedora 13 comes with Brasero Disc Burner burning software Linux+ Guide to Linux Certification, 3e

  28. Burning Software (continued) Figure 11-2: The Brasero Disc Burner program Linux+ Guide to Linux Certification, 3e

  29. Software Installation • Software for Linux can consist of: • Binary files precompiled to run on certain hardware architectures • Source code, which must be compiled before use • 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, 3e

  30. Compiling Source Code into Programs • Procedure for compiling source code into binary programs standardized among most OSS developers • make command: looks for Makefile and it to compile the source code into binary using compiler • Makefile: contains most of the information and commands necessary to compile a program, as well as instructions for use of commented areas • make install command: copies complied executable programs to correct location Linux+ Guide to Linux Certification, 3e

  31. Compiling Source Code into Programs (continued) Figure 11-3: The rdesktop program Linux+ Guide to Linux Certification, 3e

  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, 3e

  33. Installing Programs Using RPM (continued) • After installation RPM database is updated to contain information about the installed package and files contained in it -q option: query the full package name -i option: together with –q used to display full package information -f option: together with –q used to display the package to which a specific file belongs -e option: used to remove a package from the system Linux+ Guide to Linux Certification, 3e

  34. Installing Programs Using RPM (continued) Figure 11-4: The bluefish program Linux+ Guide to Linux Certification, 3e

  35. Installing Programs Using RPM (continued) Table 11-8: Common options used with the rpm utility Linux+ Guide to Linux Certification, 3e

  36. Installing Programs Using RPM (continued) Table 11-8 (continued): Common options used with the rpm utility Linux+ Guide to Linux Certification, 3e

  37. Installing Programs Using RPM (continued) • Most RPM packages are located on Internet Servers • Called software repositories • yum command: used to search Internet software repositories for RPM packages • Installs dependent packages if necessary • yum install packagename command • yum update packagenamecommand • KPackageKit: graphical utility for installing or updating packages Linux+ Guide to Linux Certification, 3e

  38. Installing Programs Using RPM (continued) Figure 11-5: The KPackageKit utility Linux+ Guide to Linux Certification, 3e

  39. 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 • To back up files to CD-RW or DVD-RW, use burning software instead of a backup utility Linux+ Guide to Linux Certification, 3e

  40. Summary (continued) • tar is the most common backup utility used today • Typically used to create 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, 3e

  41. 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 • You can install or upgrade RPM packages using the yum command • yum command obtains RPM packages from software repositories on the Internet Linux+ Guide to Linux Certification, 3e

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