Linux+ Guide to Linux Certification Chapter Thirteen Compression, System Back-Up, and Software Installation

Objectives Outline the features of common compression utilities Compress and decompress files using common compression utilities Perform system back-ups using the tar, cpio, and dump commands View and extract archives using the tar, cpio, and restore commands

Objectives 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 instruction used to reduce the contents of a file systematically Compression ratio –Amount of compression that occurred during compression

Compression The three most common compression utilities available to Linux users: –compress –gzip –bzip2

The compress Utility compress command –Command used to compress files using a Lempel- Ziv compression algorithm zcat command –Command used to view the contents of an archive created with compress or gzip to Standard Output

The compress Utility zmore command –Command used to view the contents of an archive created with compress or gzip to Standard Output in a page-by-page fashion uncompress command –Command used to decompress files compressed by the compress command

The compress Utility Table 13-1: Common options used with the compress utility

The gzip Utility GNU zip (gzip) –Command used to compress files using a Lempel- Ziv compression algorithm Varies slightly from the algorithm used by the compress utility –Typically, this algorithm yields better compression than the one used by compress

The gzip Utility Table 13-2: Common options used with the gzip utility

The gzip Utility Table 13-2 (continued): Common options used with the gzip utility

The bzip2 Utility bzip2 command –Command used to compress files using a Burrows-Wheeler Block Sorting Huffman Coding compression algorithm –Cannot be used to compress a directory full of files –The zcat and zmore commands cannot be used to view files zipped with bzip2 –The compression ratio is 50-75% on average

The bzip2 Utility bzcat command –Command used to view the contents of an archive created with bzip2 to Standard Output bunzip2 command –Command used to decompress files compressed by the bzip2 command

The bzip2 Utility Table 13-3: Common options used with the bzip2 utility

The bzip2 Utility Table 13-3 (continued): Common options used with the bzip2 utility

System Back-Up System back-up –Process whereby files are copied to an archive Archive –The location (file or device) that contains a copy of files –It is typically created by a back-up utility

System Back-Up Table 13-4: Common tape device files

System Back-Up magnetic tape (mt) command –Command used to control tape devices The most common back-up utilities: –tar –cpio –dump/restore

The tar Utility Tape archive utility –One of the oldest and most common back-up utilities –Can create an archive in a file on a filesystem or directly on a device –Accepts options to determine the location of the archive and the action to perform on the archive

The tar Utility Table 13-5: Common options used with the tar utility

The tar Utility Table 13-5 (continued): Common options used with the tar utility

The tar Utility Table 13-5 (continued): Common options used with the tar utility

The tar Utility Tarballs –A gzip-compressed tar archive Backing up files to a compressed archive on a filesystem is useful when transferring data across a network but is ill-suited to backing up large amounts of data for system recovery

The cpio Utility Copy in/out (cpio) –Common back-up utility –Includes options similar to the tar utility, but has some added features including the ability to back up device files and long filenames –Uses absolute pathnames by default when archiving

The cpio Utility Table 13-6: Common options used with the cpio utility

The cpio Utility Table 13-6 (continued): Common options used with the cpio utility

The dump/restore Utility dump/restore –Can be used to back up files and directories to a device or to a file on the filesystem –Can only work with files on ext2 and ext3 filesystems /etc/dumpdates –File used to store information about incremental and full back-ups for use by the dump/restore utility

The dump/restore Utility Full back-up –An archive of an entire filesystem Incremental back-up –Archive of a filesystem that contains only files that were modified since the last archive was created

The dump/restore Utility Figure 13-1: A sample back-up strategy

The dump/restore Utility Table 13-7: Common options used with the dump/restore utility

The dump/restore Utility restore command –Command used to extract archives created with the dump command Table 13-7 (continued): Common options used with the dump/restore utility

Software Installation Package manager –System that defines a standard package format and can be used to install, query, and remove packages Red Hat Package Manager (RPM) –The most commonly used package manager for Linux

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

Compiling Source Code into Programs Figure 13-2: The LTRIS program

Installing Programs Using RPM Packages in the RPM format have filenames that indicate the hardware architecture the software was compiled for, and end with the.rpm extension rpm command –Command used to install, query, and remove RPM packages

Installing Programs Using RPM Figure 13-3: The bluefish program

Installing Programs Using RPM Table 13-8: Common options used with the rpm utility

Installing Programs Using RPM Table 13-8 (continued): Common options used with the rpm utility

Installing Programs Using RPM GNOME RPM Manager –Graphical tool that may be used to install RPM packages available with the GNOME desktop environment KDE Package Manager –Graphical tool that may be used to install RPM packages available with the KDE desktop environment

Installing Programs Using RPM Figure 13-4: The GNOME RPM Manager

Installing Programs Using RPM Figure 13-5: The KDE Package Manager

Chapter Summary There are many compression utilities available for Linux systems Files may be backed up to an archive using a back-up utility The tar utility is the most common back-up utility used today

Chapter Summary The source code for Linux software may be obtained and compiled afterwards using the GNU C Compiler Package managers install and manage compiled software of the same format The Red Hat Package Manager can be used to install software in Red Hat Package Manager format