LPI Linux Certification in a Nutshell Part 23

fsck filesystems filesystems Check filesystems filesystems for errors and optionally correct them. for errors and optionally correct them.

dumpe2fs filesystem filesystem Display the detailed information about the ext2 ext2 or or ext3 ext3 filesystem at filesystem at filesystem filesystem.

tune2fs filesystem filesystem Modify filesystem variables for the ext2 ext2 or or ext3 ext3 filesystem at filesystem at filesystem filesystem.

Objective 104.3: Control Filesystem Mounting and Unmounting Managing the filesystem table /etc/fstab contains mount information for filesystems. Each line contains a single filesystem entry made up of six fields, shown in contains mount information for filesystems. Each line contains a single filesystem entry made up of six fields, shown in Table10-11 Table10-11.

The /media /media directory is often used by distributions as a place to automount hotplug devices, such as USB drives. directory is often used by distributions as a place to automount hotplug devices, such as USB drives.

Table10-11.Fields found in the /etc/fstab file

Entry Description Device The device file for the part.i.tion holding the filesystem.

Mount point The directory upon which the filesystem is to be mounted.

Filesystem type A filesystem type, such as ext3.

Mount options A comma-separated list.

Dump frequency For use with dump.

Pa.s.s number for fsck Used at boot time.

Mounting and unmounting The following commands are used to mount and unmount filesystems: mount device device mount directory directory mount device directory device directory Mount filesystems onto the hierarchy. The first and second forms consult /etc/fstab for additional information.

umount device device umount directory directory Unmount the filesystem on device device or mount it on or mount it on directory directory.

Filesystem types Common filesystem types compatible with Linux include: ext2 The standard Linux filesystem.

ext3 A journaling filesystem that is backward-compatible with ext2 ext2.

iso9660 The standard CD-ROM format.

vfat The Microsoft Windows FAT filesystem.

nfs Remote servers.

proc A system abstraction for access to kernel parameters.

swap Swap part.i.tions.

Objective 104.4: Set and View Disk Quotas Quota types Per-user hard The maximum size for an individual.

Per-user soft A warning threshold.

Per-group hard The maximum size for a group.

Per-group soft A warning threshold.

Grace period A time restriction on the soft limit.

Commands quota user user quota -g group group Display quota limits on user user or or group group.

quotaon [filesystems]

Enable previously configured disk quotas on one or more filesystems filesystems.

quotaoff [filesystems]

Disable disk quotas on one or more filesystems filesystems.

quotacheck [filesystems]

Examine filesystems and compile quota databases. Usually run via cron cron.

edquota names names Modify user or group quotas by sp.a.w.ning a text editor.

repquota filesystems filesystems Display a summary report of quota status for filesystems filesystems, or use -a -a for all filesystems. for all filesystems.NoteEnabling quotas requires usrquota usrquota and/or and/or grpquota grpquota options in options in /etc/fstab /etc/fstab, creation of quota.user quota.user and and quota.group quota.group files at the top of the filesystem, a files at the top of the filesystem, a quotacheck quotacheck, and a quotaon quotaon.

Objective 104.5: Manage File Permissions and Owners.h.i.+p Access control Access control is implemented using a set of properties called the access mode access mode, stored in the inode. Three cla.s.ses of user are defined:UserThe user who owns the file.GroupThe group that owns the file.OtherAll other users on the system.

Three permissions are either granted or not granted to each cla.s.s of user:Read (r)Allows access to file contents and listing of directory contents.Write (w)Allows writing a file or creating files in a directory.Execute (x)Allows execution of a file and ability to read/write files in a directory.

These comprise nine bits in the mode User rwx rwx, Group rwx rwx, and Other rwx rwx.

Three additional mode bits are defined:SUIDTo grant processes the rights of an executable file's owner.SGIDTo grant processes the rights of an executable file's group.Sticky bitProhibits file deletion by nonowners.

These 12-mode bits are often referred to in octal notation as well as with mnemonic constructs.

Mode bits are displayed using such commands as ls ls and and stat stat.

Setting access modes New files receive initial access mode as described by the umask umask.

The umask umask strips specified bits from the initial mode settings. Typical umasks are 002 and 022. strips specified bits from the initial mode settings. Typical umasks are 002 and 022.

Existing file modes are changed using chmod chmod with either symbolic or octal mode specifications: with either symbolic or octal mode specifications: Symbolic:[ugoa][-+=][rwxXst]

Octal bits:userr,w,x,groupr,w,x,otherr,w,x rwxrwxrwx=111111111=777 rwxr-xr--=111101100=751 chmod uses the following syntax: uses the following syntax: chmod mode files mode files Modify the access mode on files files using a symbolic or octal using a symbolic or octal mode mode.

Commands for file owners.h.i.+p chown user-owner user-owner.group-owner files Change the owner and/or group of files files to to user-owner user-owner and/or and/or group-owner group-owner.

chgrp group-owner files group-owner files Change the group owners.h.i.+p of files files to to group-owner group-owner.chgrp functionality is included in functionality is included in chown chown.

Objective 104.6: Create and Change Hard and Symbolic Links Concepts A link is a pseudonym for another file.

Links take up very little s.p.a.ce in the filesystem.

A symbolic link symbolic link is a tiny file that contains a pointer to another file. Symbolic links can span filesystems. is a tiny file that contains a pointer to another file. Symbolic links can span filesystems.

A hard link hard link is a copy of a file's directory entry. Both directory entries point to the same inode and thus the same data, owners.h.i.+p, and permissions. is a copy of a file's directory entry. Both directory entries point to the same inode and thus the same data, owners.h.i.+p, and permissions.

ln ln has the following syntax: has the following syntax: ln file link file link ln files directory files directory Create link link to to file file or in or in directory directory for all for all files files. Symbolic links are created with the -s -s option. option.

Objective 104.7: Find System Files and Place Files in the Correct Location File Hierarchy Standard (FHS) The FHS is used by Linux distributions to standardize filesystem layout. It defines two categories of data use, each with opposing subtypes:Data sharingSharable data can be used by multiple host systems on a network. Nonsharable data is unique to one particular host system.Data modificationVariable data is changed continually by naturally occurring (i.e., frequent) processes. Static data is left alone, remaining unchanged over extended periods of time.

The FHS seeks to define the filesystem contents in these terms and locate information accordingly.

The directory hierarchy The root filesystem (/): Must contain utilities and files sufficient to boot the operating system, including the ability to mount other filesystems.

Should contain the utilities needed by the system administrator to repair or restore a damaged system.

Should be relatively small.

/usr contains system utilities and programs that do not appear in the contains system utilities and programs that do not appear in the / / (root) filesystem. It includes directories such as (root) filesystem. It includes directories such as bin bin, lib lib, local local, and src src.

/var contains varying data such as printer spools and logfiles, including directories such as contains varying data such as printer spools and logfiles, including directories such as log log, mail mail, and spool spool.

Locating files Various methods can be used to locate files in the filesystem:which command commandDetermine the location of command command and display the full pathname of the executable program that the sh.e.l.l would launch to execute it. and display the full pathname of the executable program that the sh.e.l.l would launch to execute it.find paths expression paths expressionSearch for files that match expression expression, starting at paths paths and continuing recursively. and continuing recursively.locate patterns patternsLocate files whose names match one or more patterns patterns by searching an index of files previously created. by searching an index of files previously created.updatedbRefresh (or create) the slocate slocate database, usually via database, usually via cron cron.whatis keywords keywordsapropos keywords keywordsSearch the whatis whatis database for database for keywords keywords. whatis whatis finds only exact matches, whereas finds only exact matches, whereas apropos apropos finds partial word matches. finds partial word matches.

Chapter11.Exam 102 Overview

LPI Exam 102 is the second of two exams required for the LPI's Level 1 certification (officially referred to as LPIC 1). This exam tests your knowledge on 6 of the 10 major Topic areas specified for LPIC Level 1. Each section details certain Objectives, which are described here and on the LPI website.

Each Topic contains a series of Objectives covering specific areas of expertise. Each of these Objectives is a.s.signed a numeric weight, which acts as an indicator of the importance of the Objective. Weights run between 1 and 8, with higher numbers indicating more importance. An Objective carrying a weight of 1 can be considered relatively unimportant and isn't likely to be covered in much depth on the exam. Objectives with larger weights are sure to be covered on the exam, so you should study these Topics closely. The weights of the Objectives are provided at the beginning of each Topic section.

Exam Topics are numbered using the topic.objective topic.objective notation (e.g., 101.1, 101.2, 102.1). The 100 series topics represent LPI Level 1 certification topics, which are unique to all levels of LPI exams (e.g., 101, 102, 201, 202, etc.). The objective number represents the objectives that are a.s.sociated with the Topic area (e.g., 1, 2, 3, 4, and so on). notation (e.g., 101.1, 101.2, 102.1). The 100 series topics represent LPI Level 1 certification topics, which are unique to all levels of LPI exams (e.g., 101, 102, 201, 202, etc.). The objective number represents the objectives that are a.s.sociated with the Topic area (e.g., 1, 2, 3, 4, and so on).

The Level 1 Topics are distributed between the two exams to create tests of similar length and difficulty without subject matter overlap. As a result, there's no requirement or advantage to taking the exams in sequence, the only caveat being that you cannot be awarded an LPIC 2 or higher certifications until you pa.s.s the requirements for the lower level certification.

The Topics for Exam 102 are listed in Table11-1 Table11-1.

Table11-1.LPI Topics for Exam 102

Name Number of objectives Description Sh.e.l.ls, Scripting, and Data Management 3 Covers the sh.e.l.l and its startup files and writing bash scripts, querying databases, and manipulating data using basic SQL commands. scripts, querying databases, and manipulating data using basic SQL commands.

User Interfaces and Desktops 3 The X-based Objectives cover only subjects that every Level 1 sysadmin is expected to encounter. Some of these tasks include installing and configuring X11, setting up a display manager such as XDM, GDM, or KDM, and installing and understanding basic accessibility tools.

Administrative Tasks 3 Covers all of the basic administrative tasks done by a junior level Linux sysadmin, including managing users and groups, user environment variables, job scheduling, and data backup.

Essential System Services 4 Covers administering system services that must be configured, including maintaining system time, system logs, basic understanding of mail transfer agents, and managing printing.

Networking Fundamentals 3 Explores TCP/IP, network interfaces, DHCP, and client-side DNS; includes troubleshooting commands.

Security 3 Covers security issues such as SUID issues, ssh client use, GPG for data encryption, and user limits. client use, GPG for data encryption, and user limits.

Exam 102 lasts a maximum of 90 minutes and contains exactly 60 questions. The exam is administered using a custom application on a PC in a private room with no notes or other reference material. The majority of the exam is made up of multiple-choice single-answer questions. These questions have only one correct answer and are answered using radio b.u.t.tons. A few of the questions present a scenario needing administrative action. Others seek the appropriate commands for performing a particular task or for proof of understanding of a particular concept. Some people may get an exam with an additional 20 items. These items are used to test new questions and don't count as part of the score. An additional 30 minutes is provided in this case, and there is no indication of which items are unscored.

The exam also includes a few multiple-choice multiple-answer questions, which are answered using checkboxes. These questions can have multiple correct responses, each of which must be checked. These are probably the most difficult type of question to answer because the possibility of multiple answers increases the likelihood of mistakes. An incorrect response on any one of the possible answers causes you to miss the entire question.

The exam also has some fill-in-the-blank questions. These questions provide a one-line text area input box for you to fill in your answer. These questions check your knowledge of concepts such as important files, commands, or well-known facts that you are expected to know.

Chapter12.Exam 102 Study Guide

The second part of this book contains a section for each of the six Topics found on Exam 102 for LPIC Level 1 certification. Each of the following tables details the Objectives described for the corresponding Topic on the LPI website.

Exam Preparation LPI Exam 102 is thorough, but if you have a solid foundation in Linux concepts as described here, you should find it straightforward. If you've already taken Exam 101, you'll find that Exam 102 covers a broader range of Linux administration skills. Included are user interfaces, printing, doc.u.mentation, sh.e.l.ls and scripting, administrative tasks, networking fundamentals, system services, and security. Exam 102 is quite specific on some Topics, such as network applications (for example, Sendmail), but you won't come across questions intended to trick you, and you're unlikely to find questions that you feel are ambiguous.

For clarity, this material is presented in the same order as the LPI Topics and Objectives. To a.s.sist you with your preparation, Table12-1 Table12-1 through 12-9 provide a complete listing of the Topics and Objectives for Exam 102. Because of changes made during test development, the final Objectives are not always in exact numerical order. After you complete your study of each Objective, simply check it off here to measure and organize your progress. through 12-9 provide a complete listing of the Topics and Objectives for Exam 102. Because of changes made during test development, the final Objectives are not always in exact numerical order. After you complete your study of each Objective, simply check it off here to measure and organize your progress.

Table12-1.Sh.e.l.ls, Scripting, and Data Management (Topic 105)

Objective Weight Description 1 4 Customize and Use the Sh.e.l.l Environment 2 4 Customize or Write Simple Scripts 3 2 SQL Data Management

Table12-2.The X Window System (Topic 106)