Red Hat Certified engineer course

Red Hat Certified engineer course Ali Abdo “ Linatrix”

AGENDA Course roles Participant Introductions What is RHCT, RHCE & why ? Course sequence and overview First level

Course roles time, participate,mobile,selected,feedback

Participant Introductions instructor Please introduce yourself :- -name. -job. -computer background. -”why you are here” ? -what you will do with this course?

RH033: Red Hat Linux Essentials “First level”

Course Description The first course for both RHCT and RHCE certification tracks, RH033 is for who have never used Linux or UNIX, and who have no prior command line experience in any other operating system. You are taught the basics of a Red Hat Enterprise Linux environment, and it prepares you for your future role as a system administrator.

Prerequisites User-level experience with any computer system, use of menus, use of any graphical user interface. Goal A Red Hat Enterprise Linux power user who can be productive in using and customizing a Red-Hat system for common command line processes and desktop productivity roles. Audience Users who are new to Linux and have no prior UNIX or command line skills, who want to develop and practice the basic skills to use and control their own Red Hat Linux system.

Course Objectives 1. Understand the Linux file system 2. Perform common file maintenance 3. Use and customize the GNOME interface 4. Issue essential Linux commands from the command line 5. Perform common tasks using the GNOME GUI 6. Open, edit, and save text documents using the vi editor 7. File access permissions 8. Customize X Window System 9. Regular expression pattern matching and I/O redirection 10. Install, upgrade, delete and query packages on your system 11. Network utilities for the user 12. Power user utilities

RH133: Red Hat Linux System Administration Red Hat Certified Technician (RHCT) “second level”

Course Description RH133 focuses on skills in systems administration on Red Hat Linux, to a level where you can attach and configure a workstation on an existing network. This course provides intensive hands-on training on Red Hat Enterprise Linux, and it prepare for the RHCT Certification .

Prerequisites RH033 Red Hat Linux Essentials or equivalent experience with Red Hat Linux. Goal Upon successful completion of this course, students will possess basic Linux system administrator knowledge which can be proved by passing the RHCT Exam. The exam is a performance based lab exam that tests actual ability to install, configure, and attach a new Red Hat Linux system to an existing production network. Audience Linux or UNIX users who understand the basics of Red Hat Linux and desire further technical training to begin the process of becoming a system administrator.

Course Objectives 1. Install Red Hat Linux interactively and with Kickstart 2. Control common system hardware; administer Linux printing subsystem 3. Create and maintain the Linux file system 4. Perform user and group administration 5. Integrate a workstation with an existing network 6. Configure a workstation as a client to NIS, DNS, and DHCP services 7. Automate tasks with at, cron, and anacron 8. Back up file systems to tape and tar archive 9. Manipulate software packages with RPM 10. Configure the X Window System and the GNOME d.e. 11. Perform performance, memory, and process mgmt. 12. Configure basic host security

RH253 Red Hat Linux Networking and Security Administration Red Hat Certified engineer(RHCE) “third level”

Course Description RH253 arms students with in-depth knowledge needed to configure common Red Hat Enterprise Linux network services. Network and local security tasks are also topics of this course.

Prerequisites RH133 Red Hat Linux System Administration or equivalent experience with Red Hat Enterprise Linux, LAN/WAN fundamentals or equivalent, internet working with TCP/IP or equivalent. Goal Upon completion of this course, individuals can set up a Red Hat Enterprise Linux server and configure common network services and security at a basic level. Audience Linux or UNIX system administrators who already have some experience with Red-Hat Enterprise Linux systems administration, want course in networking services and security, and want to build skills at configuring network services and security administration .

Course Objectives 1. Networking services on Red Hat Linux server-side setup, configuration, and basic administration of common networking services: DNS, NIS, Apache, SMB, DHCP, Sendmail, FTP, proxy. 2. Introduction to security 3. Developing a security policy 4. Local security 5. Files and file system security 6. Password security 7. Kernel security 8. Basic elements of a firewall 9. Red Hat Linux-based security tools 10. Responding to a break-in attempt 11. Security sources and methods 12. Overview of security tools

Unit 1 Linux Ideas and History what is the open source history of open source what is Linux ? & history of Linux Linux Distributions Red hate Distributions Linux principles

Unit 2 Linux Usage Basics Logging in to a Linux System Switching between virtual consoles and the graphical environment Elements of the X Window System Starting the X server Changing Your Password The “root” user ... ? Changing Identities [su sudo] Editing text files [vim , nano, gedit, etc ]

Unit 3 Running Commands and Getting Help shell ... ? what is Command ? Running Commands Some essential Commands Getting Help [ man , info, --help ] Reading Usage Summaries The whatis , which , whereis Commands The man Command and man Pages The info Command and info Pages Extended Documentation

Unit 4 Browsing the File system Linux File Hierarchy Concepts Some Important Directories File and Directory Names Absolute and Relative Path names Changing Directories [cd] Listing Directory Contents [ls] Copying Files and Directories [cp] Moving and Renaming Files and Directories [mv] Creating and Removing Files Creating and Removing Directories Using Nautilus [Moving , Copying ,Moving and Copying] Determining File Content [file]

Unit 5 Users, Groups and Permissions Users Groups Linux File Security Permission Precedence Permission Types Examining Permissions Changing File Ownership Changing Permissions Symbolic, Numeric and Nautilus Symbolic link and hard link

Unit 6 Using the bash Shell Command Line Shortcuts File Gobbling, The Tab Key History , History Tricks Command Line Expansion,Commands and Braced Sets Command Editing Tricks gnome-terminal Scripting Basics Creating Shell Scripts Samples

Unit 7 Standard I/O and Pipes Standard Input and Output [ STDIN , STDOUT, STDERR] Redirecting Output to a File , Examples Redirecting STDOUT to a Program (Piping)‏ Combining Output and Errors Redirecting to Multiple Targets [tee] Redirecting STDIN from a File Sending Multiple Lines to STDIN Scripting: for loops , examples

Unit 8 Text Processing Tools Tools for Extracting Text Viewing File Contents Extracting Text by Keyword, Column Tools for Analyzing Text Gathering Text Statistics Sorting Text Eliminating Duplicate Lines Comparing Files Duplicating File Changes Spell Checking with aspell Tools for Manipulating Text Special Characters for Complex Searches

Unit 9 vim: An Advanced Text Editor Introducing vim vim: A Modal Editor vim Basics [Opening a file, Modifying a File, Saving a File and Exiting] Using Command Mode [Moving Around, Search and Replace , Manipulating Text, Undoing] Visual Mode Using multiple "windows" Configuring vi and vim

Unit 10 Basic System Configuration Tools TCP/IP Network Configuration Managing Ethernet Connections Graphical Network Configuration [system-config-network] Network Configuration Files [Ethernet Devices, Global Network Settings, DNS] Printing in Linux [system-config-printer, Commands] Setting the System's Date and Time [ system-config-date, date ]

Unit 11 Investigating and Managing Processes What is a Process? Listing Processes, Finding Processes Signals ,Sending Signals to Processes Scheduling Priority Altering Scheduling Priority Interactive Process Management Tools [ gnome-system-monitor, top ] Job Control Scheduling a Process To Execute Later [at , crontab] Grouping Commands , Exit Status Conditional Execution Operators The test Command Scripting: if Statements

Unit 12 Configuring the Bash Shell Bash Variables Environment Variables Some Common Variables Aliases How bash Expands a Command Line , Preventing Expansion Login vs non-login shells Bash start up tasks: profile Bash start up tasks: bashrc Bash exit tasks Scripting: Taking input with positional Parameters Scripting: Taking input with the read command

Unit 13 Finding and Processing Files locate find The Gnome Search Tool

Unit 14 Network Clients Web Clients Non-GUI Web Browsers wget Evolution Non-GUI Mail Clients Open Ssh: Secure Remote Shell , scp rsync: Efficient File Sync FTP Clients,smbclient File Transfer with Nautilus Network Diagnostic Tools [ ping , tracrout, host dig netstat, gnome-nettool]

Unit 15 Advanced Topics in Users, Groups and Permissions User and Group ID Numbers User management tools System Users and Groups Monitoring Logins Default Permissions Special Permissions for Executables Special Permissions for Directories

Unit 16 The Linux Filesystem In-Depth Partitions and Filesystems Inodes and Directories cp and inodes mv and inodes rm and inodes Hard Links ,Symbolic The Fundamental File types Checking Free Space Removable Media , Mounting Archiving Files and Compressing

Unit 17 Essential System Administration Tools Planning an Installation Performing an Installation Managing Services Managing Software The Yum Package Management Tool Graphical Package Management Securing the System SELinux Packet Filtering iptables Firewall and SELinux Configuration [ system-config-securitylevel

Unit 1 Linux Ideas and History what is the open source history of open source what is Linux ? history of Linux Linux Distributions Red hate Distributions Linux principles

Objectives Upon completion of this unit, you should be able to: Explain the nature of open source software Discuss the origins of Linux List the Linux operating system Distributions List the Red Hat operating system distributions Explain basic Linux principles

What is Open Source? Open source : software and source code available to all The freedom to distribute software and source code The ability to modify and create derived works

history of open source 1983 -1985 Stallman's FSF , GNU and GPL GNU stands for “GNU's Not Unix” Creates open source version of UNIX utilities Creates the General Public License (GPL)‏ Software license enforcing open source principles

what is GNU/Linux ? Linux is is a Unix-like [Unix clone]operating system that was designed to provide personal computer users a free or very low-cost operating system. Linux's kernel (the central part of the operating system) was developed by Linus Torvalds at the University of Helsinki in Finland. To complete the operating system, Torvalds and other team members made use of system components developed by members of the Free Software Foundation for the GNU Project.

why is GNU/Linux ? -Speed and Stability -Open Source tends to be high quality and economical. -Security: very little security holes & quick fixes. -True multiuser system (secure file permission )‏ -Modularity (User isn't locked to one shell or GUI). -Strong communities for development and support.

GNU/Linux Historical Time line 1969: Unix is developed at AT&T 1983: The GNU Project launched 1991: Linux 0.01 ( 10k line of code, 1 user)‏ 1994: Linux 1.0 ( 170k line of code, 100 thousand user)‏ 1996: Linux 2.0 ( 400k line of code, 1.5 million user)‏ 1998: Linux 2.1. ( 1.5M line of code, 7.5 million user)‏ 1999: Linux 2.2. 12 million users 2008: A Promising Future

Linux Distributions Debian : (>1200 developers), community developed, strong, 15k packages. Ubuntu : for desktop users, based on Debian. Red Hat : Early star, now for enterprise works . Fedora : Sponsored by red hat, community supported. Centos : The Free (from charge) rebuild from RHEL. Suse : made by Novell, for enterprise. Lately there's a joint dev with Microsoft. OpenSuse : Open source alternative of Suse, community supported Slackware : Very Unix-like, Old but popular

Linux Principles - Everything is a file . Including hardware Configuration data stored in text Small, single-purpose programs Avoid Captive User Interfaces Ability to chain programs together to perform complex tasks .

End of Unit 1 Questions ... ? Summary : Open source and the right to modify The GNU Project and the Free Software Foundation Linus Torvalds and the Linux kernel Red Hat Enterprise Linux and the Fedora Project Basic Linux Principles

Objectives Upon completion of this unit, you should be able to: Log into a Red Hat Linux system Start X from a console Access the command line from X Change your password Understand the nature of root privileges Elevate your privileges Edit plain text files

Logging in to a Linux System Two types of log-in screens: 1- virtual consoles (text-based) 2- graphical log-in (called display managers)‏ log-in using log-in name and password Each user has a home directory for personal file storage /home

Switching between virtual consoles and the graphical environment A typical Linux system will run six virtual consoles and one graphical console -Server systems often have only virtual consoles -Desktops and workstations typically have both

Switch among virtual consoles by typing: Ctrl-Alt-F[1-> 6] Access the graphical console by typing Ctrl-Alt-F7

Elements of the X Window System -The X Window System is Linux's graphical subsystem -Xorg is the particular version of the X Window System used by Red Hat Open source implementation of X Look and behavior largely controlled by the desktop environment

Two desktop environments provided by Red-Hat: Is a Collections of applications that provide a graphical working environment with a consistent look and feel. GNOME:[ GNU Network Object Model Environment ] default desktop environment KDE: [K desktop environment ]an alternate desktop environment

Starting the X server -On some systems, the X server starts automatically at boot time -Otherwise, if systems come up in virtual consoles, users must start the X server manually -The X server must be pre-configured by the system administrator -Log into a virtual console and run startx The X server appears on Ctrl-Alt-F7

Changing Your Password Passwords control access to the system -Change the password the first time you log in -Change it regularly thereafter -Select a password that is hard to guess change your password using GNOME,navigate to System->Preferences->About Me click Password. To change your password from a terminal: passwd

The root user The root user: a special administrative account Also called the superuser root has near complete control over the system and a nearly unlimited capacity to damage it....! Do not login as root unless necessary Normal users potential to do damage is more limited

Changing Identities su - creates new shell as root sudo command runs command as root Requires prior configuration by a system- administrator id shows information on the current user

Editing text files The nano editor Easy to learn, easy to use Other editors: gedit , a simple graphical editor vim , an advanced, full feature editor gvim , a graphical version of the vim editor

End of Unit 2 Questions ...? Summary Login name and password startx gnome-terminal Passwd su nano

Objectives Upon completion of this unit, you should be able to : Execute commands at the prompt Explain the purpose and usage of some simple commands Use the built-in help resources in Linux

Shell ... ? Shell is a Unix term for the interactive user interface with an operating system. The shell is the layer of programming that understands and executes the commands a user enters on operating system. Shell types Bourne shell (sh)‏ C shell (csh)‏ TC shell (tcsh)‏ Korn shell (ksh)‏ Bourne Again SHell (bash)‏

what is shell command ? They are part of a shell, each shell (C Shell, Bourne Shell and Korn Shell) has a set of commands built into its program, the commands within each shell stay the same across Linux / Unix distributions . The user types shell commands at the shell prompt, the default of which is % for the C Shell, and $ for the Bourne Shell , Korn Shell . bash

Running Commands Commands have the following syntax: [ command O ptions arguments] Each item is separated by a space - Options modify a command's behavior Single-letter options usually preceded by “-” Can be passed as -a -b -c or -abc Full-word options usually preceded by “--” [ --help] - Arguments are file names or other data needed by the command Multiple Commands can be separated by “;”

Some Simple Commands date - display date and time cal - display calendar Ls list files Cd change directory

Getting Help Don't try to memorize everything! Many levels of help whatis -- with makewhatis command –help man and info /usr/share/doc/ Red Hat documentation Google IRC channels

The whatis Command Displays short descriptions of commands Uses a database that is updated nightly Often not available immediately after install $ whatis cal cal (1) - displays a calendar

The --help Option Displays usage summary and argument list Used by most, but not all, commands $ date --help Usage: date [OPTION]... [+FORMAT] or: date [-u|--utc|--universal] [MMDDhhmm] Display the current time in the given FORMAT, or set the system date.

Reading Usage Summaries Printed by -- help , man and others Used to describe the syntax of a command Arguments in [ ] are optional Arguments in CAPS or <> are variables Text followed by ... represents a list x|y|z means "x or y or z" -abc means "any mix of -a, -b or -c"

The man Command The collection of all man pages on a system is called the Linux Manual. The Linux is divided into sections, each of which covers a particular topic, and every man page is associated with exactly one of these sections. The sections are: Manual Sections. 1. General Commands 2. System Calls 3. Subroutines 4. Special Files 5. File Formats 6. Games 7. Macros and Conventions 8. Maintenence Commands man and man –k commands The file:// /usr/share/doc directory

Navigating man Pages While viewing a man page -Navigate with arrows, PgUp, PgDn -/text searches for text -n/N goes to next/previous match -q quits Searching the Manual man -k keyword lists all matching pages Uses whati s database

The info Command info pages are structured like a website. Each page is divided into “nodes”. Links to nodes are preceded by “*”. info [<command>] If you run info with no arguments you will be presented with a list links to the top nodes of every available info page.

While viewing an info page Navigate with arrows, pgUp, pgDown Tab Move to next link Enter Follow link the cursor is on n/p/u View next/previous/up-one node s[<text>] Search for text (default: last search)‏ q Quit Viewing page

Extended Documentation The file:// /usr/share/doc directory Sub directories for most installed packages Location of docs that do not fit elsewhere Example configuration files HTML/PDF/PS documentation http://www.redhat.com/docs

Red Hat Documentation Available on docs CD or Red Hat website Installation Guide Deployment Guide Virtualization Guide

End of Unit 3 Questions and Answers Summary Running Commands Getting Help

Unit 4 Browsing the Filesystem Linux File Hierarchy Concepts Some Important Directories File and Directory Names Absolute and Relative Pathnames Changing Directories [cd] Listing Directory Contents [ls] Copying Files and Directories [cp] Moving and Renaming Files and Directories [mv] Creating and Removing Files Creating and Removing Directories Using Nautilus [Moving , Copying ,Moving and Copying] Determining File Content [file]

Objectives U pon completion of this unit, you should be able to: Describe important elements of the filesystem hierarchy Copy, move, and remove files Create and view files Manage files with Nautil us

Linux File Hierarchy Concepts Files and directories are organized into single-rooted inverted tree structure File system begins at the root directory, represented by alone “ / ” (forward slash) character. Names are case-sensitive Paths are delimited by /

Basic File system Hierarchy Standard Directories / The root directory, the top-level directory in the FHS. All other directories are sub directories of root, which is always mounted on some partition. /bin Essential command line utilities. Should not be mounted separately; otherwise, it could be difficult to get to these utilities when using a rescue disk. /boot Includes Linux start up files, including the Linux kernel. The default, 100MB, is usually sufficient for a typical modular kernel and additional kernels that you might install. /dev Hardware and software device drivers for everything from floppy drives to terminals. Do not mount this directory on a separate partition. /etc Most basic configuration files. /home Home directories for almost every user.

/lib Program libraries for the kernel and various command line utilities. Do not mount this directory on a separate partition. /media The mount point for removable media, including floppy, DVDs. /mnt A legacy mount point; formerly used for removable media. /opt Common location for third-party application files. /proc Currently running kernel-related processes, including device assignments such as IRQ ports, I/O addresses, and DMA channels, as well as kernel configuration settings such as IP forwarding. /root The home directory of the root user. /sbin System administration commands. Don't mount this directory separately.

/selinux configured settings associated with Security Enhanced Linux. /tmp Temporary files. By default, Red Hat Enterprise Linux deletes all files in this directory periodically. . /usr Small programs accessible to all users. Includes many system administration commands and utilities. . /var Variable data, including log files and printer spools.

File and Directory Names Names may be up to 255 characters All characters are valid, except the forward-slash - It may be unwise to use certain special characters in file or directory names -Some characters should be protected with quotes when referencing them Names are case-sensitive Example: MAIL, Mail, mail, and mAiL

Absolute and Relative Path names Absolute path names Begin with a forward slash Complete "road map" to file location Can be used anytime you wish to specify a file name Relative path names Do not begin with a slash Specify location relative to your current working directory Can be used as a shorter way to specify a file name

current Working Directory Each shell and system process has a current working directory pwd Displays the absolute path to the shell's cwd

Changing Directories cd changes directories To an absolute or relative path: cd /home/joshua/work , cd project/docs To a directory one level up: cd .. To your home directory: cd To your previous working directory: cd -

Listing Directory Contents Lists contents of the current directory or a specified directory Usage : ls [options] [files_or_dirs] Example: ls -a (include hidden files)‏ ls -l (display extra information)‏ ls -R (recurse through directories)‏ ls -ld (directory and symlink information)‏

Copying Files and Directories cp - copy files and directories Usage: cp [options] file destination More than one file may be copied at a time if the destination is a directory: cp [options] file1 file2 destination

Copying Files and Directories:The Destination If the destination is a directory, the copy is placed there If the destination is a file, the copy overwrites the destination If the destination does not exist, the copy is renamed

Moving and Renaming Files and Directories mv - move and/or rename files and directories Usage: mv [options] file destination More than one file may be moved at a time if the destination is a directory: mv [options] file1 file2 destination

Creating and Removing Files touch - create empty files or update file timestamps rm - remove files Usage: rm [options] <file>... Example: rm -i file (interactive)‏ rm -r directory (recursive)‏ rm -f file (force)‏

Creating and Removing Directories mkdir creates directories rmdir removes empty directories rm -r recursively removes directory trees

Using Nautilus (GUI)‏ Gnome graphical file system browser Can run in spatial or browser mode Accessed via... Desktop icons Home: Your home directory Computer: Root file system, network resources and removable media Applications->System Tools->File Browser

Moving and Copying in Nautilus Drag-and-Drop Drag: Move on same filesystem, copy on different filesystem Drag + Ctrl: Always copy Drag + Alt: Ask whether to copy, move or create symbolic link (alias)‏ Context menu Right-click to rename, cut, copy or paste

Determining File Content Files can contain many types of data Check file type with file before opening to determine appropriate command or application to use file [options] <filename>...

End of Unit 4 Questions ...? Summary The Linux filesystem hierarchy Command-line file management tools The Nautilus file manager

Objectives Upon completion of this unit, you should be able to: Explain the Linux security model Explain the purpose of user and group accounts Read and set file permissions

Users Every user is assigned a unique User ID number (UID)‏ UID 0 identifies root Users' names and UIDs are stored in /etc/passwd Users are assigned a home directory and a program that is run when they log in (usually a shell)‏ Users cannot read, write or execute each others' files without permission

Groups Users are assigned to groups Each group is assigned a unique Group ID number (gid)‏ GIDs are stored in /etc/group Each user is given their own private group Can be added to other groups for additional access All users in a group can share files that belong to the group

Linux File Security Every file is owned by a UID and a GID Every process runs as a UID and one or more GIDs Usually determined by who runs the process Three access categories: -Processes running with the same UID as the file (user)‏ -Processes running with the same GID as the file (group)‏ -All other processes (other)‏

Permission Precedence If UID matches, user permissions apply Otherwise, If GID matches, group permissions apply If neither match, other permissions apply

Permission Types Four symbols are used when displaying permissions: r : permission to read a file or list a directory's contents w : permission to write to a file or create and remove files from a directory x: permission to execute a program or change into a directory and do a long listing of the directory - : no permission (in place of the r, w, or x)‏

Examining Permissions File permissions may be viewed using ls -l $ ls -l /bin/login -rwxr-xr-x 1 root root 19080 Apr 1 18:26 /bin/login File type and permissions represented by a 10 character string

Interpreting Permissions -rwxr-x--- 1 andersen trusted 2948 Oct 11 14:07 myscript Read, Write and Execute for the owner, andersen Read and Execute for members of the trusted group No access for all others

Changing File Ownership Only root can change a file's owner Only root or the owner can change a file'group Ownership is changed with chown : chown [-R] user_name file|directory Group-Ownership is changed with chgrp : chgrp [-R] group_name file|directory

Changing Permissions – Symbolic Method To change access modes: chmod [-R] mode file Where mode is: u,g or o for user, group and other + or - for grant or deny r, w or x for read, write and execute Examples: ugo+r: Grant read access to all o-wx: Deny write and execute to others

Changing Permissions – Numeric Method Uses a three-digit mode number -first digit specifies owner's permissions -second digit specifies group permissions -third digit represents others' permissions Permissions are calculated by adding: 4 (for read)‏ 2 (for write)‏ 1 (for execute)‏ Example: chmod 640 myfile

Changing Permissions – Nautilus Nautilus can be used to set the permissions and group membership of files and directories. In a Nautilus window, right-click on a file Select Properties from the context menu Select the Permissions tab

End of Unit 5 Questions ...? Summary All files are owned by one user and one group The mode of a file is made up of three permissions: user, the group and all others three permissions may be granted or denied: read, write and execute

Objectives Upon completion of this unit, you should be able to: Use command-line shortcuts Use command-line expansion Use history and editing tricks Use the gnome-terminal

Command Line Shortcuts File Globbing Globbing is wildcard expansion: - * - matches zero or more characters - ? - matches any single character - [0-9] - matches a range of numbers -[abc] - matches any of the character in the list - [^abc] - matches all except the characters in the list

Command Line Shortcuts The Tab Key Type Tab to complete command lines: For the command name, it will complete a command name For an argument, it will complete a file name Examples: $ xte<Tab> $ xterm $ ls myf<Tab> $ ls myfile.txt

Command Line Shortcuts History bash stores a history of commands you've entered, which can be used to repeat commands Use history command to see list of remembered commands $ history 14 cd /tmp 15 ls -l 16 cd 17 cp /etc/passwd . 18 vi passwd

More History Tricks Use the up and down keys to scroll through previous commands Type Ctrl-r to search for a command in command history. (reverse-i-search)`': To recall last argument from previous command: Esc,. (the escape key followed by a period)‏ Alt-. (hold down the alt key while pressing the period)‏

Command Line Expansion The tilde Tilde ( ~ )‏ May refer to your home directory $ cat ~/.bash_profile May refer to another user's home directory $ ls ~julie/public_html

Command Line Expansion Commands and Braced Sets Command Expansion:“()” Prints output of one command as an argument to another $ echo "This system's name is $(hostname)" This system's name is server1.example.com Brace Expansion: { } Shorthand for printing repetitive strings $ echo file{1,3,5} file1 file3 file5 $ rm -f file{1,3,5}

Command Editing Tricks Ctrl-a moves to beginning of line Ctrl-e moves to end of line Ctrl-u deletes to beginning of line Ctrl-k deletes to end of line Ctrl-arrow moves left or right by word

Gnome-terminal Applications->Accessories->Terminal Graphical terminal emulator that supports multiple "tabbed" shells Ctrl-Shift-t creates a new tab Ctrl-PgUp/PgDn switches to next/prev tab Ctrl-Shift-c copies selected text Ctrl-Shift-v pastes text to the prompt

Scripting Basics Shell scripts are text files that contain a series of commands or statements to be executed. Shell scripts are useful for: -Automating commonly used commands -Performing system administration and -troubleshooting -Creating simple applications -Manipulation of text or files

Creating Shell Scripts Step 1: Use such as vi to create a text file containing commands -First line contains #!/bin/bash Comment your scripts! Comments start with a #

Step 2: Make the script executable: $ chmod u+x myscript.sh To execute the new script: Place the script file in a directory in the executable path -OR-Specify the absolute or relative path to the script on the command line

Sample Shell Script #!/bin/bash # This script displays some information about your environment echo "Greetings. The date and time are $(date)" echo "Your working directory is: $(pwd)"

End of Unit 6 Questions ...? Summary Command expansion: $()‏ History recall: !string, !num Scripting Basics

Objectives Upon completion of this unit, you should be able to: Redirect I/O channels to files Connect commands using pipes Use the for loops to iterate over sets of values

Standard Input and Output Linux provides three I/O channels to Programs Standard input (STDIN) - keyboard by default Standard output (STDOUT) - terminal window by default Standard error (STDERR) - terminal window by default

Redirecting Output to a File STDOUT and STDERR can be redirected to files: command operator filename Supported operators include: > Redirect STDOUT to file 2> Redirect STDERR to file &> Redirect all output to file File contents are overwritten by default. >> appends.

Redirecting Output to a File Examples This command generates output and errors when run as non-root: $ find /etc -name passwd Operators can be used to store output and errors: $ find /etc -name passwd > find.out $ find /etc -name passwd 2> /dev/null $ find /etc -name passwd > find.out 2> find.err

Redirecting STDOUT to a Program (Piping)‏ Pipes (the | character) can connect commands: command1 | command2 Sends STDOUT of command1 to STDIN of command2 instead of the screen. STDERR is not forwarded across pipes Used to combine the functionality of multiple tools command1 | command2 | command3... etc

Redirecting STDOUT to a Program Examples less : View input one page at a time: $ ls -l /etc | less Input can be searched with / mail : Send input via email: $ echo "test email" | mail -s "test" user@example.com lpr : Send input to a printer $ echo "test print" | lpr $ echo "test print" | lpr -P printer_name

Combining Output and Errors Some operators affect both STDOUT and STDERR &> : Redirects all output: $ find /etc -name passwd &> find.all 2>&1 : Redirects STDERR to STDOUT Useful for sending all output through a pipe $ find /etc -name passwd 2>&1 | less () : Combines STDOUTs of multiple programs $ ( cal 2007 ; cal 2008 ) | less

Redirecting to Multiple Targets (tee)‏ $ command1 | tee filename | command2 Stores STDOUT of command1 in filename, then pipes to command2 Uses: Troubleshooting complex pipelines Simultaneous viewing and logging of output

Redirecting STDIN from a File Redirect standard input with < Some commands can accept data redirected to STDIN from a file: $ tr 'a-z' 'A-Z' < .bash_profile This command will translate the uppercase characters in .bash_profile to lowercase Equivalent to: $ cat .bash_profile | tr 'a-z' 'A-Z'

Sending Multiple Lines to STDIN Redirect multiple lines from keyboard to STDIN with <<WORD -All text until WORD is sent to STDIN Sometimes called a heretext $ mail -s "Please Call" jane@example.com <<END > Hi Jane, > Please give me a call when you get in. We may need > to do some maintenance on server1. > Details when you're on-site, > Boris > END

Scripting: for loops Performs actions on each member of a set of values Example: for NAME in joe jane julie do ADDRESS="$NAME@example.com" MESSAGE='Projects are due today!' echo $MESSAGE | mail -s Reminder $ADDRESS done

Can also use command-output and file lists: for num in $(seq 1 10)‏ Assigns 1-10 to $num seq X Y prints the numbers X through Y for file in *.ttxt Assigns names of text files to $file

End of Unit 7 Questions ...? Summary Standard I/O channels File redirection -Standard input (<)‏ -Standard Output (>)‏ -Standard Error (2>)‏ Pipes redirect standard output to standard input for loops can perform commands on items from a program's standard output or an explicit list

Objectives Upon completion of this unit, you should be able to: Use tools for extracting, analyzing and manipulating text data

Tools for Extracting Text File Contents: less and cat File Excerpts: head and tail Extract by Column: cut Extract by Keyword: grep

Viewing File Contents less and cat cat : dump one or more files to STDOUT Multiple files are concatenated together less : view file or STDIN one page at a timeUseful commands while viewing /text searches for text n/N jumps to the next/previous match v opens the file in a text editor less is the pager used by man

Viewing File Excerpts head and tail head : Display the first 10 lines of a file Use -n to change number of lines displayed tail : Display the last 10 lines of a file Use -n to change number of lines displayed Use -f to "follow" subsequent additions to the file *Very useful for monitoring log files!

Extracting Text by Keyword grep Prints lines of files or STDIN where a pattern is matched $ grep 'john' /etc/passwd $ date --help | grep year Use -i to search case-insensitively Use -n to print line numbers of matches Use -v to print lines not containing pattern Use -AX to include the X lines after each match Use -BX to include the X lines before each match

Extracting Text by Column cut Display specific columns of file or STDIN data $ cut -d: -f1 /etc/passwd $ grep root /etc/passwd | cut -d: -f7 Use -d to specify the column delimiter (default is TAB)‏ Use -f to specify the column to print Use -c to cut by characters $ cut -c2-5 /usr/share/dict/words

Tools for Analyzing Text Text Stats: wc Sorting Text: sort Comparing Files: diff and patch Spell Check: aspell

Gathering Text Statistics wc (word count)‏ Counts words, lines, bytes and characters Can act upon a file or STDIN $ wc story.txt 39 237 1901 story.txt Use -l for only line count Use -w for only word count Use -c for only byte count Use -m for character count (not displayed)‏

Sorting Text sort sort text to STDOUT - original file unchanged $ sort [options] file(s)‏ Common options -r performs a reverse (descending) sort -n performs a numeric sort -f ignores (folds) case of characters in strings -u (unique) removes duplicate lines in output -t c uses c as a field separator -k X sorts by c-delimited field X Can be used multiple times

Eliminating Duplicate Lines sort and uniq sort -u : removes duplicate lines from input uniq : removes duplicate adjacent lines from input Use -c to count number of occurrences Use with sort for best effect: $ sort userlist.txt | uniq

Duplicating File Changes patch diff output stored in a file is called a "patchfile" Use -u for "unified" diff, best in patchfiles patch duplicates changes in other files (use with care!)‏ Use -b to automatically back up changed files $ diff -u foo.conf-broken foo.conf-works > foo.patch $ patch -b foo.conf-broken foo.patch

Spell Checking with aspell Interactively spell-check files: $ aspell check letter.txt Non-interactively list mis-spelled words in STDIN $ aspell list < letter.txt $ aspell list < letter.txt | wc -l

Tools for Manipulating Text tr and sed Alter ( tr anslate) Characters: tr Converts characters in one set to corresponding characters in another set Only reads data from STDIN $ tr 'a-z' 'A-Z' < lowercase.txt Alter Strings: sed stream editor Performs search/replace operations on a stream of text Normally does not alter source file Use -i.bak to back-up and alter source file

Sed Examples Quote search and replace instructions! sed addresses sed 's/dog/cat/g' pets sed '1,50s/dog/cat/g' pets sed '/digby/,/duncan/s/dog/cat/g' pets Multiple sed instructions sed -e 's/dog/cat/' -e 's/hi/lo/' pets sed -f myedits pets

Special Characters for Complex Searches Regular Expressions ^ represents beginning of line $ represents end of line Character classes as in bash: [abc], [^abc] [[:upper:]], [^[:upper:]] Used by: grep, sed, less, others

End of Unit 8 Questions Summary Extracting Text cat, less, head, tail, grep, cut Analyzing Text wc, sort, uniq, diff, patch Manipulating Text tr, sed Special Search Characters ^, $, [abc], [^abc], [[:alpha:]], [^[:alpha:]] ,

Objectives Upon completion of this unit, you should be able to: Use the three primary modes of vi and vim Navigate text and enter Insert mode Change, delete, yank, and put text Undo changes Search a document Save and exit

Introducing vim Newer version of vi, the standard Unix text editor Executing vi runs vim by default gvim: Graphical version of vim Applications + Programming -> Vi iMproved Provided by vim-X11 package Advantages : Speed: Do more with fewer keystrokes Simplicity: No dependence on mouse/GUI Availability: Included with most Unix-like OSes Disadvantages Difficulty: Steeper learning curve than simpler editors Key bindings emphasize speed over intuitiveness

vim: A Modal Editor Keystroke behavior is dependent upon vim's "mode" Three main modes: Command Mode (default): Move cursor, cut/paste text, change mode Insert Mode : Modify text Ex Mode : Save, quit, etc Esc exits current mode EscEsc always returns to command mode

vim Basics To use vim, you must at least be able to Open a file Modify a file (insert mode)‏ Save a file (ex mode)‏

Opening a file in vim To start vi: vim filename If the file exists, the file is opened and the contents are displayed If the file does not exist, vi creates it when the edits are saved for the first time

Modifying a File Insert Mode i begins insert mode at the cursor Many other options exist A append to end of line I insert at beginning of line o insert new a line (below)‏ O insert new line (above)‏

Saving a File and Exiting vim Ex Mode Enter Ex Mode with : Creates a command prompt at bottom-left of screen Common write/quit commands: :w writes (saves) the file to disk :wq writes and quits :q! quits, even if changes are lost

Using Command Mode Default mode of vim Keys describe movement and text manipulation commands Commands repeat when preceded by a number Example Right Arrow moves right one character 5, Right Arrow moves right five characters

Moving Around Command Mode Move by character: Arrow Keys, h, j, k, l Non-arrow keys useful for remote connections to older systems Move by word: w, b Move by sentence: ), ( Move by paragraph: }, { Jump to line x: xG Jump to end: G

Search and Replace Command Mode Search as in less /, n, N Search/Replace as in sed Affects current line by default Use x,y ranges EX :1,5s/cat/dog/ or % for whole file EX :%s/cat/dog/gi

Manipulating Text Command Mode Change ( replace ) Delete ( cut ) Yank ( copy )‏ Line cc dd yy Letter cl dl yl Word cw dw yw Sentence ahead c) d) y)‏ Sentence behind c( d( y( Paragraph above c{ d{ y{ Paragraph below c} d} y}

Undoing Changes Command Mode u undo most recent change U undo all changes to the current line since the cursor landed on the line Ctrl-r redo last "undone" change

Visual Mode Allows selection of blocks of text v starts character-oriented highlighting V starts line-oriented highlighting Activated with mouse in gvim Visual keys can be used in conjunction with movement keys: w, ), }, arrows, etc Highlighted text can be deleted, yanked, changed, filtered, search/replaced, etc.

Using multiple "windows" Multiple documents can be viewed in a single vim screen. Ctrl-w, s splits the screen horizontally Ctrl-w, v splits the screen vertically Ctrl-w, Arrow moves between windows Ex-mode instructions always affect the current window :help windows displays more window commands

Configuring vi and vim Configuring on the fly :set or :set all Configuring permanently ~/.vimrc or ~/.exrc A few common configuration items :set number :set autoindent :set textwidth=65 (vim only)‏ :set wrapmargin=15 :set ignorcase Run :help option-list for a complete list

Learning more vi/vim built-in help :help :help topic Use :q to exit help vimtutor command

End of Unit 9 Questions ...? Summary Use the three primary modes of vi and vim Move the cursor and enter Insert mode Change, delete, yank, and put text Undo changes Search a document Save and exit

Objectives Upon completion of this unit, you should be able to: Configure date, network and printer settings Send text to the printer Set the system's date and time

TCP/IP Network Configuration Important network settings: IP Configuration Device Activation DNS Configuration Default Gateway

Managing Ethernet Connections Network interfaces are named sequentially: eth0, eth1, etc Multiple addresses can be assigned to a device with aliases Aliases are labeled eth0:1, eth0:2, etc, Aliases are treated like separate interfaces View interface configuration with ifconfig [ethX] Enable interface with ifup ethX Disable interface with ifdown ethX

Graphical Network Configuration system-config-network System->Administration->Network Activate/Deactivate interfaces Assign IP Addresses/DHCP Modify DNS settings Modify gateway address

Network Configuration Files Ethernet Devices Device configuration is stored in text files /etc/sysconfig/network-scripts/ifcfg-ethX Complete list of options in /usr/share/doc/ initscripts-*/sysconfig.txt Dynamic Configuration Static Configuration DEVICE=ethX DEVICE=ethX HWADDR=0:02:8A:A6:30:45 HWADDR=0:02:8A:A6:30:45 BOOTPROTO=dhcp IPADDR=192.168.0.254 ONBOOT=yes NETMASK=255.255.255.0 Type=Ethernet GATEWAY=192.168.2.254 ONBOOT=yes Type=Ethernet

Network Configuration Files Other Global Network Settings Global Settings in /etc/sysconfig/network Many may be provided by DHCP GATEWAY can be overridden in ifcfg file NETWORKING=yes HOSTNAME=server1.example.com GATEWAY=192.168.2.254

Network Configuration Files DNS Configuration Domain Name Service translates hostnames to network addresses Server address is specified by dhcp or in /etc/resolv.conf search example.com cracker.org nameserver 192.168.0.254 nameserver 192.168.1.254

Printing in Linux Printers may be local or networked Print requests are sent to queues Queued jobs are sent to the printer on a first come first served basis Jobs may be canceled before or during printing

System-config-printer System->Administration->Printing Supported printer connections: Local (parallel or usb)‏ Unix/Linux print server Windows print server Netware print server HP JetDirect Configuration stored in /etc/cups/printers.conf

Printing Commands lpr sends a job to the queue to be printed Accepts ASCII, PostScript, PDF, others lpq views the contents of the queue lprm removes a job from the queue System V printing commands such as lp, lpstat and cancel are also supported

Printing Utilities evince views PDF documents lpstat -a lists configured printers enscript and a2ps convert text to PostScript ps2pdf converts PostScript to PDF mpage prints multiple pages per sheet

Setting the System's Date and Time GUI: system-config-date System->Administration->Date & Time Can set date/time manually or use NTP Additional NTP servers can be added Can use local time or UTC CLI: date [MMDDhhmm[[CC]YY][.ss]] # date 01011330 # date 010113302007.05

End of Unit 10 Questions ...? Summary system-config-network /etc/sysconfig/network-scripts/* ifup, ifdown lpr sends text to the printer date configures date/time from CLI system-config-date configures date/time from GUI

Objectives Upon completion of this unit, you should be able to: Explain what a process is Describe how to manage processes Use job control tools

What is a Process? A process is a set of instructions loaded into memory Numeric Process ID (PID) used for identification UID, GID and SELinux context determines filesystem access Normally inherited from the executing user

Listing Processes View Process information with ps Shows processes from the current terminal by default -a includes processes on all terminals -x includes processes not attached to terminals -u prints process owner information -f prints process parentage -o PROPERTY,... prints custom information: pid, comm, %cpu, %mem, state, tty, euser, ruser

Finding Processes Most flexible: ps options | othercommands ps axo comm,tty | grep ttyS0 By predefined patterns: pgrep $ pgrep -U root $ pgrep -G student By exact program name: pidof $ pidof bash

Signals Most fundamental inter-process communication Sent directly to processes, no user-interface required Programs associate actions with each signal -Signals are specified by name or number when sent: Signal 15 , TERM (default) - Terminate cleanly Signal 9 , KILL - Terminate immediately Signal 1 , HUP - Re-read configuration files man 7 signal shows complete list

Sending Signals to Processes By PID: kill [signal] pid ... By Name: killall [signal] comm ... By pattern: pkill [-signal] pattern

Scheduling Priority Scheduling priority determines access to the CPU Priority is affected by a process' nice value Values range from -20 to 19 but default to 0 Lower nice value means higher CPU priority Viewed with ps -o comm,nice

Altering Scheduling Priority Nice values may be altered... When starting a process: $ nice -n 5 command After starting: $ renice 5 PID Only root may decrease nice values

Interactive Process Management Tools CLI: top GUI: gnome-system-monitor Capabilities Display real-time process information Allow sorting, killing and re-nicing

Job Control Run a process in the background Append an ampersand to the command line: firefox & Temporarily halt a running program Use Ctrl-z or send signal 17 (STOP)‏ Manage background or suspended jobs List job numbers and names: jobs Resume in the background: bg [%jobnum] Resume in the foreground: fg [%jobnum] Send a signal: kill [-SIGNAL] [%jobnum]

Scheduling a Process To Execute Later One-time jobs use at , recurring jobs use crontab Create at time crontab -e List at -l crontab -l Details at -c jobnum N/A Remove at -d jobnum crontab -r Edit N/A crontab -e Non-redirected output is mailed to the user root can modify jobs for other users

Crontab File Format Entry consists of five space-delimited fields followed by a command line One entry per line, no limit to line length Fields are:- minute, hour, day of month, month, and day of week Comment lines begin with # for details See man 5 crontab

Grouping Commands Two ways to group commands: Compound: date; who | wc -l Commands run back-to-back Subshell: (date; who | wc -l) >> /tmp/trace All output is sent to a single STDOUT and STDERR

Exit Status Processes report success or failure with an exit status 0 for success, 1-255 for failure $? stores the exit status of the most recent command exit [num] terminates and sets status to num Example: $ ping -c1 -W1 station999 &> /dev/null $ echo $? 2

Conditional Execution Operators Commands can be run conditionally based on exit status && represents conditional AND THEN || represents conditional OR ELSE Examples: $ grep -q no_such_user /etc/passwd || echo 'No such user' $ ping -c1 -W2 station1 &> /dev/null && echo "station1 is up" || $(echo 'station1 is unreachable'; exit 1)‏ station1 is up

The test Command Evaluates boolean statements for use in conditional execution Returns 0 for true Returns 1 for false Examples in long form: $ test "$A" = "$B" && echo "Strings are equal" $ test "$A" -eq "$B" && echo "Integers are equal" Examples in shorthand notation: $ [ "$A" = "$B" ] && echo "Strings are equal" $ [ "$A" -eq "$B" ] && echo "Integers are equal"

File Tests File tests: -f tests to see if a file exists and is a regular file -d tests to see if a file exists and is a directory -x tests to see if a file exists and is executable [ -f ~/lib/functions ] && source ~/lib/functions

Scripting: if Statements Execute instructions based on the exit status of a command if ping -c1 -w2 localhost &> /dev/null; then echo 'localhost is UP' elif grep "localhost" ~/maintenance.txt &> /dev/null; then echo 'localhost is undergoing maintenance' else echo 'localhost is unexpectedly DOWN!' exit 1 fi

End of Unit 11 Questions ...? Summary A process is any set of instructions in memory Processes are managed with: ps, kill, top, gnome- system-monitor Suspend jobs with Ctrl-z, manage with fg, bg

Objectives Upon completion of this unit, you should be able to: Know how to use local and environment variables Know how to inhibit variable expansion Know how to create aliases Understand how the shell parses a command line Know how to configure start up files Know how to handle input with the read command and positional parameters

Bash Variables Variables are named values Useful for storing data or command output Set with VARIABLE=VALUE Referenced with $VARIABLE $ HI="Hello, and welcome to $(hostname)." $ echo $HI Hello, and welcome to stationX.

Environment Variables Variables are local to a single shell by default Environment variables are inherited by child shells Set with export VARIABLE=VALUE Accessed by some programs for configuration

Aliases Aliases let you create shortcuts to commands $ alias dir='ls -laF' Use alias by itself to see all set aliases Use alias followed by an alias name to see alias value $ alias dir alias dir='ls -laF'

How bash Expands a Command Line 1. Split the line into words 2. Expand aliases 3. Expand curly-brace statements ({})‏ 4. Expand tilde statements (~)‏ 5. Expand variables ($)‏ 6. Command-substituation ($() and ``)‏ 7. Split the line into words again 8. Expand file globs (*, ?, [abc], etc)‏ 9. Prepare I/O redirections (<, >)‏ 10. Run the command!

Preventing Expansion Backslash ( \ ) makes the next character literal $ echo Your cost: \$5.00 Your cost: $5.00 Quoting prevents expansion Single quotes (') inhibit all expansion Double quotes (") inhibit all expansion, except: $ (dollar sign) - variable expansion ` (backquotes) - command substitution \ (backslash) - single character inhibition ! (exclamation point) - history substitution

Login vs non-login shells Startup is configured differently for login and non-login shells Login shells are: Any shell created at login (includes X login)‏ su - Non-login shells are: su graphical terminals executed scripts any other bash instances

Bash start up tasks: profile Stored in /etc/profile (global) and ~/. bash_profile (user)‏ Run for login shells only Used for Setting environment variables Running commands (eg mail-checker script)‏

Bash start up tasks: bashrc Stored in /etc/bashrc (global) and ~/.bashrc (user)‏ Run for all shells Used for Setting local variables Defining aliases

Bash exit tasks Stored in ~/.bash_logout (user)‏ Run when a login shell exits Used for Creating automatic backups Cleaning out temporary files

Scripting: Taking input with positional Parameters Positional parameters are special variables that hold the command-line arguments to the script. The positional parameters available are $1,$2, $3, etc. . These are normally assigned to more meaningful variable names to improve clarity. $* holds all command-line arguments $# holds the number of command-line arguments

Scripting: Taking input with the read command Use read to assign input values to one or more shell variables: -p designates prompt to display read reads from standard input and assigns one word to each variable Any leftover words are assigned to the last variable read -p "Enter a filename: " FILE

End of Unit 12 Questions ...? Summary local and environment variables command line parsing configuring the shell environment positional parameters and the read command

Objectives Upon completion of this unit, you should be able to: Use locate Use find Use the Gnome Search tool

Locate Queries a pre-built database of paths to files on the system Database must be updated by administrator Full path is searched, not just filename May only search directories where the user has read and execute permission

locate Examples locate foo Search for files with "foo" in the name or path locate -r '\.foo$' Regex search for files ending in ".foo" Useful options -i performs a case-insensitive search -n X lists only the first X matches

Find find [directory...] [criteria...] Searches directory trees in real-time Slower but more accurate than locate CWD is used if no starting directory given All files are matched if no criteria given Can execute commands on found files May only search directories where the user has read and execute permission

Basic find Examples find -name snow.png Search for files named snow.png find -iname snow.png Case-insensitive search for files named snow.png, Snow.png, SNOW.PNG, etc find -user joe -group joe Search for files owned by the user joe and the group joe

find and Logical Operators Criteria are ANDed together by default. Can be OR'd or negated with -o and -not Parentheses can be used to determine logic order, but must be escaped in bash. find -user joe -not -group joe find -user joe -o -user jane find -not $ -user joe -o -user jane $‏

find and Permissions Can match ownership by name or id find / -user joe -o -uid 500 Can match octal or symbolic permissions find -perm 755 matches if mode is exactly 755 find -perm +222 matches if anyone can write find -perm -222 matches if everyone can write find -perm -002 matches if other can write

find and Numeric Criteria Many find criteria take numeric values find -size 1024k Files with a size of exactly 1megabyte find -size +1024k Files with a size over 1 megabyte find -size -1024k Files with a size less than 1 megabyte

find and Access Times find can match by inode timestamps -atime when file was last read -mtime when file data last changed -ctime when file data or metadata last changed Value given is in days find -ctime -10 Files modified less than 10 days ago

Executing Commands with find Commands can be executed on found files Command must be preceded with -exec or -ok -ok prompts before acting on each file Command must end with Space\; Can use {} as a filename placeholder find -size +102400k -ok gzip {} \;

find Execution Examples find -name "*.cconf" -exec cp {} {}.orig\; Back up configuration files, adding a .orig extension find /tmp -ctime +3 -user joe -ok rm {}\; Prompt to remove Joe's tmp files that are over 3 days old find ~ -perm +o+w -exec chmod o-w {} \; Fix other-writable files in your home directory

The Gnome Search Tool Places->Search for Files... Graphical tool for searching by name content owner/group size modification time

End of Unit 13 Questions ...? Summary Use locate to quickly find files that are not new Use find to search based on very specific criteria and optionally run commands on matching files Use the Gnome Search Tool for an intuitive, but powerful GUI search tool.

Objectives Upon completion of this unit, you should be able to: Browse the web Exchange email and instant messages Access a Linux system remotely Transfer files between systems Use network diagnostic tools

Web Clients Firefox Other web browsers Non-GUI web browsers wget

Firefox Fast, lightweight, feature-rich web browser Tabbed browsing Popup blocking Cookie management Multi-engine search bar Support for many popular plug-ins Themes and Extensions

Non-GUI Web Browsers links Provided by the elinks rpm Full support for frames and ssl Examples links http://www.redhat.com links -dump http://www.redhat.com links -source http://www.redhat.com

Wget Retrieves files via HTTP and FTP Non-interactive - useful in shell scripts Can follow links and traverse directory trees on the remote server - useful for mirroring web and FTP sites

Email and Messaging Evolution Other email clients Non-GUI email clients Gaim

Evolution Default email and groupware tool Provides email, calendar, tasks and contacts Can maintain multiple accounts at once Supports GnuPG encryption and signatures "Trainable" bayesian spam filters Task/Calendar notifications in Gnome clock Can sync with many PDAs

Configuring Evolution Defining accounts Tools->Settings->Mail Accounts Supports IMAP, pop, Novell Groupware, Usenet and local email accounts MS Exchange support via plug-in Provided by evolution-connector rpm Install before configuring other accounts

Other GUI Mail Clients Thunderbird Standalone Mozilla email client Kmail KDE email client

Non-GUI Mail Clients mutt Supports pop, imap and local mailboxes Highly configurable Mappable hotkeys Message threading and colorizing GnuPG integration Context-sensitive help with '?'

Gaim Multi-protocol Instant messaging client Available in Red Hat Enterprise Linux Client Supports AIM, MSN, ICQ, Yahoo, Jabber, Gadu-Gadu, SILC, GroupWise Messenger, IRC and Zephyr networks. Plugins can be used to add functionality.

Open Ssh: Secure Remote Shell Secure replacement for older remote-access tools Allows authenticated, encrypted access to remote systems ssh [user@]hostname ssh [user@]hostname command

scp: Secure File Transfer Secure replacement for rcp Layered on top of ssh scp source destination Remote files can be specified using: [user@]host:/path/to/file Use -r to enable recursion Use -p to preserve times and permissions Use -C to compress datastream

rsync: Efficient File Sync Efficiently copies files to or from remote systems Uses secure ssh connections for transport rsync *.conf barney:/home/joe/configs/ Faster than scp - copies differences in like files

Open Ssh Key-based Authentication Optional, password-less, but still secure, authentication Uses two keys generated by ssh-keygen: private key stays on your system Usually passphrase-protected (recommended )‏ public key is copied to destination with ssh-copy-id ssh-copy-id [user@]host

Open Ssh Key-based Authentication continued An authentication agent stores decrypted private keys Thus, passphrase only needs to be entered once An agent is provided automatically in GNOME Otherwise, run ssh-agent bash Keys are added to the agent with ssh-add

FTP Clients CLI: lftp $ lftp ftp.example.com $ lftp -u joe ftp.example.com Automated transfers with lftpget GUI: gFTP Applications->Internet->gFTP Allows Drag-and-Drop transfers Anonymous or authenticated access Optional secure transfer via ssh (sftp)‏

Smbclient FTP-like client to access SMB/CIFS resources Examples: smbclient -L server1 lists shares on server1 smbclient -U student //server1/homes accesses a share

File Transfer with Nautilus File/Connect to Server Graphically browse with multiple protocols Allows drag-and-drop file transfers Supported connection types: FTP, SFTP, SMB, WebDAV, Secure WebDAV Can also connect via url: File/Open Location

Xorg Clients All graphical applications are X clients Can connect to remote X severs via tcp/ip Data is not encrypted but can be tunneled securely over an ssh connection ssh -X user@hostB xterm & xterm will display on hostA's X server Transmitted data will be encrypted through the ssh connection

Network Diagnostic Tools ping traceroute host dig netstat gnome-nettool (GUI)‏

End of Unit 14 Questions ...? Summary Firefox, Evolution and Mutt Basic network diagnostic tools The importance of secure network clients

Objectives Upon completion of this unit, you should be able to: Describe where Linux stores user, group and password information Change identities Set default permissions Use special permissions

User and Group ID Numbers User names map to user ID numbers Group names map to group ID numbers Data stored on the hard disk is stored numerically

/etc/passwd, /etc/shadow, and /etc/group files Authentication information is stored in plain text files: /etc/passwd /etc/shadow /etc/group /etc/gshadow

User management tools Graphical tools system-config-users Command-line useradd usermod userdel [-r]

System Users and Groups Server programs such as web or print servers typically run as unprivileged users, not as root Examples: daemon, mail, lp, nobody Running programs in this way limits the amount of damage any single program can do to the system

Monitoring Logins Connected users: w Recent Logins: last, lastb

Default Permissions Default permission for directories is 777 minus umask Default permission for files is the directory default without execute permission. umask is set with the umask command. Non-privileged users' umask is 002 Files will have permissions of 664 Directories will have permissions of 775 root's umask is 022

Special Permissions for Executables Special permissions for executables: suid : command run with permissions of the owner of the command, not executor of the command sgid : command runs with group affiliation of the group of the command

Special Permissions for Directories Special permissions for directories: sticky bit: files in directories with the sticky bit set can only be removed by the owner and root, regardless of the write permissions of the directory sgid: files created in directories with the sgid bit set have group affiliations of the group of the directory

End of Unit 15 Questions ...? Summary User information is stored in /etc/passwd Group information is stored in /etc/group Special Permissions: Sticky Bit, SetUID, SetGID

Objectives Upon completion of this unit, you should be able to: Describe how filesystem information is organized Describe the function of dentries and inodes Describe how cp, mv, and rm work at the inode level Create symbolic links and hard links Access removable media Create archives using tar and gzip

Partitions and Filesystems Disk drives are divided into partitions Partitions are formatted with filesystems allowing users to store data Default filesystem: ext3, the Third Extended Linux Filesystem Other common filesystems: ext2 and msdos (typically used for floppies)‏ iso9660 (typically used for CDs)‏ GFS and GFS2 (typically for SANs)‏

Inodes An inode table contains a list of all files in an ext2 or ext3 filesystem An inode (index node) is an entry in the table, containing information about a file (the metadata), including: file type, permissions, UID, GID the link count (count of path names pointing to this file)‏ the file's size and various time stamps pointers to the file's data blocks on disk other data about the file

Directories The computer's reference for a file is the inode number The human way to reference a file is by file name A directory is a mapping between the human name for the file and the computer's inode number

cp and inodes The cp command: 1. Allocates a free inode number, placing a new entry in the inode table 2. Creates a dentry in the directory, associating a name with the inode number 3. Copies data into the new file

mv and inodes If the destination of the mv command is onthe same file system as the source, the mv command: 1. Creates a new directory entry with the new file name 2. Deletes the old directory entry with the old file name Has no impact on the inode table (except for a time stamp) or the location of data on the disk: no data is moved! If the destination is a different filesystem, mv acts as a copy and remove

rm and inodes The rm command: 1. Decrements the link count, thus freeing the inode number to be reused 2. Places data blocks on the free list 3. Removes the directory entry Data is not actually removed, but will be overwritten when the data blocks are used by another file

Hard Links hard link adds an additional pathname to reference a single file One physical file on the filesystem Each directory references the same inode number Increments the link count The rm command decrements the link count File exists as long as at least one link remains When the link count is zero, the file is removed Cannot span drives or partitions Syntax: ln filename [linkname]

Symbolic (or Soft) Links A symbolic link points to another file ls -l displays the link name and the referenced file lrwxrwxrwx 1 joe joe 11 Sep 25 18:02 pf -> /etc/passwd File type: l for symbolic link The content of a symbolic link is the name of the file that it references Syntax: ln -s filename linkname

The Seven Fundamental Filetypes ls -l symbol File Type - regular file d directory l symbolic link b block special file c character special file p named pipe s socket

Checking Free Space df - Reports disk space usage Reports total kilobytes, kilobytes used, kilobytes free per file system -h and -H display sizes in easier to read units du - Reports disk space usage Reports kilobytes used per directory Includes subtotals for each subdirectory -s option only reports single directorysummary Also takes -h and -H options Applications->System Tools->Disk Usage Analyzer or baobab - Reports disk space usage graphically

Removable Media Mounting means making a foreign filesystem look like part of the main tree. Before accessing, media must be mounted Before removing, media must be unmounted By default, non-root users may only mount certain devices (cd, dvd, floppy, usb, etc)‏ Mountpoints are usually under /media

Mounting CDs and DVDs Automatically mounted in Gnome/KDE Otherwise, must be manually mounted CD/DVD Reader mount /media/cdrom CD/DVD Writer mount /media/cdrecorder eject command unmounts and ejects the disk

Mounting USB Media Detected by the kernel as SCSI devices /dev/sdaX or /dev/sdbX or similar Automatically mounted in Gnome/KDE Icon created in Computer window Mounted under /media/Device ID Device ID is built into device by vendor

Archiving Files and Compressing Archives Archiving places many files into one target file Easier to back up, store, and transfer tar - standard Linux archiving command Archives are commonly compressed Algorithm applied that compresses file Uncompressing restores the original file tar natively supports compression using gzip and gunzip, or bzip2 and bunzip2

Creating, Listing, and Extracting File Archives Action arguments (one is required): -c create an archive -t list an archive -x extract files from an archive Typically required: -f archivename name of file archive Optional arguments: -z use gzip compression -j use bzip2 compression -v be verbose

Creating File Archives: Other Tools zip and unzip Supports pkzip-compatible archives Example: zip etc.zip /etc unzip etc.zip file-roller Graphical, multi-format archiving tool

End of Unit 16 Questions ...? Summary Linux filesystem structure Using removable media Using unformatted floppies Archiving and compression

Objectives Upon completion of this unit, you should be able to: Explain the process of installing Red Hat Enterprise Linux Identify services, their status and be able to manage the runlevels which start and stop them Install software using multiple installation methods Understand the basic principles of Red Hat Enterprise Linux security, firewalls, and SELinux

Planning an Installation What hardware does the system use? Check hardware compatibility Read the RELEASE-NOTES file on the first CD or at http://www.redhat.com Provides valuable summary of features and gotchas

Performing an Installation Installer can be started from: CD-ROM or DVD-ROM USB Device Network (PXE)‏ Supported installation sources: Network Server (ftp, http or nfs)‏ CD-ROM or DVD-ROM Hard Disk

Managing Services What is a service? Graphical Interface to Service Management system-config-services Command Line Interface to Service Management service chkconfig

Managing Software Software is provided as RPM packages Easy installation and removal Software information stored in a local database Packages are provided by Red Hat Network Centralized management of multiple systems Easy retrieval of errata packages Systems must be registered first Custom package repositories may also be used

The Yum Package Management Tool Front-end to rpm, replacing up2date Configuration in /etc/yum.conf and / etc/yum.repos.d/ Used to install, remove and list software yum install packagename yum remove packagename yum update packagename yum list available yum list installed

Graphical Package Management pup Applications->System Tools->Software Updater List and install software updates pirut Applications->Add/Remove Software View, install and un-install other packages

Securing the System Basic security principles Avoid running services that you do not need Limit access to services that are running Avoid using services that send data unencrypted over the network such as instant messaging, pop, imap, and telnet

SELinux Kernel-level security system All processes and files have a context SELinux Policydictates how processes and files may interact based on context Policy rules cannot be overridden Default policy does not apply to all services

Managing SELinux SELinux errors are logged in the System Log SELinux can be disabled in an emergency Disabling SELinux is discouraged! System->Administration->Security Level and Firewall, SELinux tab

Packet Filtering Network traffic is divided into packets Each packet has source/destination data Firewalls selectively block packets

Firewall and SELinux Configuration system-config-securitylevel System-> Administration->Security Level and Firewall Selectively allow incoming connections by port Specify interfaces to trust all traffic from Responses to outbound queries always accepted More advanced configuration possible with other tools

End of Unit 17 Questions ...? Summary System Installation Process Managing Services Software Installation Tools System Security

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