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====== LPIC-1 / Linux+  Cheat Sheet ======

===== LX0-101 =====

==== 101 System Architecture 14% ====

===  101.1 Determine and Configure hardware settings (LCN-3 CTL-3) ===
  * Enable and disable integrated peripherals
  * Configure systems with or without external peripherals such as keyboards
   * Differentiate between the various types of mass storage devices
   * Set the correct hardware ID for different devices, especially the boot device
   * Know the differences between coldplug and hotplug devices
   * Determine hardware resources for devices
   * Tools and utilities to list various hardware information (e.g., lsusb, lspci, etc.)
  * Tools and utilities to manipulate USB devices
  * Conceptual understanding of sysfs, udev, hald, dbus
  * Terms: /sys, /proc, /dev, modprobe, lsmod, lspci, lsusb

== Notes ==

* BIOS - Basic I/O System - systim init, memory testing, low-level system-config, OS boot order (CD, floppy, HD, PXE), internal HW clock
  * /proc fs is kernel's status repository: interrupts, dma, ioports
  * Universal Serial Bus (USB)
    * //lsusb [-t] [-vv] // - t-tree view, vv-very verbose
    * Open Host Controller Interface (OHCI) - USB 1.1
    * Universal Host Controller Interface (UHCI) - USB 1.1 - 12 MBps - low+full speed
    * Enhanced Host Controller Interface (EHCI) - USB 2.0 - 480 MBps - high speed
    * Extensible Host Controller Interface (XHCI) - USB 3.0 - 4 GBps - super speed
    * Wireless Host Controller Interface (WHCI) - Wireless USB 1.0 - 480 MBps
    * Effective speed is lowest speed of device, cable and hub
    * Classes of USB devices :
      * Human Interface Device (HID) - Input devices: mice, keyboards, etc.)
      * Communications device - Modems
      * Mass storage device - Disk devices, flash readers, etc.
      * Audio - Sound devices
      * IrDA - Infrared devices
      * Printer - Printers and USB-to-parallel cables
    * Linux kernel supported USB in v2.3.x, backported to 2.2.18
    * Linux drivers may be host controller drivers (e.g. usb-ohci.o), class drivers (e.g. hid.o, usb-storage.o, printer.o, audio.o) or device-specific drivers
    * usbcore.o -> host controller driver -> class/device driver
    * Modularized USB drivers are loaded by the generic /sbin/hotplug kernel support
  * //lsdev// - shows hardware including IRQ info, I/O ports and DMA channels
  *  //lspci [-t] [-vv]// - info about system’s PCI buses and installed PCI devices
  * A module is dynamically linked into the running kernel when it is loaded
    * //insmod/rmmod// - insert/remove mocule, no dependency checking
    * //modprobe [-r] [-a] [-t type]// - list, insert or remove modules. Does dependency checking.
    * //lsmod// - list modules //modinfo module-object-file.o// - info about a module file
  * sysfs is a RAM-based filesystem derived from ramfs. It provides a means to export kernel data structures to  user space. // mount -t sysfs sysfs /sys//
  * The udev process uses sysfs info to create dynamic device files as kernel modules are loaded. /etc/udev.d holds rules to be applied when adding or removing a device.
  * D-Bus is an IPC system that uses sysfs to implement a message bus daemon used for broadcasting system events e.g.“new device added” or “printer queue changed”.
  * hal was a hw abstraction layer (hw access API) on top of udev using D-Bus. It has been deprecated and rolled into udev and the kernel.

===  101.2 Boot the System (LCN-4 CTL-5) ===
  * Provide common commands to the boot loader and options to the kernel at boot time
  * Demonstrate knowledge of the boot sequence from BIOS to boot completion
  * Check boot events in the log file
  * Terms: /var/log/messages, dmesg, BIOS, bootloader, kernel, init

== Notes ==
  * Boot Loader (LILO or GRUB) launches the linux kernel, passing kernel parameters if needed (/etc/lilo.conf | /boot/grub/menu.lst | /boot/grub/grub.conf)
  * Module options (as well as aliases and post-install and pre-remove actions) are stored in /etc/modules.conf .
  * //dmesg// displays kernel messages logged at last system boot.
  * // /var/log/messages // contains all syslog messages.

=== 101.3 Change runlevels and shutdown or reboot system (LCN-4 CTL-5) ===
  * Set the default run level
  * Change between run levels including single user mode
  * Shutdown and reboot from the command line
  * Alert users before switching run levels or other major system events
  * Properly terminate processes
  * Knowledge of basic features of systemd and Upstart
  * Terms: /etc/inittab, shutdown, init, /etc/init.d, telinit

== Notes ==
  * When linux boots, first process is the //init// process which selects and switches to default runlevel.
  * Runlevels - 0=shutdown, 1/s/S=single-user_maintenance, 2=multi-user, 3=multi-user_no-X, 5=multi-user_with-X 6=reboot
  * On Debian, 2 is default and 3,5 are not used. On Redhat, 3 is the default.
  * /etc/rc script to change runlevels on redhat (also init/telinit script)
  * /etc/rc.sysinit (Redhat) or /etc/init.d/rcS (Debian) - system init script launched by init before system daemons
  * /etc/rc.local- local startup actions called at end of startup
  * /etc/init.d contains startup/shutdown scripts for all system services
  * /etc/rc0.d - /etc/rc6.d contain softlinks KNNservice or SNNservice specifying whether to start or stop services and in what order for that runlevel (done by init process). Kills done before starts.
  * /etc/inittab contains "id:N:initdefault:" for default runlevel N
  * //runlevel// shows current and previous runlevel
  * //shutdown [options] time [warning message]//  - -f=fastboot -h=halt -r=reboot -F=force-startup-checks -k=just-send-warning . Time is "now" or "+N" in N minutes or absolute time e.g. 23:58.
==== 102 Installation and Package Management 18% ====

=== 102.1 Design hard disk layout (LCN-5 CTL-3) ===
  * Allocate filesystems and swap space to separate partitions or disks
  * Tailor the design to the intended use of the system
  * Ensure the /boot partition conforms to the hardware architecture requirements for booting
  * Knowledge of basic features of LVM
  * Terms: / (root) filesystem, /var filesystem, /home filesystem, swap space, mount points, partitions

==Notes==

* choosing a disk layout for linux depends on amount of disk space, purpose of the system, size of the system and backup strategy. Some general guidelines are
    * If diskspace is limited, just /boot, / and /swap
    * /boot is a separate 50MB partition because older kernels/BIOS require kernels under a 1024 cylinder limit.
    * For larger systems keep / smaller/simpler to reduce risk of corruption.
    * Can use separate partitions for /var (to isolate system logs), /tmp (to isolate tempfiles), /home (for backup and RAIDing of user's data)
    * Using a separate partition for /usr allows it to be shared via read-only NFS which allows for saving space and easier maintenance of apps/updates.
  * Superblock on filesystem contains critical metadata so multiple redundant copies are kept.
  * Filesystems must be mounted (listed in filesystem table) before being accessible. /etc/fstab is a list of filesystems to mount on boot up.
  * Master Boot Record on first 512 bytes of first sector of disk contains info on partitions and bootup. Can be backed up and restored with <code>
dd if=/dev/hda of=~/mbr.txt count=1 bs=512
dd if=~/mbr.txt of=/dev/hda count=1 bs=512
</code>
  * To backup/restore just the partition layout, use sfdisk <code>
sfdisk -d /dev/hda > partition_backup.txt
sfdisk /dev/hda < partition_backup.txt
</code>
  * Linux may also be booted from Live USB which allows for persistent modifications. If the BIOS does nto support this, a bootable CD can be used first.
  * Swap space allows main memory to be temporarily copied to disk. As a starting point set swap to twice the memory size (at least the same size).

=== 102.2 Install a boot manager (LCN-5 CTL-5) ===
  * Providing alternative boot locations and backup boot options
  * Install and configure a boot loader such as GRUB Legacy
  * Perform basic configuration changes for GRUB 2
  * Interact with the boot loader
  * Terms: /boot/grub/menu.lst, grub.cfg and other variations, grub-install, MBR, superblock

=== 102.3 Manage shared libraries (LCN-5 CTL-2) ===
  * Identify shared libraries
  * Identify the typical locations of system libraries
  * Load shared libraries
  * Terms: ldd, ldconfig, /etc/ld.so.conf, LD_LIBRARY_PATH

=== 102.4 Use Debian package management (LCN-5 CTL-2) ===
  * Install, upgrade and uninstall Debian binary packages
  * Find packages containing specific files or libraries which may or may not be installed
  * Obtain package information like version, content, dependencies, package integrity and installation status (whether or not the package is installed)
  * Terms: /etc/apt/sources.list, dpkg, dpkg-reconfigure, apt-get, apt-cache, aptitude

=== 102.5 Use RPM and YUM package management (LCN-5 CTL-2) ===
  * Install, re-install, upgrade and remove packages using RPM and YUM
  * Obtain information on RPM packages such as version, status, dependencies, integrity and signatures
  * Determine what files a package provides, as well as find which package a specific file comes from
  * Terms: rpm, rpm2cpio, /etc/yum.conf, /etc/yum.repos.d/, yum, yumdownloader
==== 103 GNU / Unix Commands 43%   ====

=== 103.1 Work on the command line (LCN-6 CTL-1) ===
  * Use single shell commands and one line command sequences to perform basic tasks on the command line
  * Use and modify the shell environment including defining, referencing and exporting environment variables
  * Use and edit command history
  * Invoke commands inside and outside the defined path
  * Terms: ., bash, echo, env, exec, export, pwd, set, unset, man, uname, history

=== 103.2 Process text streams using filters (LCN-6 CTL-1) ===
  * Send text files and output streams through text utility filters to modify the output
  * Using standard UNIX commands found in the GNU textutils package
  * Terms: cat, cut, expand, fmt, head, od, join, nl, paste, pr, sed, sort, split, tail, tr, unexpand, uniq, wc

=== 103.3 Perform basic file management (LCN-6 CTL-4) ===
  * Copy, move and remove files and directories individually
  * Copy multiple files and directories recursively
  * Remove files and directories recursively
  * Use simple and advanced wildcard specifications in commands
  * Using find to locate and act on files based on type, size, or time
  * Usage of tar, cpio, and dd
  * Terms: cp, find, mkdir, mv, ls, rm, rmdir, touch, tar, cpio, dd, file, gzip, gunzip, bzip2, file globbing

=== 103.4 Use streams, pipes and redirects (LCN-6 CTL-1) ===
  * Redirecting standard input, standard output and standard error
  * Pipe the output of one command to the input of another command
  * Use the output of one command as arguments to another command
  * Send output to both stdout and a file
  * Terms: tee, xargs

=== 103.5 Create, monitor and kill processes (LCN-6 CTL-2) ===
  * Run jobs in the foreground and background
  * Signal a program to continue running after logout
  * Monitor active processes
  * Select and sort processes for display
  * Send signals to processes
  * Terms: &, bg, fg, jobs, kill, nohup, ps, top, free, uptime, killall

=== 103.6 Modify process execution priorities (LCN-6 CTL-2) ===
  * Know the default priority of a job that is created
  * Run a program with higher or lower priority than the default
  * Change the priority of a running process
  * Terms: nice, ps, renice, top

=== 103.7 Search text files using regular expressions (LCN-6 CTL-1) ===
  * Create simple regular expressions containing several notational elements
  * Use regular expression tools to perform searches through a filesystem or file content
  * The following is a partial list of the used files, terms and utilities: grep, egrep, fgrep, sed, regex(7)

=== 103.8 Perform basic file editing operations using vi (LCN-6 CTL-5) ===
  * Navigate a document using vi
  * Use basic vi modes
  * Insert, edit, delete, copy and find text
  * Terms: vi, /, ?, h, j, k, l, i, o, a, c, d, p, y, dd, yy, ZZ, :w!, :q!, :e!

====  104 Devices, Filesystems, Filesystem Hierarchy 25% ====

=== 104.1 Create partitions and filesystems (LCN-7 CTL-3) ===
  * Use various mkfs commands to set up partitions and create various filesystems such as: ext2, ext3, xfs, reiserfs v3, vfat
  * Terms: fdisk, mkfs, mkswap

=== 104.2 Maintain the integrity of filesystems (LCN-7 CTL-3) ===
  * Verify the integrity of filesystems
  * Monitor free space and inodes
  * Repair simple filesystem problems
  * Terms: du, df, fsck, e2fsck, mke2fs, debugfs, dumpe2fs, tune2fs, xfs tools (such as xfs_metadump and xfs_info)

=== 104.3 Control mounting and unmounting of filesystems (LCN-7 CTL-3) ===
  * Manually mount and unmount filesystems
  * Configure filesystem mounting on bootup
  * Configure user mountable removeable filesystems
  * Terms: /etc/fstab, /media, mount, umount

=== 104.4 Manage disk quotas (LCN-7 CTL-4) ===
  * Set up a disk quota for a filesystem
  * Edit, check and generate user quota reports
  * Terms: quota, edquota, repquota, quotation

=== 104.5 Manage file permissions and ownership (LCN-7 CTL-4) ===
  * Manage access permissions on regular and special files as well as directories
  * Use access modes such as suid, sgid and the sticky bit to maintain security
  * Know how to change the file creation mask
  * Use the group field to grant file access to group members
  * Terms: chmod, umask, chown, chgrp

=== 104.6 Create and change hard and symbolic links (LCN-7 CTL-4) ===
  * Create links
  * Identify hard and/or soft links
  * Copying versus linking files
  * Use links to support system administration tasks
  * Terms: ln

=== 104.7 Find system files and place files in the correct location (LCN-7 CTL-4) ===
  * Understand the correct locations of files under the FHS
  * Find files and commands on a Linux system
  * Know the location and propose of important file and directories as defined in the FHS
  * Terms: find, locate, updatedb, whereis, which, type, /etc/updatedb.conf

===== LX0-102 =====

==== 105 Shells, Scripting and Data Management 17%  ====

=== 105.1 Customize and use the shell environment (LCN-13 CTL-9) ===
  * Set environment variables (e.g., PATH) at login or when spawning a new shell
  * Write BASH functions for frequently used sequences of commands
  * Maintain skeleton directories for new user accounts
  * Set command search path with the proper directory
  * Terms: /etc/profile, env, export, set, unset, ~/.bash_profile, ~/.bash_login, ~/.profile, ~/.bashrc, ~/.bash_logout, function, alias, lists

=== 105.2 Customize or write simple scripts (LCN-13 CTL-9) ===
  * Use standard sh syntax (loops, tests)
  * Use command substitution
  * Test return values for success or failure or other information provided by a command
  * Perform conditional mailing to the superuser
  * Correctly select the script interpreter through the shebang (#!) line
  * Manage the location, ownership, execution and suid-rights of scripts
  * Terms: for, while, test, if, read, seq

=== 105.3 SQL data management (LCN-13 CTL-9) ===
  * Use of basic SQL commands
  * Perform basic data manipulation
  * Terms: insert, update, select, delete, from, where, group by, order by, join

==== 106 User Interfaces and Desktops 8% ====

=== 106.1 Install and configure X11 (LCN-14 CTL-6) ===
  * Verify that the video card and monitor are supported by an X server
  * Awareness of the X font server
  * Basic understanding and knowledge of the X Window configuration file
  * Terms: /etc/X11/xorg.conf, xhost, DISPLAY, xwininfo, xdpyinfo, X

=== 106.2 Setup a display manager (LCN-14 CTL-6) ===
  * Turn the display manager on or off
  * Change the display manager greeting
  * Change default color depth for the display manager
  * Configure display managers for use by X-stations
  * Terms: /etc/inittab; plus xdm, kdm, and gdm configuration files

=== 106.3 Accessibility (LCN-14 CTL-6) ===
  * Keyboard Accessibility Settings (AccessX)
  * Visual Settings and Themes
  * Assistive Technology (ATs)
  * Terms: Sticky/Repeat Keys, Slow/Bounce/Toggle Keys, Mouse Keys, High Contrast/Large Print Desktop Themes, Screen Reader, Braille Display, Screen Magnifier, On-Screen Keyboard, Gestures (used at login, for example gdm), Orca, GOK, emacspeak

==== 107 Administrative Tasks 20% ====

=== 107.1 Manage user and group accounts and related system files (LCN-15 CTL-7) ===
  * Add, modify and remove users and groups
  * Manage user/group info in password/group databases
  * Create and manage special purpose and limited accounts
  * Terms: /etc/passwd, /etc/shadow, /etc/group, /etc/skel, chage, groupadd, groupdel, groupmod, passwd, useradd, userdel, usermod

=== 107.2 Automate system administration tasks by scheduling jobs (LCN-15 CTL-9) ===
  * Manage cron and at jobs
  * Configure user access to cron and at services
  * Terms: /etc/cron.{d,daily,hourly,monthly,weekly}, /etc/at.deny, /etc/at.allow, /etc/crontab, /etc/cron.allow, /etc/cron.deny, /var/spool/cron/*, crontab, at, atq, atrm

=== 107.3 Localization and internationalization (LCN-15 CTL-6) ===
  * Locale settings
  * Timezone settings
  * Terms: /etc/timezone, /etc/localtime, /usr/share/zoneinfo, environment variables (LC_*, LC_ALL, LANG, TZ), /usr/bin/locale, tzselect, tzconfig, date, iconv, UTF-8, ISO-8859, ASCII, Unicode

==== 108 Essential System Services 17% ====

=== 108.1 Maintain system time (LCN-16 CTL-7) ===
  * Set the system date and time
  * Set the hardware clock to the correct time in UTC
  * Configure the correct timezone
  * Basic NTP configuration
  * Knowledge of using the pool.ntp.org service
  * Terms: /usr/share/zoneinfo, /etc/timezone, /etc/localtime, /etc/ntp.conf, date, hwclock, ntpd, ntpdate, pool.ntp.org

=== 108.2 System logging (LCN-16 CTL-7) ===
  * Syslog configuration files
  * syslog standard facilities, priorities and actions
  * Terms: syslog.conf, syslogd, klogd, logger

=== 108.3 Mail Transfer Agent (MTA) basics (LCN-17 CTL-9) ===
  * Create e-mail aliases
  * Configure e-mail forwarding
  * Knowledge of commonly available MTA programs (postfix, sendmail, qmail, exim) (no configuration)
  * Terms: ~/.forward, sendmail emulation layer commands, newaliases, mail, mailq, postfix, sendmail, exim, qmail

=== 108.4 Manage printers and printing (LCN-18 CTL-6) ===
  * Basic CUPS configuration (for local and remote printers)
  * Manage user print queues
  * Troubleshoot general printing problems
  * Add and remove jobs from configured printer queues
  * Terms: CUPS configuration files, tools and utilities; /etc/cups; lpd legacy interface (lpr, lprm, lpq)

==== 109 Networking Fundamentals 23% ====

=== 109.1 Fundamentals of internet protocols (LCN-19 CTL-8) ===
  * Demonstrate an understanding network masks
  * Knowledge of the differences between private and public “dotted quad” IP-Addresses
  * Setting a default route
  * Knowledge about common TCP and UDP ports (20, 21, 22, 23, 25, 53, 80, 110, 119, 139, 143, 161, 443, 465, 993, 995)
  * Knowledge about the differences and major features of UDP, TCP and ICMP
  * Knowledge of the major differences between IPv4 and IPV6
  * Knowledge of the basic features of IPv6
  * Terms: /etc/services, ftp, telnet, host, ping, dig, traceroute, tracepath

=== 109.2 Basic network configuration (LCN-20 CTL-8) ===
  * Manually and automatically configure network interfaces
  * Basic TCP/IP host configuration
  * Terms: /etc/hostname, /etc/hosts, /etc/resolv.conf, /etc/nsswitch.conf, ifconfig, ifup, ifdown, route, ping

=== 109.3 Basic network troubleshooting (LCN-21 CTL-8) ===
  * Manually and automatically configure network interfaces and routing tables
  * Including adding, starting, stopping, restarting, deleting or reconfiguring network interfaces
  * Change, view or configure the routing table and correct an improperly set default route manually
  * Debug problems associated with the network configuration
  * Terms: ifconfig, ifup, ifdown, route, host, hostname, dig, netstat, ping, traceroute

=== 109.4 Configure client side DNS (LCN-20 CTL-8) ===
  * Demonstrate the use of DNS on the local system
  * Modify the order in which name resolution is done
  * Terms: /etc/hosts, /etc/resolv.conf, /etc/nsswitch.conf

==== 110 Security 15% ====

=== 110.1 Perform security administration tasks (LCN-22 CTL-10) ===
  * Audit a system to find files with the suid/sgid bit set
  * Set or change user passwords and password aging information
  * Being able to use nmap and netstat to discover open ports on a system
  * Set up limits on user logins, processes and memory usage
  * Basic sudo configuration and usage
  * Terms: find, passwd, lsof, nmap, chage, netstat, sudo, /etc/sudoers, su, usermod, ulimit

=== 110.2 Setup host security (LCN-23 CTL-10) ===
  * Awareness of shadow passwords and how they work
  * Turn off network services not in use
  * Understand the role of TCP wrappers
  * Terms: /etc/nologin, /etc/passwd, /etc/shadow, /etc/xinetd.d/*, /etc/xinetd.conf, /etc/inetd.d/*, /etc/inetd.conf, /etc/inittab, /etc/init.d/*, /etc/hosts.allow, /etc/hosts.deny

=== 110.3 Securing data with encryption (LCN-24 CTL-10) ===
  * Perform basic OpenSSH 2 client configuration and usage
  * Understand the role of OpenSSH 2 server host keys
  * Perform basic GnuPG configuration and usage
  * Understand SSH port tunnels (including X11 tunnels)
  * Terms: ssh, ssh-keygen, ssh-agent, ssh-add, ~/.ssh/id_rsa and id_rsa.pub, ~/.ssh/id_dsa and id_dsa.pub, /etc/ssh/ssh_host_rsa_key and ssh_host_rsa_key.pub, /etc/ssh/ssh_host_dsa_key and ssh_host_dsa_key.pub, ~/.ssh/authorized_keys, /etc/ssh_known_hosts, gpg, ~/.gnupg/*

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