CompTIA Linux+/LPIC-1 Portable Command Guide

At the impressionable age of 14, William “Bo” Rothwell crossed paths with a TRS-80 Micro Computer System (affectionately known as a “Trash 80”). Soon thereafter, the adults responsible for Bo made the mistake of leaving him alone with the TRS-80. He immediately dismantled it and held his first computer class, showing his friends what made this “computer thing” work. Since this experience, Bo’s passion for understanding how computers work and sharing this knowledge with others has resulted in a rewarding career in IT training. His experience includes Linux, Unix, IT security, Devops, and programming languages such as Perl, Python, Tcl, and BASH. He is the founder and lead instructor of One Course Source, an IT training organization.     

Introduction xxvi
Part I: System Architecture
CHAPTER 1 Determine and Confi gure Hardware Settings 1
    /sys 1
        Key Files and Directories in /sys 1
    /proc 1
        Key Files and Directories in /proc 2
    /dev 2
        Key Files in /dev 2
    modprobe 3
        Key Options for the modprobe Command 3
    lsmod 3
        Output of the lsmod Command 3
    lspci 4
        Key Options for the lspci Command 4
    lsusb 5
        Key Options for the lsusb Command 5
CHAPTER 2 Boot the System 7
    The Boot Sequence 7
    Common Commands for the Boot Loader 8
    Options for the Kernel at Boot Time 8
    SysVinit 9
    Systemd 10
    Upstart 11
    Boot Events in the Log Files 11
    dmesg 12
CHAPTER 3 Change Runlevels / Boot Targets and Shut Down or Reboot System 13
    Set the Default Runlevel or Boot Target 13
    Change between Runlevels / Boot Targets, Including Single-User Mode 14
    Shut Down and Reboot from the Command Line 14
    Alert Users Before Switching Runlevels / Boot Targets or Other Major System Events 15
    Properly Terminate Processes 15
    /etc/inittab 16
    shutdown 16
    init 16
    /etc/init.d/ 16
    telinit 16
    systemd 16
    systemctl 16
    /etc/systemd/ 16
    /usr/lib/systemd/ 16
    wall 16
Part II: Linux Installation and Package Management
CHAPTER 4 Design Hard Disk Layout 19
    Allocate Filesystems and Swap Space to Separate Partitions or Disks 19
    Tailor the Design to the Intended Use of the System 19
    Ensure the /boot Partition Conforms to the Hardware Architecture Requirements for Booting 20
    Knowledge of Basic features of LVM 20
    / (root) Filesystem 22
    /var Filesystem 22
    /home Filesystem 23
    /boot Filesystem 23
    Swap Space 23
    Mount Points 23
    Partitions 23
CHAPTER 5 Install a Boot Manager 25
    Providing Alternative Boot Locations and Backup Boot Options 25
    Install and Configure a Boot Loader Such As GRUB Legacy 25
    Perform Basic Configuration Changes for GRUB 2 26
    Interact with the Boot Loader 26
    menu.lst, grub.cfg, and grub.conf 28
    grub-install 30
    grub-mkconfig 30
    MBR 31
CHAPTER 6 Manage Shared Libraries 33
    Identify Shared Libraries 33
    Identify the Typical Locations of System Libraries 33
    Load Shared Libraries 33
    ldd 34
    ldconfig 34
    /etc/ld.so.conf 35
    LD_LIBRARY_PATH 36
CHAPTER 7 Use Debian Package Management 37
    Install, Upgrade, and Uninstall Debian Binary Packages 37
    Find Packages Containing Specific Files or Libraries that May or May Not Be Installed 37
    Obtain Package Information Such As Version, Content, Dependencies, Package Integrity, and Installation Status (Whether or Not the Package Is Installed) 38
    /etc/apt/sources.list 38
    dpkg 39
    dpkg-reconfigure 39
    apt-get 40
    apt-cache 40
    aptitude 41
CHAPTER 8 Use RPM and YUM Package Management 43
    Install, Reinstall, Upgrade, and Remove Packages Using RPM and YUM 43
    Obtain Information on RPM Packages Such As Version, Status, Dependencies, Integrity, and Signatures 43
    Determine What Files a Package Provides, as Well as Find Which Package a Specific File Comes From 44
    rpm 44
    rpm2cpio 45
    /etc/yum.conf 46
    /etc/yum.repos.d/ 46
    yum 47
    yumdownloader 48
Part III: GNU and Unix Commands
CHAPTER 9 Work on the Command Line 49
    Use Single Shell Commands and One-Line Command Sequences to Perform Basic Tasks on the Command Line 49
    Use and Modify the Shell Environment, Including Defining, Referencing, and Exporting Environment Variables 50
    Use and Edit Command History 51
    Invoke Commands Inside and Outside the Defined Path 52
    bash 52
    echo 52
    env 53
    export 53
    pwd 54
    set 55
    unset 55
    man 55
    uname 57
    history 57
    .bash_history 58
CHAPTER 10 Process Text Streams Using Filters 59
    cat 59
    cut 60
    expand 60
    fmt 61
    head 62
    join 62
    less 62
    nl 63
    od 63
    paste 63
    pr 64
    sed 64
    sort 66
    split 67
    tail 67
    tr 68
    unexpand 69
    uniq 69
    wc 69
CHAPTER 11 Perform Basic File Management 71
    Copy, Move, and Remove Files and Directories Individually 71
    Copy Multiple Files and Directories Recursively 72
    Remove Files and Directories Recursively 72
    Use Simple and Advanced Wildcard Specifications in Commands 72
    Using find to Locate and Act on Files Based on Type, Size, or Time 72
    Usage of tar, cpio, and dd 72
    cp 72
    find 73
    mkdir 75
    mv 75
    ls 76
    rm 77
    rmdir 77
    touch 77
    tar 78
    cpio 78
    dd 79
    file 79
    gzip 79
    gunzip 80
    bzip2 80
    xz 81
    File Globbing 81
CHAPTER 12 Use Streams, Pipes, and Redirects 83
    Redirecting Standard Input, Standard Output, and Standard Error 83
    Pipe the Output of One Command to the Input of Another Command 84
    Use the Output of One Command as Arguments to Another Command 85
    Send Output to Both STDOUT and a File 86
    tee 86
    xargs 86
CHAPTER 13 Create, Monitor, and Kill Processes 89
    Run Jobs in the Foreground and Background 89
    Signal a Program to Continue Running After Logout 90
    Monitor Active Processes 90
    Select and Sort Processes for Display 90
    Send Signals to Processes 90
    & 90
    bg 90
    fg 91
    jobs 91
    kill 91
    nohup 92
    ps 92
    top 93
    free 94
    uptime 95
    pgrep 95
    pkill 95
    killall 96
CHAPTER 14 Modify Process Execution Priorities 97
    Know the Default Priority of a Job that Is Created 97
    Run a Program with Higher or Lower Priority than the Default 97
    Change the Priority of a Running Process 97
    nice 97
    ps 98
    renice 98
    top 98
CHAPTER 15 Search Text Files Using Regular Expressions 99
    Create Simple Regular Expressions Containing Several Notational Elements 99
    Use Regular Expression Tools to Perform Searches through a Filesystem or File Content 99
    grep 100
    egrep 101
    fgrep 101
    sed 101
    regex(7) 102
CHAPTER 16 Perform Basic File Editing Operations Using vi 105
    Navigate a Document Using vi 105
    Use Basic vi Modes 105
    Insert, Edit, Delete, Copy, and Find Text 106
    vi 106
    /, ? 106
    h, j, k, l 107
    i, o, a 107
    c, d, p, y, dd, yy 108
    ZZ, :w!, :q!, :e! 109
Part IV: Devices, Linux Filesystems, and the Filesystem Hierarchy Standard
CHAPTER 17 Create Partitions and Filesystems 111
    Manage MBR Partition Tables 111
    Use Various mkfs Commands to Create Various Filesystems, Such As ext2/ext3/ext4, XFS, and VFAT 112
    Awareness of ReiserFS and btrfs 112
    Basic Knowledge of gdisk and parted with GP 113
    fdisk 113
    gdisk 114
    parted 115
    mkfs 116
    mkswap 117
    swapon 117
CHAPTER 18 Maintain the Integrity of Filesystems 119
    Verify the Integrity of Filesystems 119
    Monitor Free Space and Inodes 119
    Repair Simple Filesystem Problems 119
    du 119
    df 120
    fsck 120
    e2fsck 121
    mke2fs 121
    debugfs 121
    dumpe2fs 122
    tune2fs 122
    XFS Tools (Such As xfs_metadump and xfs_info) 123
CHAPTER 19 Control Mounting and Unmounting of Filesystems 125
    Manually Mount and Unmount Filesystems 125
    Configure Filesystem Mounting on Bootup 125
    Configure User-Mountable Removable Filesystems 125
    /etc/fstab 125
    /media 126
    mount 126
    umount 127
CHAPTER 20 Manage Disk Quotas 129
    Set Up a Disk Quota for a Filesystem 129
    Edit, Check, and Generate User Quota Reports 130
    quota 130
    edquota 131
    repquota 132
    quotaon 132
CHAPTER 21 Manage File Permissions and Ownership 133
    Manage Access Permissions on Regular and Special Files As Well As Directories 133
    Use Access Modes Such As suid, sgid, and the Sticky Bit to Maintain Security 133
    Know How to Change the File Creation Mask 134
    Use the Group Field to Grant File Access to Group Members 134
    chmod 134
    umask 136
    chown 136
    chgrp 137
CHAPTER 22 Create and Change Hard and Symbolic Links 139
    Create Links 139
    Identify Hard and/or Soft Links 139
    Copying Versus Linking Files 139
        Hard Links 139
        Soft Links 140
    Use Links to Support System Administration Tasks 140
    ln 141
    ls 142
CHAPTER 23 Find System Files and Place Files in the Correct Location 143
    Understand the Correct Locations of Files Under the FHS 143
    Find Files and Commands on a Linux System 144
    Know the Location and Purpose of Important Files and Directories as Defined in the FHS 144
    find 144
    locate 146
    updatedb 147
    whereis 147
    which 147
    type 148
    /etc/updatedb.conf 148
Part V: Shell Scripting and Data Management
CHAPTER 24 Customize and Use the Shell Environment 151
    Set Environment Variables (For Example, PATH) at Login or When Spawning a New Shell 151
    Write Bash Functions for Frequently Used Sequences of Commands 153
    Maintain Skeleton Directories for New User Accounts 153
    Set Command Search Path with the Proper Directory 153
    source 154
    /etc/bash.bashrc 154
    /etc/profile 154
    env 154
    export 155
    set 155
    unset 155
    ~/.bash_profile 155
    ~/.bash_login 156
    ~/.profile 156
    ~/.bashrc 156
    ~/.bash_logout 156
    Function 156
    Alias 157
    Lists 157
CHAPTER 25 Customize or Write Simple Scripts 159
    Use Standard sh Syntax (Loops, Tests) 159
    Use Command Substitution 159
    Test Return Values for Success or Failure or Other Information Provided by a Command 160
    Perform Conditional Mailing to the Superuser 160
    Correctly Select the Script Interpreter through the Shebang (#!) Line 160
    Manage the Location, Ownership, Execution and suid-rights of scripts 161
    for 161
    while 161
    test 162
    if 163
    read 164
    seq 164
    exec 164
CHAPTER 26 SQL Data Management 165
    Use of Basic SQL Commands 165
    Perform Basic Data Manipulation 165
    insert 165
    update 166
    select 166
    delete 166
    from 166
    where 167
    group by 167
    order by 167
    join 167
Part VI: User Interfaces and Desktops
CHAPTER 27 Install and Confi gure X11 169
    Verify that the Video Card and Monitor Are Supported by an X Server 169
    Awareness of the X Font Server 169
    Basic Understanding and Knowledge of the X Window Configuration File 169
    /etc/X11/xorg.conf 169
    xhost 171
    DISPLAY 171
    xwininfo 172
    xdpyinfo 174
    X 174
CHAPTER 28 Set Up a Display Manager 175
    Basic Configuration of LightDM 175
    Turn the Display Manager On or Off 175
    Change the Display Manager Greeting 175
    Awareness of XDM, KDM, and GDM 176
    lightdm 176
    /etc/lightdm 176
CHAPTER 29 Accessibility 177
    Basic Knowledge of Keyboard Accessibility Settings (AccessX) 177
    Basic Knowledge of Visual Settings and Themes 177
    Basic Knowledge of Assistive Technology (AT) 178
    Sticky/Repeat Keys 178
    Slow/Bounce/Toggle Keys 179
    Mouse Keys 179
    High Contrast/Large Print Desktop Themes 179
    Screen Reader 180
    Braille Display 180
    Screen Magnifier 180
    On-Screen Keyboard 180
    Orca 180
    GOK 180
    emacspeak 180
Part VII: Administrative Tasks
CHAPTER 30 Manage User and Group Accounts and Related System Files 181
    Add, Modify, and Remove Users and Groups 181
    Manage User/Group Info in Password/Group Databases 181
    Create and Manage Special-Purpose and Limited Accounts 181
    /etc/passwd 182
    /etc/shadow 183
    /etc/group 184
    /etc/skel/ 184
    chage 184
    getent 185
    groupadd 185
    groupdel 185
    groupmod 185
    passwd 186
    useradd 186
    userdel 187
    usermod 187
CHAPTER 31 Automate System Administration Tasks by Scheduling Jobs 189
    Manage cron and at Jobs 189
    Configure User Access to cron and at Services 189
    Configure anacron 191
    /etc/cron.{d,daily,hourly,monthly,weekly}/ 191
    /etc/at.deny 192
    /etc/at.allow 192
    /etc/crontab 192
    /etc/cron.allow 193
    /etc/cron.deny 193
    /var/spool/cron/ 193
    crontab 193
    at 195
    atq 195
    atrm 195
    anacron 196
    /etc/anacrontab 196
CHAPTER 32 Localization and Internationalization 199
    Configure Locale Settings and Environment Variables 199
    Configure Timezone Settings and Environment Variables 199
    /etc/timezone 200
    /etc/localtime 200
    /usr/share/zoneinfo/ 200
    LC_* 201
    LC_ALL 202
    LANG 202
    TZ 202
    /usr/bin/locale 202
    tzselect 202
    timedatectl 205
    date 205
    iconv 206
    UTF-8 206
    ISO-8859 207
    ASCII 207
    Unicode 207
Part VIII: Essential System Services
CHAPTER 33 Maintain System Time 209
    Set the System Date and Time 209
    Set the Hardware Clock to the Correct Time in UTC 209
    Configure the Correct Timezone 209
    Basic NTP Configuration 209
    Knowledge of Using the pool.ntp.org Service 210
    Awareness of the ntpq Command 210
    /usr/share/zoneinfo/ 210
    /etc/timezone 210
    /etc/localtime 210
    /etc/ntp.conf 210
    date 211
    hwclock 211
    ntpd 211
    ntpdate 212
    pool.ntp.org 212
CHAPTER 34 System Logging 213
    Configuration of the Syslog Daemon 213
    Understanding of Standard Facilities, Priorities, and Actions 213
    Configuration of logrotate 213
    Awareness of rsyslog and syslog-ng 214
    syslog.conf 214
    syslogd 215
    klogd 216
    /var/log/ 216
    logger 216
    logrotate 216
    /etc/logrotate.conf 217
    /etc/logrotate.d/ 218
    journalctl 219
    /etc/systemd/journald.conf 219
    /var/log/journal/ 220
CHAPTER 35 Mail Transfer Agent (MTA) Basics 221
    Create Email Aliases 221
    Configure Email Forwarding 221
    Knowledge of Commonly Available MTA Programs (postfix, sendmail, qmail, exim) (no configuration) 221
    newaliases 222
    mail 222
    mailq 223
    postfix 223
    sendmail 223
    exim 223
    qmail 223
    ~/.forward 223
    sendmail Emulation Layer Commands 224
CHAPTER 36 Manage Printers and Printing 225
    Basic CUPS Configuration (for Local and Remote Printers) 225
    Manage User Print Queues 226
    Troubleshoot General Printing Problems 227
    Add and Remove Jobs from Configured Printer Queues 228
    CUPS Configuration files, Tools, and Utilities 228
    /etc/cups/ 228
    lpd Legacy Interface (lpr, lprm, lpq) 228
Part IX: Networking Fundamentals
CHAPTER 37 Fundamentals of Internet Protocols 229
    Demonstrate an Understanding of Network Masks and CIDR Notation 229
    Knowledge of the Differences Between Private and Public “Dotted Quad” IP Addresses 230
    Knowledge About Common TCP and UDP Ports and Services (20, 21, 22, 23, 25, 53, 80, 110, 123, 139, 143, 161, 162, 389, 443, 465, 514, 636, 993, 995) 231
    Knowledge About the Differences and Major Features of UDP, TCP, and ICMP 232
    Knowledge of the Major Differences Between IPv4 and IPv6 233
    Knowledge of the Basic Features of IPv6 233
    /etc/services 233
    IPv4, IPv6 234
    Subnetting 234
    TCP, UDP, ICMP 234
CHAPTER 38 Basic Network Confi guration 235
    Manually and Automatically Configure Network Interfaces 235
    Basic TCP/IP Host Configuration 235
    Setting a Default Route 235
    /etc/hostname 235
    /etc/hosts 236
    /etc/nsswitch.conf 236
    ifconfig 236
    ifup 237
    ifdown 238
    ip 238
    route 239
    ping 239
CHAPTER 39 Basic Network Troubleshooting 241
    Manually and Automatically Configure Network Interfaces and Routing Tables to Include Adding, Starting, Stopping, Restarting, Deleting, or Reconfiguring Network Interfaces 241
    Change, View, or Configure the Routing Table and Correct an Improperly Set Default Route Manually 241
    ifconfig 242
    ip 242
    ifup 242
    ifdown 242
    route 242
    host 242
    hostname 242
    dig 243
    netstat 244
    ping 244
    ping6 244
    traceroute 245
    traceroute6 245
    tracepath 246
    tracepath6 246
    netcat 246
CHAPTER 40 Confi gure Client-Side DNS 247
    Query Remote DNS Servers 247
    Configure local name resolution and use remote DNS servers 247
    Modify the Order in Which Name Resolution Is Done 247
    /etc/hosts 247
    /etc/resolv.conf 247
    /etc/nsswitch.conf 248
    host 248
    dig 248
    getent 248
Part X: Security
CHAPTER 41 Perform Security Administration Tasks 249
    Audit a System to Find Files with the suid/sgid Bit Set 249
    Set or Change User Passwords and Password-Aging Information 250
    Being Able to Use nmap and netstat to Discover Open Ports on a System 250
    Set Up Limits on User Logins, Processes, and Memory Usage 250
    Determine Which Users Have Logged in to the System or Are Currently Logged In 250
    Basic sudo Configuration and Usage 250
    find 250
    passwd 250
    fuser 250
    lsof 251
    nmap 252
    chage 253
    netstat 253
    sudo 253
    /etc/sudoers 253
    su 254
    usermod 254
    ulimit 255
    who, w, last 256
CHAPTER 42 Set Up Host Security 259
    Awareness of Shadow Passwords and How They Work 259
    Turn Off Network Services Not in Use 259
    Understand the Role of TCP Wrappers 260
    /etc/nologin 261
    /etc/passwd 261
    /etc/shadow 261
    /etc/xinetd.d/ 261
    /etc/xinetd.conf 262
    /etc/inetd.d/ 262
    /etc/inetd.conf 262
    /etc/inittab 263
    /etc/init.d/ 263
    /etc/hosts.allow 263
    /etc/hosts.deny 263
CHAPTER 43 Securing Data with Encryption 265
    Perform Basic OpenSSH 2 Client Configuration and Usage 265
    Understand the Role of OpenSSH 2 Server Host Keys 265
    Perform Basic GnuPG Configuration, Usage, and Revocation 265
    Understand SSH Port Tunnels (Including X11 Tunnels) 266
    ssh 266
    ssh-keygen 267
    ssh-agent 268
    ssh-add 268
    ~/.ssh/id_rsa and id_rsa.pub 268
    ~/.ssh/id_dsa and id_dsa.pub 268
    /etc/ssh/ssh_host_rsa_key and ssh_host_rsa_key.pub 269
    /etc/ssh/ssh_host_dsa_key and ssh_host_dsa_key.pub 269
    ~/.ssh/authorized_keys 269
    ssh_known_hosts 269
    gpg 270
    ~/.gnupg/ 271
APPENDIX Create Your Own Journal 273
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