Linux Administration Practical Notes | B.Sc. (Information Technology) Semester 5 | Mumbai University | munotes

Contents

Module I 1

1. What Linux Is, and What "Red Hat Enterprise Linux" Means 1
2. The Architecture of a Linux System: Kernel, Shell and Utilities 4
3. Getting Red Hat Enterprise Linux, and What AlmaLinux and Rocky Are 7
4. Making the Virtual Machine, in VirtualBox and in VMware 10
5. Installing RHEL 8 with Anaconda, Screen by Screen 13
6. The First Boot: Subscription, Updates and the Initial Setup 16
7. The Graphical Environment: What Starts When You See a Login Screen 18
8. The Display Manager: GDM, the Greeter and Your Session 21
9. The Desktop Environment: GNOME, Wayland and X11 23
10. The Terminal, the Shell and the Prompt 25
11. The Linux Directory Structure and the Filesystem Hierarchy Standard 28
12. File Systems Mounted into the Tree: lsblk, df, and What Is Not on a Disk 31
13. Reading the Manual: man, apropos and --help 35
14. Basic System Commands: Who You Are, Where You Are, What This Machine Is 39
15. The Three Standard Streams, and Redirecting Them 42
16. Pipes: Joining Commands Together 45
17. cat, less, head and tail: Reading a File 48
18. cut, sort, uniq and wc: Taking a File Apart 51
19. grep: Finding the Lines That Matter 54
20. Basic Regular Expressions 57
21. Extended Regular Expressions, and grep -E 60
22. awk: Records, Fields and Actions 62
23. systemd: Units, and the Service You Will Use Most 65
24. systemd Targets, and What "multi-user" Means 69
25. Logging In and Switching Users: who, id, su and sudo 72
26. find and locate: Finding Files on a Server 76
27. Essential File Management: Paths, Names and the Working Directory 79
28. ls, and How to Read a Long Listing 82
29. The Inode: What a File Is, and What a Name Is 86
30. mkdir, touch, cp, mv and rm: The Four You Type Every Day 89
31. Hard Links and Symbolic Links 92
32. Archiving and Compressing Are Two Different Jobs 96
33. tar: Creating, Listing and Extracting an Archive 99
34. gzip, bzip2 and xz: Compressing 102
35. star: The Other Archiver MU Names 105
36. zip and unzip: The Archive Windows Can Open 108
37. Ownership: chown and chgrp 111
38. Basic Permissions: rwx for User, Group and Other 114
39. chmod: The Octal Form and the Symbolic Form 117
40. umask: The Permissions a New File Is Given 120
41. set-UID, set-GID and the Sticky Bit 123
42. A set-GID Directory for a Group to Share 127
43. Access Control Lists: getfacl and setfacl 130
44. Default ACLs, So New Files Inherit the Rights 135
45. User-Extended Attributes: setfattr and getfattr 140
46. File Attributes: chattr and lsattr 144
47. The Four Files Behind Every User Account 148
48. useradd, usermod and userdel 152
49. The Defaults a New Account Gets: login.defs, useradd -D and /etc/skel 156
50. Groups: Primary, Secondary, groupadd and groupmod 159
51. Passwords: passwd and /etc/shadow 163
52. Password Aging with chage 167
53. su: Becoming Another User 171
54. sudo, /etc/sudoers and the wheel Group 174
55. Permissions and Advanced Permissions on a Real Shared Directory 179
56. What a Package Is, and What a Repository Is 184
57. yum and dnf: The Same Tool Under Two Names 188
58. Asking Questions: yum search, info, provides and list 191
59. Installing, Updating and Removing Software 195
60. yum history, and Undoing a Transaction 199
61. Package Groups and Application Streams 203
62. Repository Files in /etc/yum.repos.d 207
63. rpm: Querying the Package Database 211
64. rpm: Installing, Verifying, and Its Limits 214
65. A Repository on the Local File System, with createrepo 219

Module II Module 2

1. What a Process Is: PID, PPID, State and Owner 224
2. ps: Looking at What Is Running 228
3. Shell Jobs: Foreground, Background, and a Job That Outlives Your Login 232
4. Signals, kill and pkill 236
5. nice and renice: Deciding What Matters 240
6. top: Reading Every Field on the Screen 243
7. Finding the CPU-Hungry and Memory-Hungry Processes, and Killing Them 247
8. tuned: Profiles and tuned-adm 251
9. Disks, Devices and lsblk 255
10. MBR and GPT: Two Ways to Describe a Disk 258
11. fdisk: Partitioning an MBR Disk 261
12. gdisk and parted: Partitioning a GPT Disk 265
13. Deleting a Partition, and Making the Kernel Re-read the Table 269
14. Making a File System: ext4, xfs and vfat 273
15. Mounting and Unmounting: mount, umount and findmnt 277
16. /etc/fstab, and Mounting by UUID or Label 281
17. Swap: Adding It to a Running System 285
18. LVM: Physical Volumes, Volume Groups and Logical Volumes 289
19. Growing a Logical Volume and Its File System Without Unmounting 294
20. Addresses, Prefixes and Interfaces 299
21. ip: Reading the Configuration a Server Actually Has 303
22. Checking It Works: ping, ss and traceroute 307
23. NetworkManager: the Thing That Owns Your Configuration 311
24. nmcli: Devices and Connections 314
25. nmcli: Setting a Static IPv4 Address 318
26. IPv6, and Setting an IPv6 Address 321
27. nmtui: the Same Job on a Screen 324
28. Host Names: hostnamectl and /etc/hostname 327
29. Name Resolution: /etc/hosts, /etc/resolv.conf and getent 330
30. ssh: Logging in to Another Machine 333
31. The Host Key, known_hosts, and the Question Asked Once 337
32. scp and sftp: Copying Files over SSH 340
33. ssh-keygen and the authorized_keys File 344
34. A Passphrase, and ssh-agent So You Type It Once 348
35. sshd_config: Hardening the Server 352
36. Installing Apache and Starting It 356
37. Serving Your First Page, and Opening the Firewall for It 361
38. httpd.conf and conf.d: The Files and the Directives 364
39. DocumentRoot, Directory and the Permissions Apache Needs 368
40. A Name-Based Virtual Host 373
41. A Port-Based Virtual Host 377
42. What a Packet Filter Does: Tables, Chains and Rules 381
43. iptables: Listing, Adding and Deleting Rules 385
44. iptables: Saving Rules, and Where It Went in RHEL 9 and 10 389
45. firewalld: Zones, and What a Zone Is For 393
46. firewall-cmd: Services, Ports, Runtime and Permanent 397
47. Rich Rules, and Blocking One Address 400
48. SELinux: Why a Correct Configuration Still Fails 403
49. NFS: Exporting a Directory 407
50. NFS: Mounting the Export from a Client 411
51. CIFS: Mounting a Share, and a Credentials File 416
52. Remote File Systems in /etc/fstab, and _netdev 420
53. autofs: The Master Map and an Indirect Map 424
54. Mounting Home Directories on Demand 428
55. A First Script: The Shebang, the Permission and Running It 432
56. Variables, Quoting and Command Substitution 436
57. Arguments and the Exit Status 440
58. if and test: Making a Decision 444
59. for, while, case and Functions 448
60. A Script That Monitors a Server and Reports 452
61. Getting and Setting System Information from a Script 456
62. cron: The crontab and the Five Fields 460
63. The System Crontabs: /etc/crontab, cron.d and the Daily Directories 464
64. at: One Job, Once 468
65. Choosing Between at and cron, and What systemd Timers Add 472
66. Troubleshooting: journalctl, /var/log and a Method 475

Module J The journal and the practical examination

1. What Goes in the Journal, and the Shape of One Write-up 480
2. The Practical Examination: Two Hours, Thirty Marks 483
3. Questions Likely to Be Set on Module 1, Worked 486
4. Questions Likely to Be Set on Module 2, Worked 490
5. The Viva: What Is Asked, and How to Answer 495