Main

2026/day-01/learning-plan.md

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+# My current level
+I am not a complete fresher but also not intermediate.I have basic knowledge about linux commands, docker and ec2 instances.
+
+#Goals for next 90 days
+To learn python along with this devops course, Focus on building projects, Showing up everyday no matter how I feel.
+
+# Core devops skills I want to build
+Docker containerisation, Linux along with networking , Kubernetes.
+
+# Weekly time budget
+4-5 hours/day on weekdays  6-7 hours on weekends
+

2026/day-02/linux-architecture.md

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+# Core components of linux
+
+i) Hardware layer
+ii) Shell
+iii) Kernel
+iv) System libraries/USER/APLLICATIONS
+v) System utilities(like,GNU)
+
+# How processes are created in linux
+
+*fork() System Call: A running "parent" process initiates the fork() system call to create a new, nearly identical "child" process. 
+ The child process receives a copy of the parent's memory space, open file descriptors, and other resources
+*exec() System Call: After the fork(), the child process typically uses an exec() system call (e.g., execve()) to replace its entire memory space with a new program's code and data.
+*wait() System Call: The parent process often uses the wait() system call to pause its own execution until its child process finishes and exits,
+ allowing the parent to collect the child's exit status and prevent it from becoming a zombie process. 
+
+# Process states
+
+A process transitions through several states during its lifecycle: 
+
+1. Running (R): The process is either currently executing on the CPU or waiting in the run queue to be executed.
+2. Sleeping/Waiting (S or D): The process is waiting for some event to occur (e.g., I/O completion, a signal).
+3. Stopped (T): The process has been suspended by a job control signal (like Ctrl+Z).
+5. Zombie (Z): The process has terminated, but its parent process has not yet collected its exit status, so its entry still exists in the process table.
+
+# What systemd does
+
+1. Initializes the System: It is the first user-space process to run during boot (PID 1)
+2. Manages Services: It starts, stops, and restarts background services (daemons) efficiently using "unit files" which define how services should behave [2].
+3. Provides System Logging: It includes journald, a centralized logging management system [1].
+4. Manages Devices and Mount Points: It uses udev (as part of the suite) to manage device events and automatically handle device hot-plugging [1].
+5. Enables Parallelism: It uses socket and D-Bus activation to start services in parallel, significantly speeding up boot times [2].
+
+# Why does it matter
+
+1. Standardization: It provides a consistent, standardized framework across many different Linux distributions, making system administration and development more uniform [2].
+2. Faster Boot Times: Its design allows for aggressive parallelization during startup, which dramatically decreases the time it takes for a system to become usable [2].
+3. Modern Features: It offers robust features essential for modern computing, such as cgroup management for resource control, on-demand service activation, and better security isolation for services [1, 2].
+
+# List of 5 commands that I will be using daily
+
+1. cd
+2. ls
+3. pwd
+4. touch
+5. man
+
+

2026/day-03/linux-commands-cheatsheet.md

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+# Commands focused on process management
+
+1. ps aux (lists running processes with detailed info.)
+2. top (provides list of running processes)
+3. htop (advanced version of top where user can see horiontally and vertically)
+4. kill <PID> (sends a signal to terminate a process by its process id)
+5. pkill <name> (terminate a process by its name)
+
+# Use this command to see the linux distribution and version
+* cat /etc/os-release
+
+# Very improtant command to know the usage of a command
+* man <command> [type the command you want to get details of and it will give each and every detail about it]
+
+# Commands focused on file system
+
+1. ls (list directory contents)
+2. cd (change directory)
+3. pwd (print working directory)
+4. cp (copy files or directories)
+5. rm (remove file or directory
+6. head (display first few lines of a file)
+7. tail (display last few lines of a file)
+8. chmod (change file permissions i.e, rwx)
+9. chown (change file ownership)
+10. find (search for files ina directory hierarchy)
+11. tar (archive files)
+12. zip/unzip (compress and extract files) 
+
+# Commands focused on networking and troubleshooting
+
+1. curl (transfer data from or to a server)
+2. wget (download files from internet)
+3. ssh (secure shell to a remote server)
+4. ping (check connectivity to a host)

2026/day-04/linux-practise.md

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+# Outcome of ps
+ps
+    PID TTY          TIME CMD
+   1181 pts/1    00:00:00 sudo
+   1182 pts/1    00:00:00 su
+   1183 pts/1    00:00:00 bash
+   1688 pts/1    00:00:00 ps
+
+# Output of top
+1 root      20   0   22496  13704   9480 S   0.0   1.4   0:01.55
+      2 root      20   0       0      0      0 S   0.0   0.0   0:00.00
+      3 root      20   0       0      0      0 S   0.0   0.0   0:00.00
+      4 root       0 -20       0      0      0 I   0.0   0.0   0:00.00
+      5 root       0 -20       0      0      0 I   0.0   0.0   0:00.00
+      6 root       0 -20       0      0      0 I   0.0   0.0   0:00.00
+
+# Outcome of systemctl status
+systemctl status  1180
+● session-2.scope - Session 2 of User ubuntu
+     Loaded: loaded (/run/systemd/transient/session-2.scope; transient)
+  Transient: yes
+     Active: active (running) since Thu 2026-01-29 06:37:11 UTC; 36min ago
+      Tasks: 9
+     Memory: 93.7M (peak: 136.4M)
+        CPU: 5.584s
+     CGroup: /user.slice/user-1000.slice/session-2.scope
+             ├─ 875 "sshd: ubuntu [priv]"
+             ├─ 990 "sshd: ubuntu@pts/0"
+             ├─1027 -bash
+             ├─1180 sudo su
+             ├─1181 sudo su
+             ├─1182 su
+             ├─1183 bash
+             ├─1798 systemctl status 1180
+             └─1799 less
+
+# Outcome of tail
+tail -5 file
+ssh ..
+touch
+vi
+vim
+nano
+
+# Outcome of crontab -l
+crontab -l
+# Edit this file to introduce tasks to be run by cron.
+#
+# Each task to run has to be defined through a single line
+# indicating with different fields when the task will be run
+# and what command to run for the task
+#
+# To define the time you can provide concrete values for
+# minute (m), hour (h), day of month (dom), month (mon),
+# and day of week (dow) or use '*' in these fields (for 'any').
+#
+# Notice that tasks will be started based on the cron's system
+# daemon's notion of time and timezones.
+#
+# Output of the crontab jobs (including errors) is sent through
+# email to the user the crontab file belongs to (unless redirected).
+#
+# For example, you can run a backup of all your user accounts
+# at 5 a.m every week with:
+# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
+#
+# For more information see the manual pages of crontab(5) and cron(8)
+#
+# m h  dom mon dow   command
+
+0 3 * * *
+
+
+
+17 13 * * 4 echo "Weekend soon!" | mail -s "Reminder" gzeus5476@gmail.com
+
+# Outcome of journalctl
+journalctl -u google.com
+-- No entries --

2026/day-05/linux-troubleshooting-runbook.md

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+# uname -a
+Linux ip-172-31-21-199 6.14.0-1018-aws #18~24.04.1-Ubuntu SMP Mon Nov 24 19:46:27 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
+
+# cat /etc/os-release
+PRETTY_NAME="Ubuntu 24.04.3 LTS"
+NAME="Ubuntu"
+VERSION_ID="24.04"
+VERSION="24.04.3 LTS (Noble Numbat)"
+VERSION_CODENAME=noble
+ID=ubuntu
+ID_LIKE=debian
+HOME_URL="https://www.ubuntu.com/"
+SUPPORT_URL="https://help.ubuntu.com/"
+BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
+PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
+UBUNTU_CODENAME=noble
+LOGO=ubuntu-logo
+
+# lsb_release -a
+No LSB modules are available.
+Distributor ID: Ubuntu
+Description:    Ubuntu 24.04.3 LTS
+Release:        24.04
+Codename:       noble
+
+#  ps -o pid
+    PID
+   1322
+   1323
+   1324
+   1485
+
+# free -h
+               total        used        free      shared  buff/cache   a                                                                          vailable
+Mem:           957Mi       333Mi       397Mi       888Ki       383Mi                                                                                 623Mi
+Swap:             0B          0B          0B
+
+# df -h
+Filesystem      Size  Used Avail Use% Mounted on
+/dev/root        27G  2.2G   24G   9% /
+tmpfs           479M     0  479M   0% /dev/shm
+tmpfs           192M  872K  191M   1% /run
+tmpfs           5.0M     0  5.0M   0% /run/lock
+/dev/xvda16     881M   89M  730M  11% /boot
+/dev/xvda15     105M  6.2M   99M   6% /boot/efi
+tmpfs            96M   12K   96M   1% /run/user/1000
+
+#  du -sh
+8.0K    .
+
+# 
+ps aux
+USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
+root           1  0.0  1.3  22060 13348 ?        Ss   10:23   0:01 /sbin
+root           2  0.0  0.0      0     0 ?        S    10:23   0:00 [kthr
+
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2026/day-06/file-io-practise.md

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+# touch notes.txt
+# echo "HEllo sabhi ko" > notes.txt
+# echo "Hope you all are doing good" >> notes.txt
+# echo "Have a nice day" | tee -a notes.txt
+Have a nice day
+# head -n 2 notes.txt
+HEllo sabhi ko
+Hope you all are doing good
+# tail -n 2 notes.txt
+Hope you all are doing good
+Have a nice day
+

2026/day-07/day-07-linux-fs-and-scenarios.md

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+# du -sh /var/log 2>/dev/null | sort -n | tail -n 5
+132M    /var/log
+
+#  journalctl -u nginx | tail -n 1
+Feb 03 09:28:05 ip-172-31-21-199 systemd[1]: Started nginx.service - A high performance web server and a reverse proxy server.
+
+# cat /etc/hostname
+ip-172-31-21-199
+
+# systemctl is-enabled nginx
+enabled
+
+# systemctl list-unit-files | tail -3
+xfs_scrub_all.timer                            disabled        enabled
+
+410 unit files listed.
+
+#  ps aux --sort=-%cpu | head -3
+USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
+root           1  0.3  1.3  22092 13420 ?        Ss   :27   0:04 /sbin/init
+ubuntu      1335  0.2  0.7  14996  7140 ?        S    09:31   0:01 sshd: ubuntu@pts/0
+

2026/day-08/day-08-cloud-deployment.md

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+# LIST OF COMMANDS THAT I USED
+
+   1  ls
+    2  systemctl is-enabled nginx
+    3  sudo apt-get install nginx
+    4  systemctl is-enabled nginx
+    5  systemctl status nginx
+    6  cat /etc/hostname
+    7  scp -i downloads/nginx.pem ubuntu@54.87.49.42:~/nginx-logs.txt .
+    8  sudo scp -i downloads/nginx.pem ubuntu@54.87.49.42:~/nginx-logs.txt .
+    9  scp -i nginx.pem ubuntu@54.87.49.42:~/nginx-logs.txt . 
+   11  systemctl is-enabled nginx 
+   15  history
+    427  scp -i downloads/nginx.pem ubuntu@52.91.197.11:~/nginx-logs.txt .
+  428  chmod 600 downloads/nginx.pem
+  429  scp -i downloads/nginx.pem ubuntu@52.91.197.11:~/nginx-logs.txt .
+  430  ls -l downloads/nginx.pem
+  431  sudo chmod 600 downloads/nginx.pem
+  432  ls -l downloads/nginx.pem
+  433  sudo chmod 600 downloads/nginx.pem
+  434  ls -l downloads/nginx.pem
+  435  mv downloads/nginx.pem nginxx.pem
+  436  ls
+  437  ls nginx.pem
+  438  cat nginxx.pem
+  439  ls -l
+  440  sudo chmod 600 nginxx.pem
+  441  ls -l
+  442  cd ~
+  443  ls
+  444  mkdir -p ~/.ssh
+  445  ls
+  446  ls -l
+  447  ls -a
+  448  cp /mnt/c/Users/dell/downloads/nginx.pem ~/.ssh/nginx.pem
+  449  cp /mnt/c/Users/dell/Downloads/nginx.pem ~/.ssh/nginx.pem
+  450  cd /mnt/c/Users/dell
+  451  ls
+  452  cp /mnt/c/Users/dell/nginxx.pem ~/.ssh/nginx.pem
+  453  cd ~
+  454  ls
+  455  ls -l ~/.ssh/nginxx.pem
+  456  sudo ls -l ~/.ssh/nginxx.pem
+  457  cd .ssh
+  458  ls
+  459  cd ..
+  460  ls
+  461  ls -l ~/.ssh/nginx.pem
+  462  chmod 600 ~/.ssh/nginx.pem
+  463  ls -l ~/.ssh/nginx.pem
+  464  scp -i ~/.ssh/nginx.pem ubuntu@52.91.197.11:/var/log/nginx/access.log .
+  465  ls
+  466  cat access.log
+
+
+
+# PROBLEM THAT I FACED WAS THAT I WAS RUNNING THAT (scp) COMMAND FROM MY SSH INSTANCE RATHER THAN MY LOCAL MACHINE SO IT TOOK ME A LOT OF TIME BUT NOW IT'S CLEAR
+
+# WHAT I LEARNED
+I learned how to copy log files from another server.
+

2026/day-08/nginx-logs.txt

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+152.58.157.30 - - [03/Feb/2026:10:06:02 +0000] "GET / HTTP/1.1" 200 409 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"
+152.58.157.30 - - [03/Feb/2026:10:06:02 +0000] "GET /favicon.ico HTTP/1.1" 404 196 "http://54.87.49.42/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"
+27.147.191.231 - - [03/Feb/2026:10:10:01 +0000] "GET / HTTP/1.1" 200 615 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36"
+195.178.110.39 - - [03/Feb/2026:10:22:25 +0000] "\x16\x03\x01\x00\xEE\x01\x00\x00\xEA\x03\x03\x9B\xB64\xBC\xED\x1EA\x17\x94D.PChV_\x0B\xF1\x83\xEFR\xBA\xAB\x09Q{\xB4\xD0\xDA\xB3`S " 400 166 "-" "-"
+13.89.125.26 - - [05/Feb/2026:05:32:31 +0000] "GET / HTTP/1.1" 200 409 "-" "Mozilla/5.0 zgrab/0.x"
+185.16.39.146 - - [05/Feb/2026:05:32:55 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget"
+185.16.39.146 - - [05/Feb/2026:05:39:40 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget"
+152.58.156.224 - - [05/Feb/2026:05:40:01 +0000] "GET / HTTP/1.1" 200 409 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"
+152.58.156.224 - - [05/Feb/2026:05:40:01 +0000] "GET /favicon.ico HTTP/1.1" 404 196 "http://52.91.197.11/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"
+185.16.39.146 - - [05/Feb/2026:05:46:38 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget"
+202.40.178.238 - - [05/Feb/2026:05:50:11 +0000] "GET / HTTP/1.1" 200 615 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36"
+185.16.39.146 - - [05/Feb/2026:05:52:53 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget"
+185.16.39.146 - - [05/Feb/2026:06:02:26 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget"
+204.76.203.219 - - [05/Feb/2026:06:06:53 +0000] "GET / HTTP/1.1" 200 409 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 Edg/90.0.818.46"
+185.16.39.146 - - [05/Feb/2026:06:11:34 +0000] "GET / HTTP/1.1" 200 615 "-" "Wget"

2026/day-09/day-09-user-management.md

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+# Users created
+jessi, hank, nairobi, tokyo 
+
+# Groups created
+developers, admins, project-team
+
+# Group Assignments
+walt: walt developers
+jessi: jessi developers admins
+hank: hank admins
+nairobi: nairobi admins project-team
+tokyo: tokyo
+
+# Directories created
+/opt/dev-project
+/opt/dev-project
+jessi
+hank
+nairobi
+tokyo
+
+# commands used
+useradd, mkdir, chgrp, chmod, groupadd, man, groups 
+
+# WHAT I LEARNED
+I learned how to add groups and users while making their own directories
+Also how to assign users to different groups 
+And to get lst of users in a group