Branch keshav

2026/day-01/learning-plan.md

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+HI Bhaiya/Team,
+
+- Working professional with ~5 years experience in middleware administration
+- Career objective: transition into a DevOps-focused role
+- Primary skill focus areas:
+  - docker
+  - Kubernetes (K8s)
+  - CI/CD pipelines
+  - Shell scripting
+- Available study time:
+  - Weekdays: ~1.5 hours/day
+  - Weekends: ~3 hours/day (excluding live class sessions)

2026/day-02/linux-architecture-notes.md

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+**Process States in Linux**
+
+Running (R)
+The process is currently executing on the CPU or is ready to run and waiting for CPU time.
+
+Sleeping (S / D)
+The process is waiting for an event or resource, such as disk I/O, network I/O, or the completion of another process via wait().
+
+Zombie (Z)
+The process has completed execution, but its parent process has not yet collected its exit status. The process entry remains in the process table until it is reaped by the parent.
+
+**Commonly Used Linux Commands**
+
+ls -ltr – List files in long format, sorted by modification time
+
+ps -ef – Display all running processes with full details
+
+top – Monitor real-time CPU and memory usage
+
+grep -i – Search text patterns case-insensitively
+
+cd / mkdir / mv – Basic directory navigation and file management commands

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

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+**File System Commands**
+------------------------
+
+ls – List files and directories in the current path
+
+mkdir – Create a new directory
+
+cd – Change the current directory
+
+cd - – Switch back to the previous directory
+
+cp – Copy files or directories within the system
+
+mv – Move or rename files and directories
+
+touch – Create an empty file
+
+vi – Edit files using the vi editor
+
+less – View file contents in a readable, paginated format
+
+** Process & System Monitoring**
+-------------------------------
+
+top – Display real-time CPU and memory usage
+
+htop – Enhanced, interactive process viewer (graphical)
+
+hostname – Display the system hostname
+
+** Networking & Connectivity**
+------------------------------
+ping – Check network reachability of a host
+
+netstat – Display network connections, routing tables, and ports
+
+ifconfig – Show network interface and IP address details
+
+nslookup – Perform DNS resolution to find IP addresses
+
+curl – Send HTTP requests and inspect server responses
+
+telnet – Test connectivity to a specific host and port
+
+**Remote Access & File Transfer**
+-------------------------------
+
+ssh – Connect securely to a remote server
+
+scp – Copy files securely between servers

2026/day-04/linux-practice.md

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+**Check running processes**
+--------'----------------
+
+ps -ef | head
+
+<img width="777" height="197" alt="Screenshot 2026-02-10 at 6 30 15 PM" src="https://github.com/user-attachments/assets/da3251fa-67a9-4c15-bfe5-035677df2764" />
+
+
+systemctl status ssh
+<img width="1660" height="502" alt="Screenshot 2026-02-10 at 6 32 01 PM" src="https://github.com/user-attachments/assets/8d9b8bcb-f257-4bce-8541-d92f51b7180e" />
+
+**Log Checks**
+--------------
+journalctl -u ssh --no-pager | tail -n 10
+
+tail -n 20 /var/log/syslog
+
+<img width="1411" height="398" alt="Screenshot 2026-02-10 at 6 34 20 PM" src="https://github.com/user-attachments/assets/3b724069-3854-450d-9029-d2c22c3d6737" />
+
+

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

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+As per the task :
+
+basic command:
+**command : uname -a**
+output  : Darwin keshavs-MacBook-Air.local 25.2.0 Darwin Kernel Version 25.2.0: Tue Nov 18 21:08:48 PST 2025; root:xnu-12377.61.12~1/RELEASE_ARM64_T8132 arm64
+
+**command : lsb_release -a**
+output: command not found ( as i'm using terminal mac os ) 
+
+so instead i used 
+
+**command : sw_vers**
+output :  ProductName:		macOS
+          ProductVersion:		26.2
+          BuildVersion:		25C56
+
+cpu/Memory :
+
+**command : top**
+output : Processes: 885 total, 2 running, 883 sleeping, 4168 threads            18:33:04
+Load Avg: 1.59, 1.60, 1.77  CPU usage: 4.36% user, 2.54% sys, 93.8% idle
+SharedLibs: 594M resident, 119M data, 86M linkedit.
+MemRegions: 0 total, 0B resident, 335M private, 1524M shared.
+PhysMem: 15G used (2538M wired, 3789M compressor), 361M unused.
+VM: 393T vsize, 5268M framework vsize, 0(0) swapins, 0(0) swapouts.
+Networks: packets: 17128676/16G in, 8939745/3521M out.
+Disks: 26763847/487G read, 16055854/200G written.
+
+PID    COMMAND      %CPU TIME     #TH    #WQ  #PORT MEM    PURG  CMPRS  PGRP
+89247  Google Chrom 10.2 03:11:58 21     1    280   116M   0B    38M    95446
+419    WindowServer 9.7  10:44:46 24     6    4286  731M-  80M+  196M   419
+
+**command :ps -0 89247**
+ output : PID TTY           TIME CMD
+89247 ??       192:10.34 /Applications/Google Chrome.app/Contents/Frameworks/Go
+
+
+

2026/day-06/file-io-practice.md

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+**File I/O Practice – Day 06**
+ File Creation
+touch notes.txt
+
+keshavsingh@dhcp-10-48-12-102 ~ % touch notes.txt
+
+ Writing to a File (Overwrite)
+echo "hello" > notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello" > notes.txt 
+
+**Appending to a File**
+echo "hello2" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello2" >> notes.txt
+
+Reading the File
+cat notes.txt
+
+keshavsingh@dhcp-10-48-12-102 ~ % cat notes.txt 
+hello3
+hello2
+hello3
+hello5
+hello6
+
+** Overwriting File Content Again**
+--------------------
+
+echo "hello3" > notes.txt
+
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello2" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello3" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello5" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello6" >> notes.txt
+
+**Appending Multiple Lines**
+echo "hello2" >> notes.txt
+echo "hello3" >> notes.txt
+echo "hello5" >> notes.txt
+echo "hello6" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello2" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello3" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello5" >> notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello6" >> notes.txt
+
+ **Reading Partial File Content**
+head -n 2 notes.txt
+
+keshavsingh@dhcp-10-48-12-102 ~ % head -n 2 notes.txt
+hello3
+hello2
+
+** Writing and Displaying Output Using tee**
+-----------------------------
+echo "hello" | tee notes.txt
+keshavsingh@dhcp-10-48-12-102 ~ % echo "hello" | tee notes.txt
+hello
+
+keshavsingh@dhcp-10-48-12-102 ~ % cat << heloo bsc | tee -a notes.txt
+hello bsc
+keshavsingh@dhcp-10-48-12-102 ~ % cat notes.txt 
+hello bsc
+keshavsingh@dhcp-10-48-12-102 ~ % 
+
+
+

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

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+/ (root) - The starting point of everything
+/home - User home directories
+/root - Root user's home directory
+/etc - Configuration files
+/var/log - Log files (very important for DevOps!)
+/tmp - Temporary files
+Additional Directories (Good to Know):
+
+/bin - Essential command binaries
+/usr/bin - User command binaries
+/opt - Optional/third-party applications
+
+
+-----------------
+ubuntu@ip-172-31-46-16:~/practive-day07$ systemctl is-enabled nginx
+enabled
+ubuntu@ip-172-31-46-16:~/practive-day07$ journalctl -u nginx
+Jan 31 04:53:06 ip-172-31-46-16 systemd[1]: Starting nginx.service - A high performance web server and a reverse proxy server...
+Jan 31 04:53:06 ip-172-31-46-16 systemd[1]: Started nginx.service - A high performance web server and a reverse proxy server.
+Jan 31 06:12:19 ip-172-31-46-16 systemd[1]: Stopping nginx.service - A high performance web server and a reverse proxy server...
+Jan 31 06:36:06 ip-172-31-46-16 systemd[1]: Stopping nginx.service - A high performance web server and a reverse proxy server...
+Jan 31 06:36:06 ip-172-31-46-16 systemd[1]: nginx.service: Deactivated successfully.
+Jan 31 06:36:06 ip-172-31-46-16 systemd[1]: Stopped nginx.service - A high performance web server and a reverse proxy server.
+-- Boot cf21a7b824094ab89b67f0c197f9f202 --
+Feb 03 12:17:53 ip-172-31-46-16 systemd[1]: Starting nginx.service - A high performance web server and a reverse proxy server...
+Feb 03 12:17:53 ip-172-31-46-16 systemd[1]: Started nginx.service - A high performance web server and a reverse proxy server.
+Feb 03 12:20:39 ip-172-31-46-16 systemd[1]: Stopping nginx.service - A high performance web server and a reverse proxy server...
+Feb 03 12:20:40 ip-172-31-46-16 systemd[1]: nginx.service: Deactivated successfully.
+Feb 03 12:20:40 ip-172-31-46-16 systemd[1]: Stopped nginx.service - A high performance web server and a reverse proxy server.
+-- Boot 48e6240148074712bfe205b9953afc68 --
+Feb 03 12:21:50 ip-172-31-46-16 systemd[1]: Starting nginx.service - A high performance web server and a reverse proxy server...
+Feb 03 12:21:50 ip-172-31-46-16 systemd[1]: Started nginx.service - A high performance web server and a reverse proxy server.
+Feb 03 12:38:06 ip-172-31-46-16 systemd[1]: Stopping nginx.service - A high performance web server and a reverse proxy server...
+Feb 03 12:38:06 ip-172-31-46-16 systemd[1]: nginx.service: Deactivated successfully.
+Feb 03 12:38:06 ip-172-31-46-16 systemd[1]: Stopped nginx.service - A high performance web server and a reverse proxy server.
+ubuntu@ip-172-31-46-16:~/practive-day07$ sudo systemctl status nginx
+○ nginx.service - A high performance web server and a reverse proxy server
+     Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; preset: enabled)
+     Active: inactive (dead) since Tue 2026-02-03 12:38:06 UTC; 1min 19s ago
+   Duration: 16min 16.219s
+       Docs: man:nginx(8)
+    Process: 1832 ExecStop=/sbin/start-stop-daemon --quiet --stop --retry QUIT/5 --pidfile /run/nginx.pid (code=exited, status=0/SUCCESS)
+   Main PID: 557 (code=exited, status=0/SUCCESS)
+        CPU: 31ms
+
+Feb 03 12:21:50 ip-172-31-46-16 systemd[1]: Starting nginx.service - A high performance web server and a reverse proxy server...
+Feb 03 12:21:50 ip-172-31-46-16 systemd[1]: Started nginx.service - A high performance web server and a reverse proxy server.
+Feb 03 12:38:06 ip-172-31-46-16 systemd[1]: Stopping nginx.service - A high performance web server and a reverse proxy server...
+Feb 03 12:38:06 ip-172-31-46-16 systemd[1]: nginx.service: Deactivated successfully.
+Feb 03 12:38:06 ip-172-31-46-16 systemd[1]: Stopped nginx.service - A high performance web server and a reverse proxy server.

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

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+<img width="908" height="426" alt="Screenshot 2026-02-03 at 6 12 59 PM" src="https://github.com/user-attachments/assets/f7ac1bee-9b88-4c58-bb20-1a8f977f34ca" />
+
+
+<img width="1374" height="419" alt="Screenshot 2026-02-03 at 6 23 57 PM" src="https://github.com/user-attachments/assets/60181010-5324-401a-b305-3de60562b01a" />

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

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+sudo useradd -m tokyo
+sudo passwd tokyo
+
+sudo useradd -m berlin
+sudo passwd berlin
+
+sudo useradd -m professor
+sudo passwd professor
+<img width="722" height="375" alt="Screenshot 2026-02-11 at 6 08 03 PM" src="https://github.com/user-attachments/assets/84edfb9f-18ae-4219-b064-97d3d3d08124" />
+<img width="792" height="346" alt="Screenshot 2026-02-11 at 6 08 50 PM" src="https://github.com/user-attachments/assets/d518434f-1bda-4615-9426-34b01a21671b" />
+
+
+sudo groupadd developers
+sudo groupadd admins
+
+<img width="731" height="131" alt="Screenshot 2026-02-11 at 6 09 49 PM" src="https://github.com/user-attachments/assets/9b5ae488-013d-427c-853f-7274797e9cf3" />
+
+groups tokyo
+groups berlin
+
+
+<img width="658" height="197" alt="Screenshot 2026-02-11 at 6 11 14 PM" src="https://github.com/user-attachments/assets/503090cd-7467-47ac-bb05-2d6cac698f3f" />

2026/day-10/day-10-file-permissions.md

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+ubuntu@ip-172-31-46-16:~/day-10-permission$ touch devops.txt
+ubuntu@ip-172-31-46-16:~/day-10-permission$ echo "These are my DevOps notes." > notes.txt
+ubuntu@ip-172-31-46-16:~/day-10-permission$ vim script.sh
+ubuntu@ip-172-31-46-16:~/day-10-permission$ ls -l
+total 8
+-rw-rw-r-- 1 ubuntu ubuntu  0 Feb 11 12:44 devops.txt
+-rw-rw-r-- 1 ubuntu ubuntu 27 Feb 11 12:44 notes.txt
+-rw-rw-r-- 1 ubuntu ubuntu 21 Feb 11 12:44 script.sh
+
+============================
+<img width="844" height="168" alt="Screenshot 2026-02-11 at 6 15 46 PM" src="https://github.com/user-attachments/assets/2514ad0d-d5f3-4967-8004-bc2035a96f4c" />
+=============================
+
+ubuntu@ip-172-31-46-16:~/day-10-permission$ cat notes.txt
+These are my DevOps notes.
+ubuntu@ip-172-31-46-16:~/day-10-permission$ vim -R script.sh
+ubuntu@ip-172-31-46-16:~/day-10-permission$ head -n 5 /etc/passwd
+root:x:0:0:root:/root:/bin/bash
+daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
+bin:x:2:2:bin:/bin:/usr/sbin/nologin
+sys:x:3:3:sys:/dev:/usr/sbin/nologin
+sync:x:4:65534:sync:/bin:/bin/sync
+ubuntu@ip-172-31-46-16:~/day-10-permission$ tail -n 5 /etc/passwd
+
+<img width="879" height="354" alt="Screenshot 2026-02-11 at 6 16 37 PM" src="https://github.com/user-attachments/assets/b12e3702-48b6-4ab6-8fa3-79dad4ca4e8f" />
+===============================
+
+ubuntu@ip-172-31-46-16:~/day-10-permission$ chmod +x script.sh
+ubuntu@ip-172-31-46-16:~/day-10-permission$ ls -l script.sh
+-rwxrwxr-x 1 ubuntu ubuntu 21 Feb 11 12:44 script.sh
+ubuntu@ip-172-31-46-16:~/day-10-permission$ ./script.sh
+Hello DevOps
+<img width="1253" height="229" alt="Screenshot 2026-02-11 at 6 17 52 PM" src="https://github.com/user-attachments/assets/eaac1d6a-a25b-4c46-acd0-87955b356f21" />

2026/day-11/day-11-file-ownership.md

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+keshavsingh@keshavs-MacBook-Air ~ % ls -l
+total 250008
+drwx------@   5 keshavsingh  staff        160 15 Sep 10:12 Applications
+drwx------+  22 keshavsingh  staff        704  6 Feb 12:16 Desktop
+drwx------+  15 keshavsingh  staff        480 11 Dec 08:05 Documents
+
+

2026/day-12/day-12.md

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+memory usage  df -h → check disk space  free -m → check RAM usage  systemctl status <service> → check service health  journalctl -xe → check detailed errors  These give quick system overview during production issue.  ================= 1️⃣ Which 3 commands save you most time right now?  systemctl status → Instant service visibility  df -h → Quick disk troubleshooting  ls -l → Understand permissions immediately

2026/day-13/day-13-lvm.md

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+Assign a storage/volume to a server
+attach that storage to your server then it will be visible
+
+now you can step ahead to mount it
+
+firstly create a physical volume using below command
+
+lsblk - to list the bulk devices
+then use
+
+pvcreate /dev/<nameof-thestorage-from-lsblk>
+
+now that pv is created now you to create a logical group.
+
+vgcreate <nameforyou-VG> /dev/<nameof-thestorage-from-lsblk>
+
+once it is created , you need to creat a LVM(logicam volume) using the VG
+
+lvcreate -n <LVM-NAME> -L 5G <nameforyou-VG>  - this command created a LVM and assign a disk to it
+
+once it is created you see it using lvm/lsblk/lvdisplay
+
+now that its done, extract the LVM 
+
+Mkfs.ext4 /dev/<nameforyou-VG>/<LVM-NAME> 
+
+now you can mount to a directory whichever you want using mount command
+
+mount /dev/<nameforyou-VG>/<LVM-NAME>  </directory>
+
+and boom done.
+<img width="697" height="674" alt="Screenshot 2026-02-06 at 4 18 07 PM" src="https://github.com/user-attachments/assets/f79fcee9-2b19-4a95-9e1a-64b51eca10d7" />