Day 10 – Linux User, Group & Session Management

🎯 On Day 10, I explored how Linux handles users, groups, permissions, and sessions—skills every DevOps engineer must master.

🧑‍💻 Commands I Practiced

👤 User Info & Session Checks

• View current user:

    whoami
  

Display all users & groups:

 cat /etc/passwd
 cat /etc/group

Find info about a specific user:

grep vagrant /etc/passwd
grep vagrant /etc/group
id <user>

➕ Add Users && Groups:

• Add user

 useradd <name>

• Add a group:

groupadd <name>

Add user to group:

 usermod -aG <group name> <user name>

🔐 Passwords & Login Set user passwords:

passwd <username>

Switched to a user:

 su - <user name>

🔍 Session & File Usage

Checked login history:

 last 
  who

• Installed and used lsof to see open files:

yum install lsof -y 
lsof -u vagrant

🧹 Deletion & Cleanup

• Deleted users (with home directories):

 userdel -r <user name>

Deleted group:

 groupdel <group name>

Verified home directory cleanup:

ls /home/

💡 Key Learnings

• ✅ Add users and groups securely

• ✅ Assign users to secondary groups

• ✅ Manage login credentials and switch users

• ✅ Monitor active sessions

• ✅ Clean up users and groups cleanly

📌 Next Steps

I’ll now dive into Linux File Permissions & Ownership