User and Permission Management in Linux

 Introduction

Linux is a multi-user operating system, which means multiple people can use the same system at the same time. To maintain security, Linux uses a permission system to control who can read, write, or execute files.

Step 1: Check Current User (whoami)

The whoami command displays the current logged-in user.

whoami

➡️ Example output: oracle or root.

Step 2: Switch Users (su)

The su command lets you switch to another user account.

su - username

➡️ Replace username with the account you want to switch to.

Step 3: File Permissions (ls -l)

Use ls -l to check file permissions.

ls -l

➡️ Example output: -rw-r--r-- 1 user user 1234 Sep 18 file1.txt

r = read

w = write

x = execute

Step 4: Change Permissions (chmod)

The chmod command changes file permissions.

chmod 755 script.sh

➡️ This allows the owner to read/write/execute, and others to read/execute.

Step 5: Change Ownership (chown)

The chown command changes file ownership.

chown oracle:dba file1.txt

➡️ This makes oracle the owner and dba the group.

Conclusion

User and permission management is a key part of Linux security. In the next post, we will cover process management commands to monitor and control running applications.