Common Mistakes I See Students Make

By Ravindra Bagale Last updated: 25 September 2026

Typing cd /Home or Index.html. Linux paths are case-sensitive.
Using chmod 777 to fix every error. It is insecure and usually hides a wrong owner or SELinux label.
usermod -G without -a. This replaces all the user's groups instead of adding one — the user may lose sudo access.
Running everything as root with sudo -i and then creating files that the normal user or web server cannot edit.
Using apt on Amazon Linux or yum on Ubuntu. First check cat /etc/os-release.
Getting stuck in vim. Remember: Esc then :q!.
rm -rf with a wrong path. There is no recycle bin — read the command twice before pressing Enter.