How to Fix 'Permission Denied' Errors on Linux

Why You See "Permission Denied"

Linux enforces strict file permissions. Every file has an owner and a set of read/write/execute permissions for the owner, group, and everyone else. "Permission denied" means the user running the command doesn't have the rights needed for that action.

Step 1 — Check the Permissions

ls -la /path/to/file

-rw-r--r-- 1 root root 1234 Jun 1 config.txt

This file is owned by root and only root can write to it. The first group (rw-) is owner; second (r--) is group; third (r--) is everyone else.

Step 2 — Try sudo First

If you're trying to access a system file or run a privileged command, prefix with sudo:

sudo nano /etc/hosts
sudo cat /var/log/auth.log
sudo systemctl restart nginx

If sudo works, the file is owned by root and you just needed elevated privileges. Done.

Step 3 — Fix File Ownership with chown

If you own the project but someone ran a command as root and changed ownership:

# Check who owns it
ls -la /var/www/html/

# Change owner to the current user
sudo chown $USER:$USER /var/www/html/index.html

# Recursive: fix whole directory
sudo chown -R $USER:$USER /var/www/html/

Step 4 — Fix Permissions with chmod

# Add execute permission to a script you own
chmod +x deploy.sh

# Give your user write access to a file
chmod u+w config.txt

# Fix a web directory
chmod 755 /var/www/html
chmod 644 /var/www/html/index.html

Common Scenarios and Fixes

Script won't run: "Permission denied"

chmod +x script.sh
./script.sh

Can't write to /etc/ file

sudo nano /etc/nginx/nginx.conf

Web server can't read your files

sudo chown -R www-data:www-data /var/www/html/
sudo chmod -R 755 /var/www/html/

SSH key permissions are wrong

chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_ed25519
chmod 644 ~/.ssh/id_ed25519.pub
chmod 600 ~/.ssh/authorized_keys

Check Your Current User and Groups

whoami              # current user
id                  # user ID, group ID, and all groups
groups              # list all groups the current user belongs to

If you need to access something owned by a specific group, add yourself: sudo usermod -aG groupname $USER then log out and back in.