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Useful Tips & Best Practices

Password Management​

# Locking user passwords
passwd -l username

# Unlocking
passwd -u username

# Check lock status
passwd -S username

File Ownership​

# Change ownership recursively
chown -R username:groupname /path/to/directory

# Change only group
chgrp -R groupname /path/to/directory

Finding Users and Groups​

# Find user UID
id username

# List all users
cat /etc/passwd

# List all groups
cat /etc/group

# Check group membership
groups username

SSH Key Setup for New User​

# Create SSH directory with proper permissions
mkdir -p /home/username/.ssh
chmod 700 /home/username/.ssh

# Add public key
echo "ssh-rsa AAAA..." >> /home/username/.ssh/authorized_keys
chmod 600 /home/username/.ssh/authorized_keys

# Fix ownership
chown -R username:username /home/username/.ssh