User Management

Manage users, groups, and permissions.

User Operations

# Create user
useradd -m -s /bin/bash username
passwd username

# Delete user
userdel -r username

# Modify user
usermod -aG sudo username
usermod -s /bin/zsh username

Group Management

# Create group
groupadd developers

# Add user to group
usermod -aG developers username
gpasswd -a username developers

# Remove from group
gpasswd -d username developers

Sudo Configuration

# /etc/sudoers.d/developers
%developers ALL=(ALL) NOPASSWD: /usr/bin/docker
username ALL=(ALL) NOPASSWD: ALL

File Permissions

chmod 755 file        # rwxr-xr-x
chmod u+x file        # Add execute for user
chown user:group file # Change ownership
chown -R user:group dir/

# ACLs
setfacl -m u:user:rx file
getfacl file

Best Practices

• Use groups for access control
• Minimal sudo privileges
• Regular access reviews
• Strong password policies