# i3-nagbar > Display an error/warning in a bar on top of a screen. > More information: . - Display an error: `i3-nagbar {{[-m|--message]}} "{{error message}}"` - Display a warning: `i3-nagbar {{[-t|--type]}} warning {{[-m|--message]}} "{{warning message}}"` - Use the specified font: `i3-nagbar {{[-f|--font]}} "{{pango:monospace bold 9}}" {{[-m|--message]}} "{{error message}}"` - Create a button and run a command in a terminal on click: `i3-nagbar {{[-b|--button]}} "{{button text}}" {{command}} {{[-m|--message]}} "{{error message}}"` - Create a button and run a command on click: `i3-nagbar {{[-B|--button-no-terminal]}} "{{button text}}" {{command}} {{[-m|--message]}} "{{error message}}"` - Always open `i3-nagbar` on the primary monitor (default: focused monitor): `i3-nagbar {{[-pm|--primary --message]}} "{{error message}}"`