xlsatoms

Additional Notes

xlsatoms lists the interned atoms stored on the X server. An atom is a unique numeric identifier that maps to a string name. Atoms are used internally by X11 applications and toolkits to identify properties, selections, protocols, and other named entities efficiently.

Atoms are fundamental to X11 inter-client communication. For example, the WM_PROTOCOLS atom identifies the window manager protocols a client supports. xlsatoms is mainly useful for debugging and understanding X11 internals.

Syntax

xlsatoms [options]

Parameters

• options: Flags that change how xlsatoms behaves.
• target: Optional file, device, interface, user, service, or command target when the command supports one.

Common Options

• -display display: Specify the X display to query.
• -format string: Control the output format (%s for string, %d for number, %#x for hex).
• -name string: Display only the atom with the specified name.
• -range [low]-[high]: Display atoms in a numeric range.

Examples

xlsatoms

List all interned atoms on the X server.

xlsatoms -name WM_PROTOCOLS

Show the numeric ID for the WM_PROTOCOLS atom.

xlsatoms -range 300-350

Show atoms with IDs in the range 300 to 350.

xlsatoms -format "Atom %d = %s\n"

Custom output format.

Practical Notes

• Atom IDs vary between X server instances. The same string may have a different ID on different displays.
• Standard atoms are defined in the X Atom header files and the ICCCM specification.
• xprop is more commonly used to inspect window properties and their atoms.
• Atoms remain interned on the server until the X server resets.
• This tool is primarily useful for X11 application developers and debuggers.