# chmem > Modify the state of memory blocks (online or offline) in a Linux system. > Typically used in virtualized environments to manage memory hotplug. > More information: . - Set a memory block offline: `sudo chmem {{[-b|--block]}} {{[-d|--disable]}} {{block_number}}` - Set a memory block online: `sudo chmem {{[-b|--block]}} {{[-e|--enable]}} {{block_number}}` - Set a memory range offline using hexadecimal addresses: `sudo chmem {{[-d|--disable]}} 0x{{start_address}}-0x{{end_address}}` - Set a memory range online using hexadecimal addresses: `sudo chmem {{[-e|--enable]}} 0x{{start_address}}-0x{{end_address}}` - Set memory online and assign it to a specific zone (e.g., Movable): `sudo chmem {{[-e|--enable]}} 0x{{start_address}} {{[-z|--zone]}} {{Movable}}` - Display help: `chmem {{[-h|--help]}}`