Sysfs

sysfs is a virtual filesystem (virtual means it takes up no space on the hard disk). It exports information about devices and drivers and is also used for configuration. It's generated by the kernel and always mounted at.

Usage
Use to read the information. For example, to output the charging level of a battery:

sysfs can be used to set values at runtime. For example, the command can be used to enable system suspension:

To set values at boot time create a local.d script.