sysfs
also: sysfs filesystem
A virtual filesystem that exposes kernel objects and device information as files and directories in /sys, allowing userspace programs to view and modify hardware settings and kernel parameters.
sysfs is a pseudo-filesystem mounted at /sys that provides a structured, hierarchical interface to kernel data structures. Unlike procfs, which focuses on process information, sysfs is designed to expose kernel objects like devices, drivers, and subsystems as a tree of files and directories.
The filesystem is dynamically generated by the kernel and updated in real-time as hardware is added or removed. Each device, bus, and driver typically has a corresponding directory under /sys containing attributes as files. For example, /sys/class/net/eth0/ contains network device settings, and /sys/devices/ shows the complete device hierarchy.
Users and tools can read from sysfs files to inspect hardware properties (like cat /sys/class/net/eth0/speed to check network speed) or write to certain files to modify kernel behavior without recompiling. This makes sysfs essential for hardware management, udev rules, and system monitoring utilities.