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What is Sysfs (/sys)?

A virtual filesystem that exports information about kernel subsystems, hardware devices, and device drivers in a structured hierarchy.

Sysfs (/sys) provides a structured view of the device model and kernel objects. Unlike /proc which evolved organically, /sys was designed with a clean hierarchy: /sys/class/ groups devices by type (network, block, input), /sys/bus/ organizes by bus type (PCI, USB, SCSI), /sys/devices/ shows the physical device tree, and /sys/module/ lists loaded kernel modules with their parameters. Sysfs enables device management from userspace — for example, changing LED brightness by writing to /sys/class/leds/*/brightness. The udev device manager uses sysfs information to create device nodes in /dev dynamically.

Related Terms

Journald
The systemd journal daemon that collects and stores log data from services, the kernel, and boot messages in a structured binary format.
Journalctl
A command-line tool for querying and viewing logs collected by systemd's journal logging system.
Firewalld
A dynamic firewall management tool for Linux that provides a D-Bus interface for managing firewall rules with zones.
Rsync
A fast, versatile file synchronization tool that efficiently transfers and syncs files between local and remote systems.
Grep
A command-line utility for searching plain-text data for lines matching a regular expression pattern.
LVM (Logical Volume Manager)
A storage management framework that provides flexible disk management through abstract layers of physical and logical volumes.
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