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.TH SYSFS 5 2017-09-10 "Linux" "Linux Programmer's Manual"
.SH NAME
sysfs \- a filesystem for exporting kernel objects
.SH DESCRIPTION
The
.B sysfs
filesystem is a pseudo-filesystem which provides an interface to
kernel data structures.
(More precisely, the files and directories in
.B sysfs
provide a view of the
.IR kobject
structures defined internally within the kernel.)
The files under
.B sysfs
provide information about devices, kernel modules, filesystems,
and other kernel components.
.PP
The
.B sysfs
filesystem is commonly mounted at
.IR /sys .
Typically, it is mounted automatically by the system,
but it can also be mounted manually using a command such as:
.PP
.in +4n
.EX
mount \-t sysfs sysfs /sys
.EE
.in
.PP
Many of the files in the
.B sysfs
filesystem are read-only,
but some files are writable, allowing kernel variables to be changed.
.\"
.SS Files and directories
The following list describes some of the files and directories under the
.I /sys
hierarchy.
.TP
.IR /sys/block
.TP
.IR /sys/bus
.TP
.IR /sys/class
.TP
.IR /sys/dev
.TP
.IR /sys/devices
.TP
.IR /sys/firmware
.TP
.IR /sys/fs
.TP
.IR /sys/fs/cgroup
This directory conventionally is used as a mount point for a
.BR tmpfs (5)
filesystem containing mount points for
.BR cgroups (7)
filesystems.
.TP
.IR /sys/hypervisor
.TP
.IR /sys/kernel
.TP
.IR /sys/module
.TP
.IR /sys/power
.SH VERSIONS
The
.B sysfs
filesystem first appeared in Linux 2.6.0.
.SH CONFORMING TO
The
.B sysfs
filesystem is Linux-specific.
.SH NOTES
This manual page is incomplete, possibly inaccurate, and is the kind
of thing that needs to be updated very often.
.SH SEE ALSO
.BR proc (5),
.BR udev (7)
.PP
The kernel source file
.I Documentation/filesystems/sysfs.txt
and various other files in
.IR Documentation/ABI
and
.IR Documentation/*/sysfs.txt