freebsd/share/man/man5/kernfs.5

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.\"	Mike Pritchard <mpp@FreeBSD.org>.  All rights reserved.
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.\" $FreeBSD$
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.Dd December 14, 1996
.Dt KERNFS 5
.Os BSD 4.4
.Sh NAME
.Nm kernfs
.Nd kernel file system
.Sh SYNOPSIS
.Bd -literal
kern		/kern	kernfs	rw 0 0
.Ed
.Sh DESCRIPTION
The kernel file system, or
.Nm kernfs ,
provides access to information on the currently running kernel.
It is normally mounted on
.Pa /kern .
The file system includes several regular files which can be
read, and some of which can also be written.
The contents of the files are in a machine-independent format,
either a string or an integer in decimal ASCII.  A trailing
newline character is added when a number is returned.
.Pp
The mount point contains the following files:
.Bl -tag -width copyright
.It Pa bootfile
The path from which the current kernel was booted.
.It Pa boottime
The time at which the system was last booted (decimal ASCII).
.It Pa copyright
The kernel copyright message.
.It Pa hostname
The current hostname, with a trailing newline.  The
current hostname can be changed by writing to this file.
A trailing newline will be stripped from the hostname being
written.
.It Pa hz
The frequency of the system clock (decimal ASCII).
.It Pa  loadavg
The 1, 5 and 15 minute load averages in kernel fixed-point
format.  The final integer is the fix-point scaling factor.
All numbers are in decimal ASCII.
.It Pa pagesize
The machine pagesize (decimal ASCII).
.It Pa physmem
The number of pages of physical memory in the machine (decimal ASCII).
.It Pa root
The system root directory.  In a chroot'ed environment,
.Xr mount_kernfs 8
can be used to create a new 
.Pa /kern
mount point.
.Pa /kern/root
will then refer to the system global root, not the current
process root.  Not currently enabled.
.It Pa rootdev
The root device.  Not currently enabled.
.It Pa rrootdev
The raw root device.  Not currently enabled.
.It Pa time
The second and microsecond values of the system clock (decimal ASCII).
.It Pa version
The kernel version string.  The head line for
.Pa /etc/motd
can be generated by running
.Dq Ic "sed 1q /kern/version"
.El
.Pp
Most of the information provided by the
.Nm
is also available from
.Xr sysctl 8 .
.Sh FILES
.Bl -tag -width /kern/XXXXXXX
.It Pa /kern
normal mount point for the
.Nm kernfs .
.El
.Sh SEE ALSO
.Xr sysctl 3 ,
.Xr mount_kernfs 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
first appeared in
.Bx 4.4 .
The
.Nm
manual page first appeared in
.Fx 2.2 .
.Sh AUTHORS
This manual page was written by
.An Mike Pritchard Aq mpp@FreeBSD.org ,
and was adapted from the
.Xr mount_kernfs 8
manual page written by
.An Jan-Simon Pendry .