Import NetBSD sysctl(8)
Change-Id: Idc3a9138521de1329daaab3bd0907a0db0d37775
This commit is contained in:
David van Moolenbroek
527
sbin/sysctl/sysctl.8
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527
sbin/sysctl/sysctl.8
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@@ -0,0 +1,527 @@
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.\" $NetBSD: sysctl.8,v 1.162 2011/08/03 01:47:40 christos Exp $
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.\"
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.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
|
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.\" All rights reserved.
|
||||
.\"
|
||||
.\" Redistribution and use in source and binary forms, with or without
|
||||
.\" modification, are permitted provided that the following conditions
|
||||
.\" are met:
|
||||
.\" 1. Redistributions of source code must retain the above copyright
|
||||
.\" notice, this list of conditions and the following disclaimer.
|
||||
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||||
.\" notice, this list of conditions and the following disclaimer in the
|
||||
.\" documentation and/or other materials provided with the distribution.
|
||||
.\"
|
||||
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
||||
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
||||
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
||||
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
||||
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||||
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||||
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||||
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||||
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||||
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\"
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.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
|
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.\"
|
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.\" Redistribution and use in source and binary forms, with or without
|
||||
.\" modification, are permitted provided that the following conditions
|
||||
.\" are met:
|
||||
.\" 1. Redistributions of source code must retain the above copyright
|
||||
.\" notice, this list of conditions and the following disclaimer.
|
||||
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||||
.\" notice, this list of conditions and the following disclaimer in the
|
||||
.\" documentation and/or other materials provided with the distribution.
|
||||
.\" 3. Neither the name of the University nor the names of its contributors
|
||||
.\" may be used to endorse or promote products derived from this software
|
||||
.\" without specific prior written permission.
|
||||
.\"
|
||||
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
||||
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||||
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
||||
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||||
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||||
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||||
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||||
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||||
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)sysctl.8 8.1 (Berkeley) 6/6/93
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.\"
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.Dd August 2, 2011
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.Dt SYSCTL 8
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.Os
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.Sh NAME
|
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.Nm sysctl
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.Nd get or set kernel state
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.Sh SYNOPSIS
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.Nm sysctl
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.Op Fl AdeMnq
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.Oo
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.Fl r |
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.Fl x
|
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.Oc
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.Op Ar name ...
|
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.Nm sysctl
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.Op Fl nq
|
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.Oo
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.Fl r |
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.Fl x
|
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.Oc
|
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.Fl w
|
||||
.Ar name Ns Li [?]= Ns Ar value ...
|
||||
.Nm sysctl
|
||||
.Op Fl en
|
||||
.Oo
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||||
.Fl r |
|
||||
.Fl x
|
||||
.Oc
|
||||
.Fl a
|
||||
.Nm sysctl
|
||||
.Op Fl nq
|
||||
.Oo
|
||||
.Fl r |
|
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.Fl x
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.Oc
|
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.Fl f
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.Ar file
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.Sh DESCRIPTION
|
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The
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.Nm sysctl
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utility retrieves kernel state and allows processes with
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appropriate privilege to set kernel state.
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The state to be retrieved or set is described using a
|
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``Management Information Base'' (``MIB'') style name,
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||||
described as a dotted set of components.
|
||||
The
|
||||
.Sq /
|
||||
character may also be used as a separator and a leading separator
|
||||
character is accepted.
|
||||
If
|
||||
.Ar name
|
||||
specifies a non-leaf node in the MIB, all the nodes underneath
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||||
.Ar name
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||||
will be printed.
|
||||
.Pp
|
||||
The following options are available:
|
||||
.Bl -tag -width indent
|
||||
.It Fl A
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||||
List all the known MIB names including tables, unless any MIB
|
||||
arguments or
|
||||
.Fl f Ar file
|
||||
are given.
|
||||
Those with string or integer values will be printed as with the
|
||||
.Fl a
|
||||
flag; for table or structure values that
|
||||
.Nm
|
||||
is not able to print,
|
||||
the name of the utility to retrieve them is given.
|
||||
Errors in retrieving or setting values will be directed to stdout
|
||||
instead of stderr.
|
||||
.It Fl a
|
||||
List all the currently available string or integer values.
|
||||
The use of a solitary separator character (either
|
||||
.Sq \&.
|
||||
or
|
||||
.Sq / )
|
||||
by
|
||||
itself has the same effect.
|
||||
Any given
|
||||
.Ar name
|
||||
arguments are ignored if this option is specified.
|
||||
.It Fl d
|
||||
Descriptions of each of the nodes selected will be printed instead of
|
||||
their values.
|
||||
.It Fl e
|
||||
Separate the name and the value of the variable(s) with
|
||||
.Ql = .
|
||||
This is useful for producing output which can be fed back to the
|
||||
.Nm
|
||||
utility.
|
||||
This option is ignored if
|
||||
.Fl n
|
||||
is specified or a variable is being set.
|
||||
.It Fl f
|
||||
Specifies the name of a file to read and process.
|
||||
Blank lines and comments (beginning with
|
||||
.Ql # )
|
||||
are ignored.
|
||||
Line continuations with
|
||||
.Ql \e
|
||||
are permitted.
|
||||
Remaining lines are processed similarly to
|
||||
command line arguments of the form
|
||||
.Ar name
|
||||
or
|
||||
.Ar name Ns Li = Ns Ar value .
|
||||
The
|
||||
.Fl w
|
||||
flag is implied by
|
||||
.Fl f .
|
||||
Any
|
||||
.Ar name
|
||||
arguments are ignored.
|
||||
.It Fl M
|
||||
Makes
|
||||
.Nm
|
||||
print the MIB instead of any of the actual values contained in the
|
||||
MIB.
|
||||
This causes the entire MIB to be printed unless specific MIB arguments
|
||||
or
|
||||
.Fl f Ar file
|
||||
are also given.
|
||||
.It Fl n
|
||||
Specifies that the printing of the field name should be
|
||||
suppressed and that only its value should be output.
|
||||
This flag is useful for setting shell variables.
|
||||
For example, to save the pagesize in variable psize, use:
|
||||
.Bd -literal -offset indent -compact
|
||||
set psize=`sysctl -n hw.pagesize`
|
||||
.Ed
|
||||
.It Fl q
|
||||
Used to indicate that nothing should be printed for reads or writes unless an
|
||||
error is detected.
|
||||
For reads, not finding a variable does not print an error, but exits with
|
||||
an error code.
|
||||
This is useful just for testing that a variable exists.
|
||||
.It Fl r
|
||||
Raw output form.
|
||||
Values printed are in their raw binary forms as retrieved directly
|
||||
from the kernel.
|
||||
Some additional nodes that
|
||||
.Nm
|
||||
cannot print directly can be retrieved with this flag.
|
||||
This option conflicts with the
|
||||
.Fl x
|
||||
option.
|
||||
.It Fl w
|
||||
Sets the MIB style name given to the value given.
|
||||
The MIB style name and value must be separated by
|
||||
.Ql =
|
||||
with no whitespace.
|
||||
To prevent an error if the MIB style name does not exist (as would be the
|
||||
case with optional kernel components), one can separate the MIB style name
|
||||
and the value with
|
||||
.Ql ?= .
|
||||
Only integral and string values can be set via this method.
|
||||
.It Fl x
|
||||
Makes
|
||||
.Nm
|
||||
print the requested value in a hexadecimal representation instead of
|
||||
its regular form.
|
||||
If specified more than once, the output for each value resembles that of
|
||||
.Xr hexdump 1
|
||||
when given the
|
||||
.Fl C
|
||||
flag.
|
||||
This option conflicts with the
|
||||
.Fl r
|
||||
option.
|
||||
.Pp
|
||||
.El
|
||||
The
|
||||
.Ql proc
|
||||
top-level MIB has a special semantic: it represent per-process values
|
||||
and as such may differ from one process to another.
|
||||
The second-level name is the pid of the process (in decimal form),
|
||||
or the special word
|
||||
.Ql curproc .
|
||||
For variables below
|
||||
.Ql proc. Ns Ao pid Ac Ns .rlimit ,
|
||||
the integer value may be replaced
|
||||
with the string
|
||||
.Ql unlimited
|
||||
if it matches the magic value used to disable
|
||||
a limit.
|
||||
.Pp
|
||||
The information available from
|
||||
.Nm sysctl
|
||||
consists of integers, strings, and tables.
|
||||
The tabular information can only be retrieved by special
|
||||
purpose programs such as
|
||||
.Nm ps ,
|
||||
.Nm systat ,
|
||||
and
|
||||
.Nm netstat .
|
||||
See
|
||||
.Xr sysctl 7
|
||||
for description of available MIBs.
|
||||
.Sh CREATION AND DELETION
|
||||
New nodes are allowed to be created by the superuser when the kernel
|
||||
is running at security level 0.
|
||||
These new nodes may refer to existing kernel data or to new data that
|
||||
is only instrumented by
|
||||
.Xr sysctl 3
|
||||
itself.
|
||||
.Pp
|
||||
The syntax for creating new nodes is
|
||||
.Dq //create=new.node.path
|
||||
followed by one or more of the following attributes separated by
|
||||
commas.
|
||||
The use of a double separator (both
|
||||
.Sq /
|
||||
and
|
||||
.Sq \&.
|
||||
can be used as
|
||||
separators) as the prefix tells sysctl that the first series of tokens
|
||||
is not a MIB name, but a command.
|
||||
It is recommended that the double separator preceding the command not
|
||||
be the same as the separator used in naming the MIB entry so as to
|
||||
avoid possible parse conflicts.
|
||||
The
|
||||
.Dq value
|
||||
assigned, if one is given, must be last.
|
||||
.Pp
|
||||
.Bl -bullet -compact
|
||||
.It
|
||||
.Ar type= Ns Aq Ar T
|
||||
where
|
||||
.Ar T
|
||||
must be one of
|
||||
.Dq node ,
|
||||
.Dq int ,
|
||||
.Dq string ,
|
||||
.Dq quad ,
|
||||
or
|
||||
.Dq struct .
|
||||
If the type is omitted, the
|
||||
.Dq node
|
||||
type is assumed.
|
||||
.It
|
||||
.Ar size= Ns Aq Ar S
|
||||
here,
|
||||
.Ar S
|
||||
asserts the size of the new node.
|
||||
Nodes of type
|
||||
.Dq node
|
||||
should not have a size set.
|
||||
The size may be omitted for nodes of types
|
||||
.Dq int
|
||||
or
|
||||
.Dq quad .
|
||||
If the size is omitted for a node of type
|
||||
.Dq string ,
|
||||
the size will be determined by the length of the given value, or by
|
||||
the kernel for kernel strings.
|
||||
Nodes of type
|
||||
.Dq struct
|
||||
must have their size explicitly set.
|
||||
.It
|
||||
.Ar addr= Ns Aq Ar A
|
||||
or
|
||||
.Ar symbol= Ns Aq Ar A
|
||||
The kernel address of the data being instrumented.
|
||||
If
|
||||
.Dq symbol
|
||||
is used, the symbol must be globally visible to the in-kernel
|
||||
.Xr ksyms 4
|
||||
driver.
|
||||
.It
|
||||
.Ar n= Ns Aq Ar N
|
||||
The MIB number to be assigned to the new node.
|
||||
If no number is specified, the kernel will assign a value.
|
||||
.It
|
||||
.Ar flags= Ns Aq Ar F
|
||||
A concatenated string of single letters that govern the behavior of
|
||||
the node.
|
||||
Flags currently available are:
|
||||
.Bl -tag -width www
|
||||
.It a
|
||||
Allow anyone to write to the node, if it is writable.
|
||||
.It h
|
||||
.Dq Hidden .
|
||||
.Nm
|
||||
must be invoked with
|
||||
.Fl A
|
||||
or the hidden node must be specifically requested in order to see it
|
||||
.It i
|
||||
.Dq Immediate .
|
||||
Makes the node store data in itself, rather than allocating new space
|
||||
for it.
|
||||
This is the default for nodes of type
|
||||
.Dq int
|
||||
and
|
||||
.Dq quad .
|
||||
This is the opposite of owning data.
|
||||
.It o
|
||||
.Dq Own .
|
||||
When the node is created, separate space will be allocated to store
|
||||
the data to be instrumented.
|
||||
This is the default for nodes of type
|
||||
.Dq string
|
||||
and
|
||||
.Dq struct
|
||||
where it is not possible to guarantee sufficient space to store the
|
||||
data in the node itself.
|
||||
.It p
|
||||
.Dq Private .
|
||||
Nodes that are marked private, and children of nodes so marked, are
|
||||
only viewable by the superuser.
|
||||
Be aware that the immediate data that some nodes may store is not
|
||||
necessarily protected by this.
|
||||
.It x
|
||||
.Dq Hexadecimal .
|
||||
Make
|
||||
.Nm
|
||||
default to hexadecimal display of the retrieved value
|
||||
.It r
|
||||
.Dq Read-only .
|
||||
The data instrumented by the given node is read-only.
|
||||
Note that other mechanisms may still exist for changing the data.
|
||||
This is the default for nodes that instrument data.
|
||||
.It w
|
||||
.Dq Writable .
|
||||
The data instrumented by the given node is writable at any time.
|
||||
This is the default for nodes that can have children.
|
||||
.El
|
||||
.Pp
|
||||
.It
|
||||
.Ar value= Ns Aq Ar V
|
||||
An initial starting value for a new node that does not reference
|
||||
existing kernel data.
|
||||
Initial values can only be assigned for nodes of the
|
||||
.Dq int ,
|
||||
.Dq quad ,
|
||||
and
|
||||
.Dq string
|
||||
types.
|
||||
.El
|
||||
.Pp
|
||||
New nodes must fit the following set of criteria:
|
||||
.Pp
|
||||
.Bl -bullet -compact
|
||||
.It
|
||||
If the new node is to address an existing kernel object, only one of the
|
||||
.Dq symbol
|
||||
or
|
||||
.Dq addr
|
||||
arguments may be given.
|
||||
.It
|
||||
The size for a
|
||||
.Dq struct
|
||||
type node must be specified; no initial value is expected or permitted.
|
||||
.It
|
||||
Either the size or the initial value for a
|
||||
.Dq string
|
||||
node must be given.
|
||||
.It
|
||||
The node which will be the parent of the new node must be writable.
|
||||
.El
|
||||
.Pp
|
||||
If any of the given parameters describes an invalid configuration,
|
||||
.Nm
|
||||
will emit a diagnostic message to the standard error and exit.
|
||||
.Pp
|
||||
Descriptions can be added by the super-user to any node that does not
|
||||
have one, provided that the node is not marked with the
|
||||
.Dq PERMANENT
|
||||
flag.
|
||||
The syntax is similar to the syntax for creating new nodes with the
|
||||
exception of the keyword that follows the double separator at the
|
||||
start of the command:
|
||||
.Dq //describe=new.node.path=new node description .
|
||||
Once a description has been added, it cannot be changed or removed.
|
||||
.Pp
|
||||
When destroying nodes, only the path to the node is necessary, i.e.,
|
||||
.Dq //destroy=old.node.path .
|
||||
No other parameters are expected or permitted.
|
||||
Nodes being destroyed must have no children, and their parent must be
|
||||
writable.
|
||||
Nodes that are marked with the
|
||||
.Dq Dv PERMANENT
|
||||
flag (as assigned by the kernel) may not be deleted.
|
||||
.Pp
|
||||
In all cases, the initial
|
||||
.Sq =
|
||||
that follows the command (eg,
|
||||
.Dq create ,
|
||||
.Dq destroy ,
|
||||
or
|
||||
.Dq describe )
|
||||
may be replaced with another instance of the separator character,
|
||||
provided that the same separator character is used for the length of
|
||||
the name specification.
|
||||
.Sh FILES
|
||||
.Bl -tag -width /etc/sysctl.conf -compact
|
||||
.It Pa /etc/sysctl.conf
|
||||
.Nm
|
||||
variables set at boot time
|
||||
.El
|
||||
.Sh EXAMPLES
|
||||
For example, to retrieve the maximum number of processes allowed
|
||||
in the system, one would use the following request:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl kern.maxproc
|
||||
.Ed
|
||||
.Pp
|
||||
To set the maximum number of processes allowed
|
||||
in the system to 1000, one would use the following request:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl -w kern.maxproc=1000
|
||||
.Ed
|
||||
.Pp
|
||||
Information about the system clock rate may be obtained with:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl kern.clockrate
|
||||
.Ed
|
||||
.Pp
|
||||
Information about the load average history may be obtained with:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl vm.loadavg
|
||||
.Ed
|
||||
.Pp
|
||||
To view the values of the per-process variables of the current shell,
|
||||
the request:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl proc.$$
|
||||
.Ed
|
||||
can be used if the shell interpreter replaces $$ with its pid (this is true
|
||||
for most shells).
|
||||
.Pp
|
||||
To redirect core dumps to the
|
||||
.Pa /var/tmp/ Ns Aq username
|
||||
directory,
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl -w proc.$$.corename=/var/tmp/%u/%n.core
|
||||
.Ed
|
||||
should be used.
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl -w proc.curproc.corename=/var/tmp/%u/%n.core
|
||||
.Ed
|
||||
changes the value for the sysctl process itself, and will not have the desired
|
||||
effect.
|
||||
.Pp
|
||||
To create the root of a new sub-tree called
|
||||
.Dq local
|
||||
add some children to the new node, and some descriptions:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl -w //create=local
|
||||
sysctl -w //describe=local=my local sysctl tree
|
||||
sysctl -w //create=local.esm_debug,type=int,symbol=esm_debug,flags=w
|
||||
sysctl -w //describe=local.esm_debug=esm driver debug knob
|
||||
sysctl -w //create=local.audiodebug,type=int,symbol=audiodebug,flags=w
|
||||
sysctl -w //describe=local.audiodebug=generic audio debug knob
|
||||
.Ed
|
||||
Note that the children are made writable so that the two debug
|
||||
settings in question can be tuned arbitrarily.
|
||||
.Pp
|
||||
To destroy that same subtree:
|
||||
.Bd -literal -offset indent -compact
|
||||
sysctl -w //destroy=local.esm_debug
|
||||
sysctl -w //destroy=local.audiodebug
|
||||
sysctl -w //destroy=local
|
||||
.Ed
|
||||
.Sh SEE ALSO
|
||||
.Xr sysctl 3 ,
|
||||
.Xr ksyms 4 ,
|
||||
.Xr sysctl 7
|
||||
.Sh HISTORY
|
||||
.Nm sysctl
|
||||
first appeared in
|
||||
.Bx 4.4 .
|
||||
Reference in New Issue
Block a user