xref: /freebsd/sbin/devd/devd.conf.5 (revision 1fc7922f9f905b62ef9a6c03be498c282e7b382e)

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.\" Copyright (c) 2002 M. Warner Losh <imp@FreeBSD.org>
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.\" The section on comments was taken from named.conf.5, which has the
.\" following copyright:
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.Dd December 20, 2024
.Dt DEVD.CONF 5
.Os
.Sh NAME
.Nm devd.conf
.Nd configuration file format for
.Xr devd 8
.Sh DESCRIPTION
.Ss General Syntax
A
.Xr devd 8
configuration consists of two general features, statements
and comments.
All statements end with a semicolon.
Many statements can contain substatements, which are also
terminated with a semicolon.
.Pp
The following statements are supported:
.Bl -tag -width ".Ic options"
.It Ic attach
Specifies various matching criteria and actions to perform when
a newly attached device matches said criteria.
.It Ic detach
Specifies various matching criteria and actions to perform when
a newly detached device matches said criteria.
.It Ic nomatch
Specifies various matching criteria and actions to perform when
no device driver currently loaded in the kernel claims a (new)
device.
.It Ic notify
Specifies various matching criteria and actions to perform when the kernel
sends an event notification to userland.
.It Ic options
Specifies various options and parameters for the operation of
.Xr devd 8 .
.El
.Pp
Statements may occur in any order in the configuration file, and may be
repeated as often as required.
Further details on the syntax and meaning of each statement and their
substatements are explained below.
.Pp
Each statement, except
.Ic options
has a priority (an arbitrary number) associated with it, where
.Ql 0
is defined as the lowest priority.
If two statements match the same event, only the action of the statement with
highest priority will be executed.
In this way generic statements can be overridden for devices or
notifications that require special attention.
.Pp
The general syntax of a statement is:
.Bd -literal -offset indent
statement priority {
	substatement "value";
	...
	substatement "value";
};
.Ed
.Ss Sub-statements
The following sub-statements are supported within the
.Ic options
statement.
.Bl -tag -width ".Ic directory"
.It Ic directory Qq Ar /some/path ;
Adds the given directory to the list of directories from which
.Xr devd 8
will read all files named "*.conf" as further
configuration files.
Any number of
.Ic directory
statements can be used.
.It Ic pid-file Qq Pa /var/run/devd.pid ;
Specifies PID file.
.It Ic set Ar regexp-name Qq Ar (some|regexp) ;
Creates a regular expression and assigns it to the variable
.Ar regexp-name .
The variable is available throughout the rest of
the configuration file.
If the string begins with
.Ql \&! ,
it matches if the regular expression formed by the rest of the string
does not match.
All regular expressions have an implicit
.Ql ^$
around them.
.El
.Pp
The following sub-statements are supported within the
.Ic attach
and
.Ic detach
statements.
.Bl -tag -width ".Ic directory"
.It Ic action Qq Ar command ;
Command to execute upon a successful match.
Example
.Dq Li "/etc/pccard_ether $device-name start" .
.It Ic class Qq Ar string ;
This is shorthand for
.Dq Ic match Qo Li class Qc Qq Ar string .
.It Ic device-name Qq string ;
This is shorthand for
.Dq Ic match Qo Li device-name Qc Qq Ar string .
This matches a device named
.Ar string ,
which is allowed to be a regular expression or a variable previously created
containing a regular expression.
The
.Dq Li device-name
variable
is available for later use with the
.Ic action
statement.
.It Ic match Qo Ar variable Qc Qq Ar value ;
Matches the content of
.Ar value
against
.Ar variable ;
the content of
.Ar value
may be a regular expression.
Not required during
.Ic attach
nor
.Ic detach
events since the
.Ic device-name
statement takes care of all device matching.
For a partial list of variables, see below.
.It Ic media-type Qq Ar string ;
For network devices,
.Ic media-type
will match devices that have the given media type.
Valid media types are:
.Dq Li Ethernet ,
.Dq Li 802.11 ,
and
.Dq Li ATM .
.It Ic subdevice Qq Ar string ;
This is shorthand for
.Dq Ic match Qo Li subdevice Qc Qq Ar string .
.El
.Pp
The following sub-statements are supported within the
.Ic nomatch
statement.
.Bl -tag -width ".Ic directory"
.It Ic action Qq Ar command ;
Same as above.
.It Ic match Qo Ar variable Qc Qq Ar value ;
Matches the content of
.Ar value
against
.Ar variable ;
the content of
.Ar value
may be a regular expression.
For a partial list of variables, see below.
.El
.Pp
The following sub-statements are supported within the
.Ic notify
statement.
The
.Dq Li notify
variable is available inside this statement and contains, a value, depending
on which system and subsystem that delivered the event.
.Bl -tag -width ".Ic directory"
.It Ic action Qq Ar command ;
Command to execute upon a successful match.
Example
.Dq Li "/etc/rc.d/power_profile $notify" .
.It Ic match Qo Ar system | subsystem | type | notify Qc Qq Ar value ;
Any number of
.Ic match
statements can exist within a
.Ic notify
statement;
.Ar value
can be either a fixed string or a regular expression.
Below is a list of available systems, subsystems, and types.
.It Ic media-type Qq Ar string ;
See above.
.El
.Ss Variables that can be used with the match statement
A partial list of variables and their possible values that can be used together
with the
.Ic match
statement.
The variables are published by the bus based on characteristics of the device
that generated the event (for device events).
Variables for other classes of events are dependent on those events.
.Pp
.Bl -tag -width ".Li manufacturer" -compact
.It Ic Variable
.Ic Description
.It Li *
The entire message from the current event.
.It Li _
The entire message from the current event, after the initial type character.
.It Li timestamp
The time this event was processed, in seconds since 1970 dot fraction.
.It Li bus
Device name of parent bus.
.It Li cdev
Device node path if one is created by the
.Xr devfs 5
filesystem.
.It Li class
Device class.
.It Li comm
Executable name (kernel).
.It Li core
Path to core file (kernel).
.It Li device
Device ID.
.It Li devclass
Device Class (USB).
.It Li devsubclass
Device Sub-class (USB).
.It Li device-name
Name of attached/detached device.
.It Li endpoints
Endpoint count (USB).
.It Li function
Card functions.
.It Li interface
Interface ID (USB).
.It Li intclass
Interface Class (USB).
.It Li intprotocol
Interface Protocol (USB).
.It Li intsubclass
Interface Sub-class (USB).
.It Li jail
Jail name for the process triggering the rule (RCTL).
.It Li mode
Peripheral mode (USB).
.It Li notify
Match the value of the
.Dq Li notify
variable.
.It Li parent
Parent device.
.It Li pid
PID of the process triggering the rule (RCTL).
.It Li port
Hub port number (USB).
.It Li product
Product ID (USB).
.It Li release
Hardware revision (USB).
.It Li ruid
Real UID of the process triggering the rule (RCTL).
.It Li rule
Rule (RCTL).
.It Li sernum
Serial Number (USB).
.It Li slot
Card slot.
.It Li subvendor
Sub-vendor ID (PCI).
.It Li subdevice
Sub-device ID (PCI).
.It Li subsystem
Matches a subsystem of a system, see below.
.It Li system
Matches a system type, see below.
.It Li type
Type of notification, see below.
.It Li vendor
Vendor ID.
.El
.Ss Notify matching
A partial list of systems, subsystems, and types used within the
.Ic notify
mechanism.
.\"
.\" Please keep these tables sorted. Also, please use the same parameters
.\" for each of the tables so that things line up in columns nicely.
.\" Please do not omit the type column for notifiers that omit it.
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li ACPI Ta Ta Ta
Events related to the ACPI Subsystem.
.It Li ACPI Ta Li ACAD Ta Ta
AC line state ($notify=0x00 is offline, 0x01 is online).
.It Li ACPI Ta Li Button Ta Ta
Button state ($notify=0x00 is power, 0x01 is sleep).
.It Li ACPI Ta Li CMBAT Ta Ta
Battery events.
.It Li ACPI Ta Li Dock Ta Ta
Dock state ($notify=0x00 is undocked, 0x01 is docked).
.It Li ACPI Ta Li Lid Ta Ta
Lid state ($notify=0x00 is closed, 0x01 is open).
.It Li ACPI Ta Li PROCESSOR Ta Ta
Processor state/configuration ($notify=0x81 is a change in available Cx states).
.It Li ACPI Ta Li Resume Ta Ta
Resume notification.
.It Li ACPI Ta Li Suspend Ta Ta
Suspend notification.
.It Li ACPI Ta Li Thermal Ta Ta
Thermal zone events.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li AEON Ta Li power Ta Li press Ta
The power button on an Amiga has been pressed.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li CAM Ta Ta Ta
Events related to the
.Xr cam 4
system.
.It Li CAM Ta Li periph Ta Ta
Events related to peripheral devices.
.It Li CAM Ta Li periph Ta Li error Ta
Generic errors.
.It Li CAM Ta Li periph Ta Li timeout Ta
Command timeouts.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li CARP Ta Ta Ta
Events related to the
.Xr carp 4
protocol.
.It CARP Ta Ar vhid@inet Ta Ta
The
.Dq subsystem
contains the actual CARP vhid and the name of the network interface
on which the event took place.
.It CARP Ta Ar vhid@inet Ta MASTER Ta
Node become the master for a virtual host.
.It CARP Ta Ar vhid@inet Ta BACKUP Ta
Node become the backup for a virtual host.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li coretemp Ta Ta Ta
Events related to the
.Xr coretemp 4
device.
.It Li coretemp Ta Li Thermal Ta Ta
Notification that the CPU core has reached critical temperature.
.It Li coretemp Ta Li Thermal Ta Li temperature Ta
String containing the temperature of the core that has become too hot.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li DEVFS
.It Li DEVFS Ta Li CDEV Ta Li CREATE Ta
The
.Xr devfs 5
node is created.
.It Li DEVFS Ta Li CDEV Ta Li DESTROY Ta
The
.Xr devfs 5
node is destroyed.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li ETHERNET Ta Ar inet Ta IFATTACH Ta
Notification when the default VNET instance of the
.Em inet
interface is attached.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li GEOM Ta Ta Ta
Events related to the
.Xr geom 4
framework.
The difference compared to
.Li DEVFS
is that
.Li GEOM
only includes disk-like devices.
.It Li GEOM Ta Li DEV Ta Li CREATE Ta
A
.Xr geom 4
provider is created.
.It Li GEOM Ta Li DEV Ta Li DESTROY Ta
A
.Xr geom 4
provider is destroyed.
.It Li GEOM Ta Li DEV Ta Li GEOM::physpath Ta
The physical path of a device has changed.
.It Li GEOM Ta Li DEV Ta Li GEOM::rotation_rate Ta
The rotation rate of the disk has changed.
.It Li GEOM Ta Li DEV Ta Li MEDIACHANGE Ta
Physical media has changed.
.It Li GEOM Ta Li DEV Ta Li SIZECHANGE Ta
A
.Xr geom 4
provider size has changed.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li IFNET
.It Li IFNET Ta Em inet Ta Ta
The
.Dq subsystem
is the actual name of the network interface on which the event
took place.
.It Li IFNET Ta Em inet Ta Li LINK_UP Ta
Carrier status changed to UP.
.It Li IFNET Ta Em inet Ta Li LINK_DOWN Ta
Carrier status changed to DOWN.
.It Li IFNET Ta Em inet Ta Li ATTACH Ta
The network interface is attached to the system.
.It Li IFNET Ta Em inet Ta Li DETACH Ta
The network interface is detached from the system.
.It Li IFNET Ta Em inet Ta Li RENAME Ta
The network interface is renamed.
.It Li IFNET Ta Em inet Ta Li ADDR_ADD Ta
The network interface address added.
.It Li IFNET Ta Em inet Ta Li ADDR_DEL Ta
The network interface address removed.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li kernel Ta Li signal Ta Li coredump Ta
Notification that a process has crashed and dumped core.
.It Li kernel Ta Li power Ta Li resume Ta
Notification that the system has woken from the suspended state.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li nvme Ta Li controller Ta Li SMART_ERROR Ta
A SMART Critical Warning State change has happened.
$state has a hex bitmask of the bits that changed, as defined
in the NVMe Standard for Critical Warning field of log page 2
.Dq SMART / Health Information Log :
.Bl -column "Bit Value" "Meaning" -compact
.Sy "Bit Value" Ta Sy "Meaning"
.It 0x1 Ta Spare capacity below threshold
.It 0x2 Ta Temperature outside acceptable range
.It 0x4 Ta Reliability of media degraded
.It 0x8 Ta Media placed into read-only mode
.It 0x10 Ta Volatime memory backup failure
.It 0x20 Ta Persistent memrory read-only or degraded
.El
.It Li nvme Ta Li controller Ta Li RESET Ta
A controller reset event has happened.
$event is one of
.Dq start ,
.Dq success ,
and
.Dq timed_out
representing the start of a controller reset, the successful completion of a
controller reset, and a timeout while waiting for the controller to reset
respectively.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li PMU Ta Ta Ta
Notification of events from various types of Power Management Units.
.It Li PMU Ta Li "AC" Ta Ta
Notifications of AC power related events.
.It Li PMU Ta Li "AC" Ta Li overvoltage Ta
An over-voltage condition was detected on the AC power line.
.It Li PMU Ta Li "AC" Ta Li plugged Ta
Power has been applied to the AC power line.
.It Li PMU Ta Li "AC" Ta Li unplugged Ta
Power has been removed from the AC power line.
.It Li PMU Ta Li Battery Ta Ta
.It Li PMU Ta Li Battery Ta absent Ta
Battery is no longer absent.
.It Li PMU Ta Li Battery Ta charged Ta
The battery has become charged.
.It Li PMU Ta Li Battery Ta charging Ta
The battery has started charging.
.It Li PMU Ta Li Battery Ta disconnected Ta
The battery has been disconnected.
.It Li PMU Ta Li Battery Ta high-temp Ta
The battery reported a temperature over the limit.
.It Li PMU Ta Li Battery Ta low-temp Ta
The battery reported a temperature under the limit.
.It Li PMU Ta Li Battery Ta plugged Ta
The battery has become plugged (eg connected).
.It Li PMU Ta Li Battery Ta shutdown-threshold Ta
The power in the battery has fallen below the shutdown threshold.
.It Li PMU Ta Li Battery Ta warning-threshold Ta
The power in the battery has fallen below the warn the user threshold.
.It Li PMU Ta Li Button Ta pressed Ta
A button on a
.Xr adb 4
or
.Xr pmu 4
has been pressed.
.It Li PMU Ta Li keys Ta Ta
One of the keys on the
.Xr adb 4
keyboard has been pressed.
.It Li PMU Ta Li keys Ta brightness Ta
A brightness level change has been requested.
Direction is in the $notify variable.
.It Li PMU Ta Li keys Ta mute Ta
The mute key
.It Li PMU Ta Li keys Ta volume Ta
A volume level change has been requested.
Direction is in the $notify variable.
.It Li PMU Ta Li keys Ta eject Ta
An ejection has been requested.
.It Li PMU Ta Li lid Ta close Ta
The
.Xr pmc 4
device has detected the lid closing.
.It Li PMU Ta Li lid Ta open Ta
The
.Xr pmc 4
device has detected the lid openinging.
.It Li PMU Ta Li POWER Ta ACLINE Ta
The
.Xr pmc 4
device has detected an AC line state ($notify=0x00 is offline, 0x01 is online).
.It Li PMU Ta Li USB Ta overvoltage Ta
An over-voltage condition on the power lines for the USB power pins.
.It Li PMU Ta Li USB Ta plugged Ta
A device has been plugged into a USB device.
.It Li PMU Ta Li USB Ta undervoltage Ta
An under-voltage condition on the power lines for the USB power pins.
.It Li PMU Ta Li USB Ta unplugged Ta
A device has been unplugged into a USB device.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li RCTL Ta Ta Ta
Events related to the
.Xr rctl 8
framework.
.It Li RCTL Ta Li rule Ta Li matched Ta
A rule with action specified as "devctl" was triggered.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li USB Ta Ta Ta
Events related to the USB subsystem.
.It Li USB Ta Li DEVICE Ta Li ATTACH Ta
USB device is attached to the system.
.It Li USB Ta Li DEVICE Ta Li DETACH Ta
USB device is detached to the system.
.It Li USB Ta Li INTERFACE Ta Li ATTACH Ta
USB interface is attached to a device.
.It Li USB Ta Li INTERFACE Ta Li DETACH Ta
USB interface is detached from a device.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li VFS Ta Ta Ta
Events from the vfs system.
.It Li VFS Ta Li FS Ta Ta
Events that change what is mounted to the system.
.It Li VFS Ta Li FS Ta Li MOUNT Ta
Notification of a filesystem is mounted for the first time.
.It Li VFS Ta Li FS Ta Li REMOUNT Ta
Notification of a filesystem is remounted (whether or not the options actually change).
.It Li VFS Ta Li FS Ta Li UNMOUNT Ta
Notification of a filesystem being unmounted.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li VT Ta BELL Ta RING Ta
Notification that the console bell has rung.
See
.Xr vt 4
for details.
.El
.Pp
.Bl -column "System" "Subsystem" "1234567" -compact
.Sy "System" Ta Sy "Subsystem" Ta Sy "Type" Ta Sy "Description"
.It Li ZFS Ta ZFS Ta Ta
Events about the ZFS subsystem.
See
.Xr zfsd 8
and
.Pa /etc/devd/zfs.conf
for details.
.El
.Pp
.\"
.\" End of tables
.\"
A link state change to UP on the interface
.Dq Li fxp0
would result in the following notify event:
.Bd -literal -offset indent
system=IFNET subsystem=fxp0 type=LINK_UP
.Ed
.Pp
An AC line state change to
.Dq offline
would result in the following event:
.Bd -literal -offset indent
system=ACPI subsystem=ACAD notify=0x00
.Ed
.Ss Comments
Comments may appear anywhere that whitespace may appear in a
configuration file.
To appeal to programmers of all kinds, they can
be written in C, C++, or shell/Perl constructs.
.Pp
C-style comments start with the two characters
.Ql /*
(slash, star) and end with
.Ql */
(star, slash).
Because they are completely delimited with these characters,
they can be used to comment only a portion of a line or to span
multiple lines.
.Pp
C-style comments cannot be nested.
For example, the following is
not valid because the entire comment ends with the first
.Ql */ :
.Bd -literal -offset indent
/* This is the start of a comment.
   This is still part of the comment.
/* This is an incorrect attempt at nesting a comment. */
   This is no longer in any comment. */
.Ed
.Pp
C++-style comments start with the two characters
.Ql //
(slash, slash) and continue to the end of the physical line.
They cannot be continued across multiple physical lines; to have
one logical comment span multiple lines, each line must use the
.Ql //
pair.
For example:
.Bd -literal -offset indent
// This is the start of a comment.  The next line
// is a new comment, even though it is logically
// part of the previous comment.
.Ed
.Ss Notes on Variable Expansion
Variables are expanded by preceding them by a
.Dq $
sign.
Any text immediately following that sign, starting with a letter, a minus sign
.Dq - ,
an underscore
.Dq _ ,
or an asterisk
.Dq *
is considered an internal variable, and expanded accordingly.
If that variable does not exist, it silently expands to an empty string.
Consequently, if the intention is to pass a
.Xr sh 1
variable, it must be surrounded by braces to prevent it from being
considered an internal variable.
.Pp
See
.Sx EXAMPLES
for a detailed example.
.Pp
To prevent issues with special shell characters, the following happens for each
variable
.Ic $foo .
.Bl -enum
.It
The characters
.Dq $'
are inserted.
.It
The string
.Dq $foo
is removed.
.It
The value of the
.Ic foo
variable is inserted into the buffer with all single quote characters
prefixed by a backslash.
.It
A final
.Dq '
is inserted.
.El
.Pp
See
.Xr sh 1
for what this construct means.
It is safe in all context, except one: inside single quotes.
If foo=meta and bar=var, then a rule like the following:
.Bd -literal -offset indent -compact
action "echo '$foo $bar'";
.Ed
will be presented to the shell via
.Xr system 3
as
.Bd -literal -offset indent -compact
echo '$'meta' $'var''
.Ed
which produces the following output:
.Bd -literal -offset indent -compact
$meta $var
.Ed
as its output.
This is an unanticipated result.
A future version of this software will change this behavior.
Users are discouraged from using single quotes inside
.Ic action
value without due care.
.Pp
The above should be written as
.Bd -literal -offset indent -compact
action "echo $foo' '$bar"
.Ed
to produce a single argument to echo.
Given the above expansion, juxtaposing bare variables with
single quote expressions will produce the right output,
regardless of the value of the variable.
.Sh FILES
.Bl -tag -width ".Pa /etc/devd.conf" -compact
.It Pa /etc/devd.conf
The
.Xr devd 8
configuration file.
.It Pa /etc/devd
A directory that
.Nm devd
searches for additional configuration files.
.It Pa /usr/local/etc/devd
A directory that
.Nm devd
searches for additional configuration files.
.El
.Sh EXAMPLES
.Bd -literal
#
# This will catch link down events on the interfaces fxp0 and ath0
#
notify 0 {
	match "system"			"IFNET";
	match "subsystem"		"(fxp0|ath0)";
	match "type"			"LINK_DOWN";
	action "logger $subsystem is DOWN";
};

#
# Match lid open/close events
# These can be combined to a single event, by passing the
# value of $notify to the external script.
#
notify 0 {
	match "system"			"ACPI";
	match "subsystem"		"Lid";
	match "notify"			"0x00";
	action "logger Lid closed, we can sleep now!";
};

notify 0 {
	match "system"			"ACPI";
	match "subsystem"		"Lid";
	match "notify"			"0x01";
	action "logger Lid opened, the sleeper must awaken!";
};

#
# Match a USB device type
#
notify 0 {
	match "system"			"USB";
	match "subsystem"		"INTERFACE";
	match "type"			"ATTACH";
	match "intclass"		"0x0e";
	action "logger USB video device attached";
};

#
# Try to configure ath and iwn devices with pccard_ether
# as they are attached.
#
attach 0 {
        device-name "(ath|iwn)[0-9]+";
        action "/etc/pccard_ether $device-name start";
};

#
# Stop ath and iwn devices as they are detached from
# the system.
#
detach 0 {
        device-name "(ath|iwn)[0-9]+";
        action "/etc/pccard_ether $device-name stop";
};
.Ed
.Pp
The following example illustrates the difference betwen internal and shell variables:
.Bd -literal
attach 20 {
        device-name             "umodem[0-9]+";
        match "vendor"          "0x2047";
        match "product"         "0x001(0|3|4)";
        match "interface"       "0";
        action "cd /dev; p=$product; dn=$device-name; \\
                un=$(sysctl -n dev.umodem.${dn#umodem}.ttyname); \\
                chmod 666 cua${un}; ln -sf cua${un} mspfet${p#0x}";
};
.Ed
.Pp
.Dq product ,
and
.Dq device-name
are internal variables.
Their contents are initially assigned to shell variables
.Dq p ,
and
.Dq dn ,
respectively.
Then, variable
.Dq dn
is used inside a shell command substitution, assigning to shell variable
.Dq un .
Finally, this shell variable is used in two other shell statements, where
it needs to be wrapped in braces in order to prevent it from being
considered in internal variable to
.Nm devd .
.Pp
The installed
.Pa /etc/devd.conf
has many additional examples.
.Sh SEE ALSO
.Xr cam 4 ,
.Xr coretemp 4 ,
.Xr devfs 5 ,
.Xr re_format 7 ,
.Xr devd 8
.Sh BUGS
The variable expansion's interaction with single quotes is
suboptimal and surprising.