.SH NAME
udev \- Linux configurable dynamic device naming support
.SH SYNOPSIS
-.BI udev " hotplug-subsystem"
+.BI udev
.SH "DESCRIPTION"
.B udev
provides a dynamic device directory containing only the files for actually
.IR /etc/udev/rules.d/ .
.TP
.B udev_log
-The switch to enable/disable logging of udev information
+The logging priority which can be set to
+.IR "err " , "info "
+or the corresponding numerical
+.BR syslog (3)
+value.
The default value is
-.IR yes .
+.IR err .
.P
.RI "A sample " udev.conf " file might look like this:
.sp
.nf
-# udev_root - where to place the device nodes in the filesystem
-udev_root="/udev"
+# Where in the filesystem to place the device nodes
+udev_root="@udevdir@"
-# udev_db - The name and location of the udev database
-udev_db="/udev/.udevdb"
+# The name and location of the udev database.
+udev_db="@udevdir@/.udevdb"
-# udev_rules - The name of the udev rules file or directory to look
- for files with the suffix .rules
-udev_rules="/etc/udev/rules.d/"
+# The name and location of the udev rules file(s).
+udev_rules="@configdir@/rules.d"
-# udev_log - set to "yes" if you want logging, else "no"
-udev_log="yes"
+# The syslog(3) priority: "err", "info", or the numerical value.
+udev_log="err"
.fi
.P
The rules for device naming are read from the files located in the
.B last_rule
will be the last rule applied. No later rules will have any effect.
.sp
-.B OPTIONS
.B ignore_device
will ignore this device. No node will be created.
.sp
match an existing device node. Otherwise nothing is substituted. This
can be used to create compatibility symlinks and enumerate devices of
the same type originating from different kernel subsystems.
+.sp
+Note: The use of the enumeration facility is unreliable outside of
+udevstart where the node creation is serialized and predictable.
+The returned numbers rely on the order devices are probed on the
+system. If more than one device requests an enumeration for the same
+name at the same time, it may be possible that both requests receive the
+same name back from the database. The use of enumerations in todays setups
+where device can come and go at any time is not recomended.
.TP
.B %%
The '%' character itself.
# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
BUS=="usb", SYSFS{model}=="XV3", NAME=="video%n", SYMLINK="webcam%n"
-
-# grouping of optical drives from multiple kernel subsystems
-KERNEL=="sr*", NAME="%k", SYMLINK="cdrom%e"
-KERNEL=="scd*", NAME="%k", SYMLINK="cdrom%e"
-KERNEL=="pcd*", NAME="%k", SYMLINK="cdrom%e"
-KERNEL=="hd[a-z]", PROGRAM=="/bin/cat /proc/ide/%k/media", RESULT=="cdrom",
- NAME="%k", SYMLINK="cdrom%e"
.fi
.P
A number of different fields in the above configuration files support a simple
.br
In addition to the hotplug environment variables,
.B UDEV_LOG
-is set if udev is configured to use the syslog facility. Executed programs may
-want to follow that setting.
+is set and contains the numerical priority value, if udev is configured to use
+.BR syslog (3).
+Executed programs may want to follow that setting.
.B DEVNAME
is exported to make the name of the created node, or the name the network
device is renamed to, available to the executed program. The programs in every
.B udev
config file.
.TP
+.B UDEV_LOG
+Overrides the log priority specified in the config file.
+.TP
.B UDEV_NO_DEVD
The default behavior of
.B udev
.PP
.B Web resources:
.nf
-.I http://linux\-hotplug.sourceforge.net/
.I http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html
+.I http://linux\-hotplug.sourceforge.net/
.fi
.SH AUTHORS
.B udev
~ianmdlvl / elogind.git / blobdiff