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https://git.linuxfromscratch.org/lfs.git
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2c558d6914
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@7576 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
384 lines
13 KiB
XML
384 lines
13 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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<!ENTITY % general-entities SYSTEM "../general.ent">
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%general-entities;
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]>
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<sect1 id="ch-system-udev" role="wrap">
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<?dbhtml filename="udev.html"?>
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<title>Udev-&udev-version;</title>
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<indexterm zone="ch-system-udev">
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<primary sortas="a-Udev">Udev</primary>
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</indexterm>
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<sect2 role="package">
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<title/>
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<para>The Udev package contains programs for dynamic creation of device
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nodes.</para>
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<segmentedlist>
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<segtitle>&buildtime;</segtitle>
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<segtitle>&diskspace;</segtitle>
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<seglistitem>
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<seg>0.1 SBU</seg>
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<seg>4.8 MB</seg>
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</seglistitem>
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</segmentedlist>
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</sect2>
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<sect2 role="installation">
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<title>Installation of Udev</title>
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<para>The udev-config tarball contains LFS-specific files used to configure
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Udev.</para>
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<screen><userinput>tar xf ../&udev-config;.tar.bz2</userinput></screen>
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<para>Create some devices and directories that Udev cannot handle due to
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them being required very early in the boot process:</para>
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<screen><userinput>install -dv /lib/{firmware,udev/devices/{pts,shm}}
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mknod -m0666 /lib/udev/devices/null c 1 3
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ln -sv /proc/self/fd /lib/udev/devices/fd
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ln -sv /proc/self/fd/0 /lib/udev/devices/stdin
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ln -sv /proc/self/fd/1 /lib/udev/devices/stdout
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ln -sv /proc/self/fd/2 /lib/udev/devices/stderr
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ln -sv /proc/kcore /lib/udev/devices/core</userinput></screen>
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<para>Compile the package:</para>
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<screen><userinput>make EXTRAS="extras/ata_id extras/cdrom_id extras/edd_id \
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extras/firmware extras/floppy extras/path_id \
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extras/scsi_id extras/usb_id extras/volume_id"</userinput></screen>
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<variablelist>
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<title>The meaning of the make option:</title>
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<varlistentry>
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<term><parameter>EXTRAS=...</parameter></term>
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<listitem>
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<para>This builds several helper binaries that can aid in writing custom
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Udev rules.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>To test the results, issue:
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<userinput>make test</userinput>.</para>
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<para>Install the package:</para>
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<screen><userinput>make DESTDIR=/ \
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EXTRAS="extras/ata_id extras/cdrom_id extras/edd_id \
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extras/firmware extras/floppy extras/path_id \
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extras/scsi_id extras/usb_id extras/volume_id" install</userinput></screen>
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<variablelist>
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<title>The meaning of the make parameter:</title>
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<varlistentry>
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<term><parameter>DESTDIR=/</parameter></term>
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<listitem>
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<para>This prevents the Udev build process from killing any
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<command>udevd</command> processes that may be running on the
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host system.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Udev's configuration is far from ideal by default, so install
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the configuration files here:</para>
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<!-- FIXME: 90-bug.rules should be removed from the tarball once the book is released -->
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<screen><userinput>cp -v &udev-config;/[0-9]* /etc/udev/rules.d/</userinput></screen>
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<para>Now install a helper script that is not included in the main Udev
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tarball:</para>
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<screen><userinput>install -v -m 744 &udev-config;/write_cd_aliases /lib/udev/</userinput></screen>
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<para>Install the documentation that explains how to create Udev rules:</para>
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<screen><userinput>install -m644 -D -v docs/writing_udev_rules/index.html \
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/usr/share/doc/udev-&udev-version;/index.html</userinput></screen>
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<important>
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<para>When Udev is started by the LFS-Bootscripts, a replay of all kernel
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device events happens. These events tell Udev what devices exist.
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Sometimes the Udev bootscript doesn't wait long enough for
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<command>udevd</command> to process all of the replayed events and
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consequently the devices for those missed events are not created before the
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script exits. Since <command>udevd</command> is still running in the
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background, the devices will be created a few milliseconds later, but the
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next bootscript to run may require a device to exist before it has been
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created. To avoid such missed events, and to avoid hardcoding an overly
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long wait time, It is recommended that you run the following commands to
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aid the LFS development team in debugging these missed events and finding
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an acceptable solution more quickly.</para>
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<para>First, create a simple C file:</para>
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<screen><userinput>cat > bug.c << EOF
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<literal>/* Simple event recorder */
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#define _GNU_SOURCE
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <argz.h>
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int main(int argc, char * argv[])
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{
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char * envz;
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size_t len;
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int bug;
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bug = open("/dev/bug", O_WRONLY | O_APPEND);
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if (bug == -1)
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return 0;
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setenv("_SEPARATOR", "-------------------------------", 1);
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argz_create(environ, &envz, &len);
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argz_stringify(envz, len, '\n');
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envz[len-1]='\n';
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write(bug, envz, len);
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close(bug);
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free(envz);
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return 0;
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}</literal>
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EOF</userinput></screen>
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<para>Now compile it:</para>
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<screen><userinput>gcc -o /lib/udev/bug bug.c</userinput></screen>
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<para>When booting the new LFS system, if any events are missed, a warning
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message will appear and a <filename>/dev/bugreport</filename> file will be
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created. The warning message will tell you where to send feedback.</para>
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</important>
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</sect2>
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<sect2 id="contents-udev" role="content">
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<title>Contents of Udev</title>
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<segmentedlist>
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<segtitle>Installed programs</segtitle>
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<segtitle>Installed directory</segtitle>
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<seglistitem>
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<seg>ata_id, cdrom_id, create_floppy_devices, edd_id, firmware_helper,
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path_id, scsi_id, udevcontrol, udevd, udevinfo, udevmonitor, udevsettle,
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udevtest, udevtrigger, usb_id, vol_id, and write_cd_aliases</seg>
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<seg>/etc/udev</seg>
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</seglistitem>
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</segmentedlist>
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<variablelist>
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<bridgehead renderas="sect3">Short Descriptions</bridgehead>
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<?dbfo list-presentation="list"?>
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<?dbhtml list-presentation="table"?>
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<varlistentry id="ata_id">
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<term><command>ata_id</command></term>
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<listitem>
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<para>Provides Udev with a unique string and
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additional information (uuid, label) for an ATA drive</para>
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<indexterm zone="ch-system-udev ata_id">
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<primary sortas="b-ata_id">ata_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="cdrom_id">
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<term><command>cdrom_id</command></term>
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<listitem>
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<para>Provides Udev with the capabilities of a
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CD-ROM or DVD-ROM drive</para>
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<indexterm zone="ch-system-udev cdrom_id">
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<primary sortas="b-cdrom_id">cdrom_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="create_floppy_devices">
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<term><command>create_floppy_devices</command></term>
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<listitem>
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<para>Creates all possible floppy devices based on the CMOS type</para>
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<indexterm zone="ch-system-udev create_floppy_devices">
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<primary sortas="b-create_floppy_devices">create_floppy_devices</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="edd_id">
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<term><command>edd_id</command></term>
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<listitem>
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<para>Provides Udev with the EDD ID for a BIOS disk drive</para>
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<indexterm zone="ch-system-udev edd_id">
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<primary sortas="b-edd_id">edd_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="firmware_helper">
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<term><command>firmware_helper</command></term>
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<listitem>
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<para>Uploads firmware to devices</para>
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<indexterm zone="ch-system-udev firmware_helper">
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<primary sortas="b-firmware_helper">firmware_helper</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="path_id">
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<term><command>path_id</command></term>
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<listitem>
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<para>Provide the shortest possible unique hardware path to a
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device</para>
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<indexterm zone="ch-system-udev path_id">
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<primary sortas="b-path_id">path_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="scsi_id">
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<term><command>scsi_id</command></term>
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<listitem>
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<para>Provides Udev with a unique SCSI identifier
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based on the data returned from sending a SCSI INQUIRY command to
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the specified device</para>
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<indexterm zone="ch-system-udev scsi_id">
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<primary sortas="b-scsi_id">scsi_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevcontrol">
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<term><command>udevcontrol</command></term>
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<listitem>
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<para>Configures a number of options for the running
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<command>udevd</command> daemon, such as the log level.</para>
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<indexterm zone="ch-system-udev udevcontrol">
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<primary sortas="b-udevcontrol">udevcontrol</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevd">
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<term><command>udevd</command></term>
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<listitem>
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<para>A daemon that listens for uevents on the netlink socket,
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creates devices and runs the configured external programs in
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response to these uevents</para>
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<indexterm zone="ch-system-udev udevd">
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<primary sortas="b-udevd">udevd</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevinfo">
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<term><command>udevinfo</command></term>
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<listitem>
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<para>Allows users to query the Udev database for
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information on any device currently present on the system; it also
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provides a way to query any device in the <systemitem
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class="filesystem">sysfs</systemitem> tree to help create udev
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rules</para>
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<indexterm zone="ch-system-udev udevinfo">
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<primary sortas="b-udevinfo">udevinfo</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevmonitor">
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<term><command>udevmonitor</command></term>
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<listitem>
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<para>Prints the event received from the kernel and the environment
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which Udev sends out after rule processing</para>
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<indexterm zone="ch-system-udev udevmonitor">
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<primary sortas="b-udevmonitor">udevmonitor</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevsettle">
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<term><command>udevsettle</command></term>
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<listitem>
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<para>Watches the Udev event queue and exits if all current uevents
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have been handled</para>
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<indexterm zone="ch-system-udev udevsettle">
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<primary sortas="b-udevsettle">udevsettle</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevtest">
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<term><command>udevtest</command></term>
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<listitem>
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<para>Simulates a uevent for the given device, and prints out the
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name of the node the real <command>udevd</command> would have created,
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or the name of the renamed network interface</para>
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<indexterm zone="ch-system-udev udevtest">
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<primary sortas="b-udevtest">udevtest</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="udevtrigger">
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<term><command>udevtrigger</command></term>
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<listitem>
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<para>Triggers kernel device uevents to be replayed</para>
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<indexterm zone="ch-system-udev udevtrigger">
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<primary sortas="b-udevtrigger">udevtrigger</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="usb_id">
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<term><command>usb_id</command></term>
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<listitem>
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<para>Provides Udev with information about USB
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devices</para>
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<indexterm zone="ch-system-udev usb_id">
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<primary sortas="b-usb_id">usb_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="vol_id">
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<term><command>vol_id</command></term>
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<listitem>
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<para>Provides Udev with the label and uuid of a
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filesystem</para>
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<indexterm zone="ch-system-udev vol_id">
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<primary sortas="b-vol_id">vol_id</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="etc-udev">
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<term><filename class="directory">/etc/udev</filename></term>
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<listitem>
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<para>Contains Udev configuation files,
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device permissions, and rules for device naming</para>
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<indexterm zone="ch-system-udev etc-udev">
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<primary sortas="e-/etc/udev">/etc/udev</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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</sect1>
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