1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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3 | "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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5 | %general-entities;
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6 | ]>
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7 |
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8 | <sect1 id="ch-system-udev" role="wrap">
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9 | <?dbhtml filename="udev.html"?>
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10 |
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11 | <title>Udev-&udev-version;</title>
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12 |
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13 | <indexterm zone="ch-system-udev">
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14 | <primary sortas="a-Udev">Udev</primary>
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15 | </indexterm>
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16 |
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17 | <sect2 role="package">
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18 | <title/>
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19 |
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20 | <para>The Udev package contains programs for dynamic creation of device
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21 | nodes.</para>
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22 |
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23 | <segmentedlist>
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24 | <segtitle>&buildtime;</segtitle>
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25 | <segtitle>&diskspace;</segtitle>
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26 |
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27 | <seglistitem>
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28 | <seg>0.1 SBU</seg>
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29 | <seg>4.8 MB</seg>
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30 | </seglistitem>
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31 | </segmentedlist>
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32 |
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33 | </sect2>
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34 |
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35 | <sect2 role="installation">
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36 | <title>Installation of Udev</title>
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37 |
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38 | <para>Create some devices and directories that Udev cannot handle due to
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39 | them being required very early in the boot process:</para>
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40 |
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41 | <screen><userinput>install -dv /lib/{firmware,udev/devices/{pts,shm}}
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42 | mknod -m0666 /lib/udev/devices/null c 1 3
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43 | ln -sv /proc/self/fd /lib/udev/devices/fd
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44 | ln -sv /proc/self/fd/0 /lib/udev/devices/stdin
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45 | ln -sv /proc/self/fd/1 /lib/udev/devices/stdout
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46 | ln -sv /proc/self/fd/2 /lib/udev/devices/stderr
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47 | ln -sv /proc/kcore /lib/udev/devices/core</userinput></screen>
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48 |
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49 | <para>Compile the package:</para>
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50 |
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51 | <screen><userinput>make EXTRAS="extras/ata_id extras/cdrom_id extras/edd_id \
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52 | extras/firmware extras/floppy extras/scsi_id \
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53 | extras/usb_id extras/volume_id"</userinput></screen>
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54 |
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55 | <variablelist>
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56 | <title>The meaning of the make option:</title>
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57 |
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58 | <varlistentry>
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59 | <term><parameter>EXTRAS=...</parameter></term>
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60 | <listitem>
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61 | <para>This builds several helper binaries that can aid in writing custom
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62 | Udev rules.</para>
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63 | </listitem>
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64 | </varlistentry>
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65 |
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66 | </variablelist>
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67 |
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68 | <para>To test the results, issue:
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69 | <userinput>make test</userinput>.</para>
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70 |
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71 | <para>Install the package:</para>
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72 |
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73 | <screen><userinput>make DESTDIR=/ \
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74 | EXTRAS="extras/ata_id extras/cdrom_id extras/edd_id \
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75 | extras/firmware extras/floppy extras/scsi_id \
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76 | extras/usb_id extras/volume_id" install</userinput></screen>
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77 |
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78 | <variablelist>
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79 | <title>The meaning of the make parameter:</title>
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80 |
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81 | <varlistentry>
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82 | <term><parameter>DESTDIR=/</parameter></term>
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83 | <listitem>
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84 | <para>This prevents the Udev build process from killing any
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85 | <command>udevd</command> processes that may be running on the
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86 | host system.</para>
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87 | </listitem>
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88 | </varlistentry>
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89 |
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90 | </variablelist>
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91 |
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92 | <para>Udev's configuration is far from ideal by default, so install
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93 | the configuration files here:</para>
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94 |
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95 | <screen><userinput>cp -v ../&udev-config-file; /etc/udev/rules.d/25-lfs.rules</userinput></screen>
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96 |
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97 | <para>Create some rules that work around broken sysfs attribute creation
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98 | timing in linux-2.6.15:</para>
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99 |
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100 | <screen><userinput>cat > /etc/udev/rules.d/10-wait_for_sysfs.rules << "EOF"
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101 | ACTION=="add", DEVPATH=="/devices/*", ENV{PHYSDEVBUS}=="?*", WAIT_FOR_SYSFS="bus"
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102 | ACTION=="add", SUBSYSTEM=="net", WAIT_FOR_SYSFS="address"
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103 | EOF</userinput></screen>
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104 |
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105 | <para>Install the documentation that explains how to create Udev rules:</para>
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106 |
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107 | <screen><userinput>install -m644 -D -v docs/writing_udev_rules/index.html /usr/share/doc/udev-&udev-version;/index.html</userinput></screen>
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108 |
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109 | <important>
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110 |
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111 | <para>When Udev is started by the LFS-Bootscripts, a replay of all kernel
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112 | device events happens. These events tell Udev what devices exist.
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113 | Sometimes the Udev bootscript doesn't wait long enough for
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114 | <command>udevd</command> to process all of the replayed events and
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115 | consequently the devices for those missed events are not created before the
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116 | script exits. Since <command>udevd</command> is still running in the
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117 | background, the devices will be created a few milliseconds later, but the
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118 | next bootscript to run may require a device to exist before it has been
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119 | created. To avoid such missed events, and to avoid hardcoding an overly
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120 | long wait time, It is recommended that you run the following commands to
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121 | aid the LFS development team in debugging these missed events and finding
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122 | an acceptable solution more quickly.</para>
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123 |
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124 | <para>First, create a simple C file:</para>
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125 |
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126 | <screen><userinput>cat > bug.c << EOF
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127 | <literal>/* Simple event recorder */
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128 | #define _GNU_SOURCE
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129 | #include <sys/types.h>
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130 | #include <sys/stat.h>
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131 | #include <fcntl.h>
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132 | #include <unistd.h>
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133 | #include <stdlib.h>
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134 | #include <argz.h>
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135 | int main(int argc, char * argv[])
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136 | {
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137 | char * envz;
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138 | size_t len;
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139 | int bug;
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140 | bug = open("/dev/bug", O_WRONLY | O_APPEND);
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141 | if (bug == -1)
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142 | return 0;
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143 | setenv("_SEPARATOR", "--------------------------------------", 1);
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144 | argz_create(environ, &envz, &len);
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145 | argz_stringify(envz, len, '\n');
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146 | envz[len-1]='\n';
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147 | write(bug, envz, len);
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148 | close(bug);
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149 | free(envz);
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150 | return 0;
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151 | }</literal>
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152 | EOF</userinput></screen>
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153 |
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154 | <para>Now compile it:</para>
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155 |
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156 | <screen><userinput>gcc -o /lib/udev/bug bug.c</userinput></screen>
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157 |
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158 | <para>The next step adds a simple logging rule to run this program.</para>
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159 |
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160 | <screen><userinput>cat > /etc/udev/rules.d/90-bug.rules << "EOF"
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161 | <literal>ACTION=="add", RUN+="bug"</literal>
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162 | EOF</userinput></screen>
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163 |
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164 | <para>When booting the new LFS system, if any events are missed, a warning
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165 | message will appear and a <filename>/dev/bugreport</filename> file will be
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166 | created. The warning message will tell you where to send feedback.</para>
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167 |
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168 | </important>
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169 |
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170 | </sect2>
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171 |
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172 | <sect2 id="contents-udev" role="content">
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173 | <title>Contents of Udev</title>
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174 |
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175 | <segmentedlist>
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176 | <segtitle>Installed programs</segtitle>
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177 | <segtitle>Installed directory</segtitle>
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178 |
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179 | <seglistitem>
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180 | <seg>ata_id, cdrom_id, create_floppy_devices, edd_id, firmware_helper,
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181 | scsi_id, udevcontrol, udevd, udevinfo, udevmonitor, udevtest, usb_id
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182 | and vol_id</seg>
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183 | <seg>/etc/udev</seg>
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184 | </seglistitem>
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185 | </segmentedlist>
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186 |
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187 | <variablelist>
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188 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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189 | <?dbfo list-presentation="list"?>
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190 | <?dbhtml list-presentation="table"?>
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191 |
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192 | <varlistentry id="ata_id">
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193 | <term><command>ata_id</command></term>
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194 | <listitem>
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195 | <para>Provides Udev with a unique string and
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196 | additional information (uuid, label) for an ATA drive</para>
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197 | <indexterm zone="ch-system-udev ata_id">
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198 | <primary sortas="b-ata_id">ata_id</primary>
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199 | </indexterm>
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200 | </listitem>
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201 | </varlistentry>
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202 |
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203 | <varlistentry id="cdrom_id">
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204 | <term><command>cdrom_id</command></term>
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205 | <listitem>
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206 | <para>Provides Udev with the capabilities of a
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207 | CD-ROM or DVD-ROM drive</para>
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208 | <indexterm zone="ch-system-udev cdrom_id">
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209 | <primary sortas="b-cdrom_id">cdrom_id</primary>
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210 | </indexterm>
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211 | </listitem>
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212 | </varlistentry>
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213 |
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214 | <varlistentry id="create_floppy_devices">
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215 | <term><command>create_floppy_devices</command></term>
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216 | <listitem>
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217 | <para>Creates all possible floppy devices based on the CMOS type</para>
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218 | <indexterm zone="ch-system-udev create_floppy_devices">
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219 | <primary sortas="b-create_floppy_devices">create_floppy_devices</primary>
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220 | </indexterm>
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221 | </listitem>
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222 | </varlistentry>
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223 |
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224 | <varlistentry id="edd_id">
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225 | <term><command>edd_id</command></term>
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226 | <listitem>
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227 | <para>Provides Udev with the EDD ID for a BIOS disk drive</para>
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228 | <indexterm zone="ch-system-udev edd_id">
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229 | <primary sortas="b-edd_id">edd_id</primary>
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230 | </indexterm>
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231 | </listitem>
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232 | </varlistentry>
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233 |
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234 | <varlistentry id="firmware_helper">
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235 | <term><command>firmware_helper</command></term>
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236 | <listitem>
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237 | <para>Uploads firmware to devices</para>
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238 | <indexterm zone="ch-system-udev firmware_helper">
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239 | <primary sortas="b-firmware_helper">firmware_helper</primary>
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240 | </indexterm>
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241 | </listitem>
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242 | </varlistentry>
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243 |
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244 | <varlistentry id="scsi_id">
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245 | <term><command>scsi_id</command></term>
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246 | <listitem>
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247 | <para>Provides Udev with a unique SCSI identifier
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248 | based on the data returned from sending a SCSI INQUIRY command to
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249 | the specified device</para>
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250 | <indexterm zone="ch-system-udev scsi_id">
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251 | <primary sortas="b-scsi_id">scsi_id</primary>
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252 | </indexterm>
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253 | </listitem>
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254 | </varlistentry>
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255 |
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256 | <varlistentry id="udevcontrol">
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257 | <term><command>udevcontrol</command></term>
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258 | <listitem>
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259 | <para>Configures a number of options for the running
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260 | <command>udevd</command> daemon, such as the log level.</para>
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261 | <indexterm zone="ch-system-udev udevcontrol">
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262 | <primary sortas="b-udevcontrol">udevcontrol</primary>
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263 | </indexterm>
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264 | </listitem>
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265 | </varlistentry>
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266 |
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267 | <varlistentry id="udevd">
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268 | <term><command>udevd</command></term>
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269 | <listitem>
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270 | <para>A daemon that listens for uevents on the netlink socket,
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271 | creates devices and runs the configured external programs in
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272 | response to these uevents</para>
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273 | <indexterm zone="ch-system-udev udevd">
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274 | <primary sortas="b-udevd">udevd</primary>
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275 | </indexterm>
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276 | </listitem>
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277 | </varlistentry>
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278 |
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279 | <varlistentry id="udevinfo">
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280 | <term><command>udevinfo</command></term>
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281 | <listitem>
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282 | <para>Allows users to query the Udev database for
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283 | information on any device currently present on the system; it also
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284 | provides a way to query any device in the <systemitem
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285 | class="filesystem">sysfs</systemitem> tree to help create udev
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286 | rules</para>
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287 | <indexterm zone="ch-system-udev udevinfo">
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288 | <primary sortas="b-udevinfo">udevinfo</primary>
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289 | </indexterm>
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290 | </listitem>
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291 | </varlistentry>
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292 |
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293 | <varlistentry id="udevmonitor">
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294 | <term><command>udevmonitor</command></term>
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295 | <listitem>
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296 | <para>Prints the event received from the kernel and the environment
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297 | which Udev sends out after rule processing</para>
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298 | <indexterm zone="ch-system-udev udevmonitor">
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299 | <primary sortas="b-udevmonitor">udevmonitor</primary>
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300 | </indexterm>
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301 | </listitem>
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302 | </varlistentry>
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303 |
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304 | <varlistentry id="udevtest">
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305 | <term><command>udevtest</command></term>
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306 | <listitem>
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307 | <para>Simulates a uevent for the given device, and prints out the
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308 | name of the node the real <command>udevd</command> would have created,
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309 | or the name of the renamed network interface</para>
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310 | <indexterm zone="ch-system-udev udevtest">
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311 | <primary sortas="b-udevtest">udevtest</primary>
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312 | </indexterm>
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313 | </listitem>
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314 | </varlistentry>
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315 |
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316 | <varlistentry id="usb_id">
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317 | <term><command>usb_id</command></term>
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318 | <listitem>
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319 | <para>Provides Udev with information about USB
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320 | devices</para>
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321 | <indexterm zone="ch-system-udev usb_id">
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322 | <primary sortas="b-usb_id">usb_id</primary>
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323 | </indexterm>
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324 | </listitem>
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325 | </varlistentry>
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326 |
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327 | <varlistentry id="vol_id">
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328 | <term><command>vol_id</command></term>
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329 | <listitem>
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330 | <para>Provides Udev with the label and uuid of a
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331 | filesystem</para>
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332 | <indexterm zone="ch-system-udev vol_id">
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333 | <primary sortas="b-vol_id">vol_id</primary>
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334 | </indexterm>
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335 | </listitem>
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336 | </varlistentry>
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337 |
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338 | <varlistentry id="etc-udev">
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339 | <term><filename class="directory">/etc/udev</filename></term>
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340 | <listitem>
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341 | <para>Contains Udev configuation files,
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342 | device permissions, and rules for device naming</para>
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343 | <indexterm zone="ch-system-udev etc-udev">
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344 | <primary sortas="e-/etc/udev">/etc/udev</primary>
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345 | </indexterm>
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346 | </listitem>
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347 | </varlistentry>
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348 |
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349 | </variablelist>
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350 |
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351 | </sect2>
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352 |
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353 | </sect1>
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