| 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/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="postlfs-users-groups" xreflabel="About System Users and Groups">
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| 9 | <?dbhtml filename="users.html"?>
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| 10 |
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| 11 | <sect1info>
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| 12 | <othername>$LastChangedBy$</othername>
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| 13 | <date>$Date$</date>
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| 14 | </sect1info>
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| 15 |
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| 16 | <title>About System Users and Groups</title>
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| 17 |
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| 18 | <indexterm zone="postlfs-users-groups">
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| 19 | <primary sortas="e-etc-passwd">/etc/passwd</primary>
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| 20 | </indexterm>
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| 21 |
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| 22 | <indexterm zone="postlfs-users-groups">
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| 23 | <primary sortas="e-etc-group">/etc/group</primary>
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| 24 | </indexterm>
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| 25 |
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| 26 | <indexterm zone="postlfs-users-groups">
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| 27 | <primary sortas="e-etc-login.defs">/etc/login.defs</primary>
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| 28 | </indexterm>
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| 29 |
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| 30 | <para>
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| 31 | Throughout BLFS, many packages install programs that run as daemons or in
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| 32 | some way should have a user or group name assigned. Generally these
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| 33 | names are used to map a user ID (uid) or group ID (gid) for system use.
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| 34 | Generally the specific uid or gid numbers used by these applications are
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| 35 | not significant. The exception of course, is that <systemitem
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| 36 | class='username'>root</systemitem> has a uid and gid of 0 (zero) that
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| 37 | is indeed special. The uid values are stored in
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| 38 | <filename>/etc/passwd</filename> and the gid values are found in
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| 39 | <filename>/etc/group</filename>.
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| 40 | </para>
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| 41 |
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| 42 | <para>
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| 43 | Customarily, Unix systems classify users and groups into two categories:
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| 44 | system users and regular users. The system users and groups are given
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| 45 | low numbers and regular users and groups have numeric values greater
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| 46 | than all the system values. The cutoff for these numbers is found in
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| 47 | two parameters in the <filename>/etc/login.defs</filename> configuration
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| 48 | file. The default UID_MIN value is 1000 and the default GID_MIN value
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| 49 | is 1000. If a specific uid or gid value is not specified when creating
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| 50 | a user with <command>useradd</command> or a group with
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| 51 | <command>groupadd</command> the values assigned will always be above
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| 52 | these cutoff values.
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| 53 | </para>
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| 54 |
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| 55 | <para>
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| 56 | Additionally, the <ulink url=
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| 57 | "http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/usernames.html">
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| 58 | Linux Standard Base</ulink> recommends that system uid and gid values
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| 59 | should be below 100.
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| 60 | </para>
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| 61 |
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| 62 | <para>
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| 63 | Below is a table of suggested uid/gid values used in BLFS beyond those
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| 64 | defined in a base LFS installation. These can be changed as desired, but
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| 65 | provide a suggested set of consistent values.
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| 66 | </para>
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| 67 |
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| 68 | <table id="uidgid" class="uidvalues">
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| 69 | <title>UID/GID Suggested Values</title>
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| 70 | <?dbfo table-width="2in" ?>
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| 71 | <tgroup cols="3">
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| 72 | <colspec colnum="1" colwidth="1.2in"/>
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| 73 | <colspec colnum="2" colwidth=".4in"/>
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| 74 | <colspec colnum="3" colwidth=".4in"/>
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| 75 | <thead>
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| 76 | <row><entry>Name</entry><entry>uid</entry><entry>gid</entry></row>
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| 77 | </thead>
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| 78 | <tbody>
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| 79 | <row><entry>bin </entry><entry> 1</entry><entry> </entry></row>
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| 80 | <row><entry>lp </entry><entry> 9</entry><entry> </entry></row>
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| 81 | <!--<row><entry>usb </entry><entry> </entry><entry>14</entry></row> -->
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| 82 | <row><entry>adm </entry><entry> </entry><entry>16</entry></row>
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| 83 | <row><entry>atd </entry><entry>17</entry><entry>17</entry></row>
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| 84 | <row><entry>messagebus</entry><entry>18</entry><entry>18</entry></row>
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| 85 | <row><entry>lpadmin </entry><entry></entry><entry>19</entry></row>
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| 86 | <row><entry>named </entry><entry>20</entry><entry>20</entry></row>
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| 87 | <row><entry>gdm </entry><entry>21</entry><entry>21</entry></row>
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| 88 | <row><entry>fcron </entry><entry>22</entry><entry>22</entry></row>
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| 89 | <row><entry>systemd-journal</entry><entry></entry><entry>23</entry></row>
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| 90 | <row><entry>apache </entry><entry>25</entry><entry>25</entry></row>
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| 91 | <row><entry>smmsp </entry><entry>26</entry><entry>26</entry></row>
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| 92 | <row><entry>polkitd </entry><entry>27</entry><entry>27</entry></row>
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| 93 | <row><entry>rpc </entry><entry>28</entry><entry>28</entry></row>
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| 94 | <!-- <row><entry>courier </entry><entry>30</entry><entry>30</entry></row> -->
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| 95 | <row><entry>exim </entry><entry>31</entry><entry>31</entry></row>
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| 96 | <row><entry>postfix </entry><entry>32</entry><entry>32</entry></row>
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| 97 | <row><entry>postdrop</entry><entry> </entry><entry>33</entry></row>
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| 98 | <row><entry>sendmail</entry><entry>34</entry><entry> </entry></row>
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| 99 | <row><entry>mail </entry><entry> </entry><entry>34</entry></row>
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| 100 | <row><entry>vmailman</entry><entry>35</entry><entry>35</entry></row>
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| 101 | <row><entry>news </entry><entry>36</entry><entry>36</entry></row>
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| 102 | <row><entry>kdm </entry><entry>37</entry><entry>37</entry></row>
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| 103 | <row><entry>fetchmail</entry><entry>38</entry><entry> </entry></row>
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| 104 | <row><entry>mysql </entry><entry>40</entry><entry>40</entry></row>
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| 105 | <row><entry>postgres</entry><entry>41</entry><entry>41</entry></row>
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| 106 | <row><entry>dovecot </entry><entry>42</entry><entry>42</entry></row>
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| 107 | <row><entry>dovenull</entry><entry>43</entry><entry>43</entry></row>
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| 108 | <row><entry>ftp </entry><entry>45</entry><entry>45</entry></row>
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| 109 | <row><entry>proftpd </entry><entry>46</entry><entry>46</entry></row>
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| 110 | <row><entry>vsftpd </entry><entry>47</entry><entry>47</entry></row>
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| 111 | <row><entry>rsyncd </entry><entry>48</entry><entry>48</entry></row>
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| 112 | <row><entry>sshd </entry><entry>50</entry><entry>50</entry></row>
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| 113 | <row><entry>stunnel </entry><entry>51</entry><entry>51</entry></row>
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| 114 | <row><entry>svn </entry><entry>56</entry><entry>56</entry></row>
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| 115 | <row><entry>svntest </entry><entry> </entry><entry>57</entry></row>
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| 116 | <!-- <row><entry>pulse </entry><entry>58</entry><entry>58</entry></row>
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| 117 | <row><entry>pulse-access</entry><entry></entry><entry>59</entry></row>
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| 118 | -->
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| 119 | <row><entry>games </entry><entry>60</entry><entry>60</entry></row>
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| 120 | <row><entry>kvm </entry><entry> </entry><entry>61</entry></row>
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| 121 | <row><entry>wireshark</entry><entry> </entry><entry>62</entry></row>
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| 122 | <row><entry>lightdm </entry><entry>63</entry><entry>63</entry></row>
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| 123 | <row><entry>sddm </entry><entry>64</entry><entry>64</entry></row>
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| 124 | <row><entry>lightdm </entry><entry>65</entry><entry>65</entry></row>
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| 125 | <row><entry>scanner </entry><entry> </entry><entry>70</entry></row>
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| 126 | <row><entry>colord </entry><entry>71</entry><entry>71</entry></row>
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| 127 |
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| 128 | <!-- Begin systemd specific users and groups -->
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| 129 | <row><entry>systemd-bus-proxy</entry><entry>72</entry><entry>72</entry></row>
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| 130 | <row><entry>systemd-journal-gateway</entry><entry>73</entry><entry>73</entry></row>
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| 131 | <row><entry>systemd-journal-remote</entry><entry>74</entry><entry>74</entry></row>
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| 132 | <row><entry>systemd-journal-upload</entry><entry>75</entry><entry>75</entry></row>
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| 133 | <row><entry>systemd-network</entry><entry>76</entry><entry>76</entry></row>
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| 134 | <row><entry>systemd-resolve</entry><entry>77</entry><entry>77</entry></row>
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| 135 | <row><entry>systemd-timesync</entry><entry>78</entry><entry>78</entry></row>
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| 136 | <row><entry>systemd-coredump</entry><entry>79</entry><entry>79</entry></row>
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| 137 | <!-- End systemd specific users and groups -->
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| 138 |
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| 139 | <row><entry>ldap </entry><entry>83</entry><entry>83</entry></row>
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| 140 | <row><entry>avahi </entry><entry>84</entry><entry>84</entry></row>
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| 141 | <row><entry>avahi-autoipd</entry><entry>85</entry><entry>85</entry></row>
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| 142 | <row><entry>netdev </entry><entry> </entry><entry>86</entry></row>
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| 143 | <row><entry>ntp </entry><entry>87</entry><entry>87</entry></row>
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| 144 | <row><entry>unbound </entry><entry>88</entry><entry>88</entry></row>
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| 145 | <row><entry>plugdev </entry><entry> </entry><entry>90</entry></row>
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| 146 | <row><entry>wheel </entry><entry> </entry><entry>97</entry></row>
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| 147 | <row><entry>anonymous</entry><entry>98</entry><entry> </entry></row>
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| 148 | <row><entry>nobody </entry><entry>99</entry><entry> </entry></row>
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| 149 | <row><entry>nogroup </entry><entry> </entry><entry>99</entry></row>
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| 150 | </tbody>
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| 151 | </tgroup>
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| 152 | </table>
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| 153 |
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| 154 | <para>
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| 155 | One value that is missing is 65534. This value is customarily assigned
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| 156 | to the user <systemitem class="username">nobody</systemitem> and group
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| 157 | <systemitem class="groupname">nogroup</systemitem> and is unnecessary.
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| 158 | </para>
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| 159 |
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| 160 | </sect1>
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