1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
---|
2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
---|
3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ |
---|
4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
---|
5 | %general-entities; |
---|
6 | ]> |
---|
7 | |
---|
8 | <sect1 id="ch-final-system-creatingfiles"> |
---|
9 | <?dbhtml filename="creatingfiles.html"?> |
---|
10 | |
---|
11 | <title>Creating the passwd, group, and log Files</title> |
---|
12 | |
---|
13 | <indexterm zone="ch-final-system-creatingfiles"> |
---|
14 | <primary sortas="e-/etc/passwd">/etc/passwd</primary> |
---|
15 | </indexterm> |
---|
16 | |
---|
17 | <indexterm zone="ch-final-system-creatingfiles"> |
---|
18 | <primary sortas="e-/etc/group">/etc/group</primary> |
---|
19 | </indexterm> |
---|
20 | |
---|
21 | <indexterm zone="ch-final-system-creatingfiles"> |
---|
22 | <primary sortas="e-/var/run/utmp">/var/run/utmp</primary> |
---|
23 | </indexterm> |
---|
24 | |
---|
25 | <indexterm zone="ch-final-system-creatingfiles"> |
---|
26 | <primary sortas="e-/var/log/btmp">/var/log/btmp</primary> |
---|
27 | </indexterm> |
---|
28 | |
---|
29 | <indexterm zone="ch-final-system-creatingfiles"> |
---|
30 | <primary sortas="e-/var/log/lastlog">/var/log/lastlog</primary> |
---|
31 | </indexterm> |
---|
32 | |
---|
33 | <indexterm zone="ch-final-system-creatingfiles"> |
---|
34 | <primary sortas="e-/var/log/wtmp">/var/log/wtmp</primary> |
---|
35 | </indexterm> |
---|
36 | |
---|
37 | <para>A proper Linux system maintains a list of the mounted file systems in |
---|
38 | the file <filename>/etc/mtab</filename>. With the way our embedded system is |
---|
39 | is designed, we will be using a symlink to <filename>/proc/mounts</filename>:</para> |
---|
40 | |
---|
41 | <screen><userinput>ln -svf ../proc/mounts ${CLFS}/targetfs/etc/mtab</userinput></screen> |
---|
42 | |
---|
43 | <para>In order for user <systemitem class="username">root</systemitem> to be |
---|
44 | able to login and for the name <quote>root</quote> to be recognized, there |
---|
45 | must be relevant entries in the <filename>/etc/passwd</filename> and |
---|
46 | <filename>/etc/group</filename> files.</para> |
---|
47 | |
---|
48 | <para>Create the <filename>/etc/passwd</filename> file by running the following |
---|
49 | command:</para> |
---|
50 | |
---|
51 | <screen><userinput>cat > ${CLFS}/targetfs/etc/passwd << "EOF" |
---|
52 | <literal>root::0:0:root:/root:/bin/ash</literal> |
---|
53 | EOF</userinput></screen> |
---|
54 | |
---|
55 | <para>The actual password for <systemitem class="username">root</systemitem> |
---|
56 | (the <quote>::</quote> used here is just a placeholder and allow you to login |
---|
57 | with no password) will be set later.</para> |
---|
58 | |
---|
59 | <para>Create the <filename>/etc/group</filename> file by running the following |
---|
60 | command:</para> |
---|
61 | |
---|
62 | <screen><userinput>cat > ${CLFS}/targetfs/etc/group << "EOF" |
---|
63 | <literal>root:x:0: |
---|
64 | bin:x:1: |
---|
65 | users:x:1000: |
---|
66 | nogroup:x:65533: |
---|
67 | nobody:x:65534:</literal> |
---|
68 | EOF</userinput></screen> |
---|
69 | |
---|
70 | <para>The created groups are not part of any standard. The Linux Standard |
---|
71 | Base (LSB, available at <ulink url="http://www.linuxbase.org"/>) recommends |
---|
72 | only that, besides the group <systemitem class="groupname">root</systemitem> |
---|
73 | with a Group ID (GID) of 0, a group <systemitem |
---|
74 | class="groupname">bin</systemitem> with a GID of 1 be present. All other |
---|
75 | group names and GIDs can be chosen freely by the system administrator since |
---|
76 | well-written programs do not depend on GID numbers, but rather use the |
---|
77 | group's name.</para> |
---|
78 | |
---|
79 | <para>The <command>login</command>, <command>agetty</command>, and |
---|
80 | <command>init</command> programs (and others) use a number of log |
---|
81 | files to record information such as who was logged into the system and |
---|
82 | when. However, these programs will not write to the log files if they |
---|
83 | do not already exist. Initialize the log files and give them |
---|
84 | proper permissions:</para> |
---|
85 | |
---|
86 | <screen><userinput>touch ${CLFS}/targetfs/var/run/utmp ${CLFS}/targetfs/var/log/{btmp,lastlog,wtmp} |
---|
87 | chmod -v 664 ${CLFS}/targetfs/var/run/utmp ${CLFS}/targetfs/var/log/lastlog</userinput></screen> |
---|
88 | |
---|
89 | <para>The <filename>/var/run/utmp</filename> file records the users |
---|
90 | that are currently logged in. The <filename>/var/log/wtmp</filename> |
---|
91 | file records all logins and logouts. The |
---|
92 | <filename>/var/log/lastlog</filename> file records when |
---|
93 | each user last logged in. The <filename>/var/log/btmp</filename> file |
---|
94 | records the bad login attempts.</para> |
---|
95 | |
---|
96 | </sect1> |
---|