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- <?xml version="1.0" encoding="ISO-8859-1"?>
- <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
- "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
- <!ENTITY % general-entities SYSTEM "../general.ent">
- %general-entities;
- ]>
- <sect1 id="ch-tools-createfiles">
- <?dbhtml filename="createfiles.html"?>
- <title>Creating Essential Files and Symlinks</title>
- <indexterm zone="ch-tools-createfiles">
- <primary sortas="e-/etc/passwd">/etc/passwd</primary>
- </indexterm>
- <indexterm zone="ch-tools-createfiles">
- <primary sortas="e-/etc/group">/etc/group</primary>
- </indexterm>
- <indexterm zone="ch-tools-createfiles">
- <primary sortas="e-/run/utmp">/run/utmp</primary>
- </indexterm>
- <indexterm zone="ch-tools-createfiles">
- <primary sortas="e-/var/log/btmp">/var/log/btmp</primary>
- </indexterm>
- <indexterm zone="ch-tools-createfiles">
- <primary sortas="e-/var/log/lastlog">/var/log/lastlog</primary>
- </indexterm>
- <indexterm zone="ch-tools-createfiles">
- <primary sortas="e-/var/log/wtmp">/var/log/wtmp</primary>
- </indexterm>
- <para>Historically, Linux maintains a list of the mounted file systems in the
- file <filename>/etc/mtab</filename>. Modern kernels maintain this list
- internally and exposes it to the user via the <filename
- class="directory">/proc</filename> filesystem. To satisfy utilities that
- expect the presence of <filename>/etc/mtab</filename>, create the following
- symbolic link:</para>
- <screen><userinput>ln -sv /proc/self/mounts /etc/mtab</userinput></screen>
- <para>Create a basic <filename>/etc/hosts</filename> file to be
- referenced in some test suites, and in one of Perl's configuration files
- as well:</para>
- <screen><userinput>echo "127.0.0.1 localhost $(hostname)" > /etc/hosts</userinput></screen>
- <para>In order for user <systemitem class="username">root</systemitem> to be
- able to login and for the name <quote>root</quote> to be recognized, there
- must be relevant entries in the <filename>/etc/passwd</filename> and
- <filename>/etc/group</filename> files.</para>
- <para>Create the <filename>/etc/passwd</filename> file by running the following
- command:</para>
- <screen revision="sysv"><userinput>cat > /etc/passwd << "EOF"
- <literal>root:x:0:0:root:/root:/bin/bash
- bin:x:1:1:bin:/dev/null:/bin/false
- daemon:x:6:6:Daemon User:/dev/null:/bin/false
- messagebus:x:18:18:D-Bus Message Daemon User:/run/dbus:/bin/false
- uuidd:x:80:80:UUID Generation Daemon User:/dev/null:/bin/false
- nobody:x:99:99:Unprivileged User:/dev/null:/bin/false</literal>
- EOF</userinput></screen>
- <screen revision="systemd"><userinput>cat > /etc/passwd << "EOF"
- <literal>root:x:0:0:root:/root:/bin/bash
- bin:x:1:1:bin:/dev/null:/bin/false
- daemon:x:6:6:Daemon User:/dev/null:/bin/false
- messagebus:x:18:18:D-Bus Message Daemon User:/run/dbus:/bin/false
- systemd-bus-proxy:x:72:72:systemd Bus Proxy:/:/bin/false
- systemd-journal-gateway:x:73:73:systemd Journal Gateway:/:/bin/false
- systemd-journal-remote:x:74:74:systemd Journal Remote:/:/bin/false
- systemd-journal-upload:x:75:75:systemd Journal Upload:/:/bin/false
- systemd-network:x:76:76:systemd Network Management:/:/bin/false
- systemd-resolve:x:77:77:systemd Resolver:/:/bin/false
- systemd-timesync:x:78:78:systemd Time Synchronization:/:/bin/false
- systemd-coredump:x:79:79:systemd Core Dumper:/:/bin/false
- uuidd:x:80:80:UUID Generation Daemon User:/dev/null:/bin/false
- nobody:x:99:99:Unprivileged User:/dev/null:/bin/false</literal>
- EOF</userinput></screen>
- <para>The actual password for <systemitem class="username">root</systemitem>
- will be set later.</para>
- <para>Create the <filename>/etc/group</filename> file by running the following
- command:</para>
- <screen revision="sysv"><userinput>cat > /etc/group << "EOF"
- <literal>root:x:0:
- bin:x:1:daemon
- sys:x:2:
- kmem:x:3:
- tape:x:4:
- tty:x:5:
- daemon:x:6:
- floppy:x:7:
- disk:x:8:
- lp:x:9:
- dialout:x:10:
- audio:x:11:
- video:x:12:
- utmp:x:13:
- usb:x:14:
- cdrom:x:15:
- adm:x:16:
- messagebus:x:18:
- input:x:24:
- mail:x:34:
- kvm:x:61:
- uuidd:x:80:
- wheel:x:97:
- nogroup:x:99:
- users:x:999:</literal>
- EOF</userinput></screen>
- <screen revision="systemd"><userinput>cat > /etc/group << "EOF"
- <literal>root:x:0:
- bin:x:1:daemon
- sys:x:2:
- kmem:x:3:
- tape:x:4:
- tty:x:5:
- daemon:x:6:
- floppy:x:7:
- disk:x:8:
- lp:x:9:
- dialout:x:10:
- audio:x:11:
- video:x:12:
- utmp:x:13:
- usb:x:14:
- cdrom:x:15:
- adm:x:16:
- messagebus:x:18:
- systemd-journal:x:23:
- input:x:24:
- mail:x:34:
- kvm:x:61:
- systemd-bus-proxy:x:72:
- systemd-journal-gateway:x:73:
- systemd-journal-remote:x:74:
- systemd-journal-upload:x:75:
- systemd-network:x:76:
- systemd-resolve:x:77:
- systemd-timesync:x:78:
- systemd-coredump:x:79:
- uuidd:x:80:
- wheel:x:97:
- nogroup:x:99:
- users:x:999:</literal>
- EOF</userinput></screen>
- <para>The created groups are not part of any standard—they are groups
- decided on in part by the requirements of the Udev configuration in Chapter
- 9, and in part by common convention employed by a number of existing Linux
- distributions. In addition, some test suites rely on specific users or
- groups. The Linux Standard Base (LSB, available at <ulink
- url="http://refspecs.linuxfoundation.org/lsb.shtml"/>) only recommends that,
- besides the group <systemitem class="groupname">root</systemitem> with a
- Group ID (GID) of 0, a group <systemitem class="groupname">bin</systemitem>
- with a GID of 1 be present. All other group names and GIDs can be chosen
- freely by the system administrator since well-written programs do not depend
- on GID numbers, but rather use the group's name.</para>
- <para>Some tests in <xref linkend="chapter-building-system"/> need a regular
- user. We add this user here and delete this account at the end of that
- chapter.</para>
- <screen><userinput>echo "tester:x:$(ls -n $(tty) | cut -d" " -f3):101::/home/tester:/bin/bash" >> /etc/passwd
- echo "tester:x:101:" >> /etc/group
- install -o tester -d /home/tester</userinput></screen>
- <para>To remove the <quote>I have no name!</quote> prompt, start a new
- shell. Since the
- <filename>/etc/passwd</filename> and <filename>/etc/group</filename>
- files have been created, user name and group name resolution will now
- work:</para>
- <screen role="nodump"><userinput>exec /bin/bash --login +h</userinput></screen>
- <para>Note the use of the <parameter>+h</parameter> directive. This tells
- <command>bash</command> not to use its internal path hashing. Without this
- directive, <command>bash</command> would remember the paths to binaries it has
- executed. To ensure the use of the newly compiled binaries as soon as they are
- installed, the <parameter>+h</parameter> directive will be used for the duration
- of this and the next chapter.</para>
- <para>The <command>login</command>, <command>agetty</command>, and
- <command>init</command> programs (and others) use a number of log
- files to record information such as who was logged into the system and
- when. However, these programs will not write to the log files if they
- do not already exist. Initialize the log files and give them
- proper permissions:</para>
- <screen><userinput>touch /var/log/{btmp,lastlog,faillog,wtmp}
- chgrp -v utmp /var/log/lastlog
- chmod -v 664 /var/log/lastlog
- chmod -v 600 /var/log/btmp</userinput></screen>
- <para>The <filename>/var/log/wtmp</filename> file records all logins and
- logouts. The <filename>/var/log/lastlog</filename> file records when each
- user last logged in. The <filename>/var/log/faillog</filename> file records
- failed login attempts. The <filename>/var/log/btmp</filename> file records
- the bad login attempts.</para>
- <note><para>The <filename>/run/utmp</filename> file records the users that
- are currently logged in. This file is created dynamically in the boot
- scripts.</para></note>
- </sect1>
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