source: clfs-embedded/BOOK/bootable/common/pwdgroup.xml@ 207e325

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
  "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;
]>

<sect1 id="ch-bootable-pwdgroup">
  <?dbhtml filename="pwdgroup.html"?>

  <title>Creating the passwd, group, and log Files</title>

  <indexterm zone="ch-bootable-pwdgroup">
    <primary sortas="e-/etc/passwd">/etc/passwd</primary>
  </indexterm>

  <indexterm zone="ch-bootable-pwdgroup">
    <primary sortas="e-/etc/group">/etc/group</primary>
  </indexterm>

  <indexterm zone="ch-bootable-pwdgroup">
    <primary sortas="e-/var/run/utmp">/var/run/utmp</primary>
  </indexterm>

  <indexterm zone="ch-bootable-pwdgroup">
    <primary sortas="e-/var/log/btmp">/var/log/btmp</primary>
  </indexterm>

  <indexterm zone="ch-bootable-pwdgroup">
    <primary sortas="e-/var/log/lastlog">/var/log/lastlog</primary>
  </indexterm>

  <indexterm zone="ch-bootable-pwdgroup">
    <primary sortas="e-/var/log/wtmp">/var/log/wtmp</primary>
  </indexterm>

  <para os="a">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 os="b">Create the <filename>${CLFS}/etc/passwd</filename> file by running
  the following command:</para>

<screen os="c"><userinput>cat &gt; ${CLFS}/etc/passwd &lt;&lt; "EOF"
<literal>root::0:0:root:/root:/bin/bash</literal>
EOF</userinput></screen>

  <para os="d">The actual password for <systemitem class="username">root</systemitem>
  (the <quote>::</quote> used here is just a placeholder and allow you to login
  with no password) will be set later.</para>

  <variablelist os="e">
  
    <title>Additional users you may want to add:</title>

    <varlistentry os="e1">
      <term><literal>bin:x:1:1:bin:/bin:/bin/false</literal></term>
      <listitem>
        <para>Can be useful for compatibility with legacy applications.</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e2">
      <term><literal>daemon:x:2:6:daemon:/sbin:/bin/false</literal></term>
      <listitem>
        <para>It is often recommended to use an unprivileged User ID/Group ID
        for daemons to run as, in order to limit their access to the system.</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e3">
      <term><literal>adm:x:3:16:adm:/var/adm:/bin/false</literal></term>
      <listitem>
        <para>Was used for programs that performed administrative tasks.</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e4">
      <term><literal>lp:x:10:9:lp:/var/spool/lp:/bin/false</literal></term>
      <listitem>
        <para>Used by programs for printing</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e5">
      <term><literal>mail:x:30:30:mail:/var/mail:/bin/false</literal></term>
      <listitem>
        <para>Often used by email programs</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e6">
      <term><literal>news:x:31:31:news:/var/spool/news:/bin/false</literal></term>
      <listitem>
        <para>Often used for network news servers</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e7">
      <term><literal>uucp:x:32:32:uucp:/var/spool/uucp:/bin/false</literal></term>
      <listitem>
        <para>Often used for Unix-to-Unix Copy of files from one server to the next</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e8">
      <term><literal>operator:x:50:0:operator:/root:/bin/bash</literal></term>
      <listitem>
        <para>Often used to allow system operators to access the system</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e9">
      <term><literal>postmaster:x:51:30:postmaster:/var/spool/mail:/bin/false</literal></term>
      <listitem>
        <para>Generally used as an account that receives all the information of troubles with the mail server</para>
      </listitem>
    </varlistentry>

    <varlistentry os="e10">
      <term><literal>nobody:x:65534:65534:nobody:/:/bin/false</literal></term>
      <listitem>
        <para>Used by NFS</para>
      </listitem>
    </varlistentry>
  </variablelist>

  <para os="f">Create the <filename>${CLFS}/etc/group</filename> file by running
  the following command:</para>

<screen os="g"><userinput>cat &gt; ${CLFS}/etc/group &lt;&lt; "EOF"
<literal>root:x:0:
bin:x:1:
sys:x:2:
kmem:x:3:
tty:x:4:
tape: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:</literal>
EOF</userinput></screen>

  <variablelist os="h">

    <title>Additional groups you may want to add</title>

    <varlistentry os="h1">
      <term><literal>adm:x:16:root,adm,daemon</literal></term>
      <listitem>
        <para>All users in this group are allowed to do administrative tasks</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h2">
      <term><literal>console:x:17:</literal></term>
      <listitem>
        <para>This group has direct access to the console</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h3">
      <term><literal>cdrw:x:18:</literal></term>
      <listitem>
        <para>This group is allowed to use the CDRW drive</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h4">
      <term><literal>mail:x:30:mail</literal></term>
      <listitem>
        <para>Used by MTAs (Mail Transport Agents)</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h5">
      <term><literal>news:x:31:news</literal></term>
      <listitem>
        <para>Used by Network News Servers</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h5">
      <term><literal>uucp:x:32:uucp</literal></term>
      <listitem>
        <para>Used by the Unix-to-Unix copy users</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h6">
      <term><literal>users:x:1000:</literal></term>
      <listitem>
        <para>The default GID used by shadow for new users</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h7">
      <term><literal>nogroup:x:65533:</literal></term>
      <listitem>
        <para>This is a default group used by some programs that do not
        require a group</para>
      </listitem>
    </varlistentry>

    <varlistentry os="h8">
      <term><literal>nobody:x:65534:</literal></term>
      <listitem>
        <para>This is used by NFS</para>
      </listitem>
    </varlistentry>
  </variablelist>

  <para os="i">The created groups are not part of any standard&mdash;they are
  groups decided on in part by the requirements of the Udev configuration
  in the final system, and in part by common convention employed by a
  number of existing Linux distributions. The Linux Standard Base (LSB,
  available at <ulink url="http://www.linuxbase.org"/>) recommends only
  that, besides the group <quote>root</quote> with a Group ID (GID) of 0,
  a group <quote>bin</quote> 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 os="j">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 os="k"><userinput>touch ${CLFS}/var/run/utmp ${CLFS}/var/log/{btmp,lastlog,wtmp}
chmod -v 664 ${CLFS}/var/run/utmp ${CLFS}/var/log/lastlog
chmod -v 600 ${CLFS}/var/log/btmp</userinput></screen>

  <para os="l">The <filename>/var/run/utmp</filename> file records the users
  that are currently logged in. 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/btmp</filename> file
  records the bad login attempts.</para>

</sect1>