lfs-book/chapter08/fstab.xml

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

  <title>Creating the /etc/fstab File</title>

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

  <para>The <filename>/etc/fstab</filename> file is used by some programs to
  determine where file systems are to be mounted by default, in which order, and
  which must be checked (for integrity errors) prior to mounting. Create a new
  file systems table like this:</para>

<screen><userinput>cat &gt; /etc/fstab &lt;&lt; "EOF"
<literal># Begin /etc/fstab

# file system  mount-point  type   options         dump  fsck
#                                                        order

/dev/<replaceable>&lt;xxx&gt;</replaceable>     /            <replaceable>&lt;fff&gt;</replaceable>  defaults        1     1
/dev/<replaceable>&lt;yyy&gt;</replaceable>     swap         swap   pri=1           0     0
proc           /proc        proc   defaults        0     0
sysfs          /sys         sysfs  defaults        0     0
devpts         /dev/pts     devpts gid=4,mode=620  0     0
tmpfs          /dev/shm     tmpfs  defaults        0     0
# End /etc/fstab</literal>
EOF</userinput></screen>

  <para>Replace <replaceable>&lt;xxx&gt;</replaceable>,
  <replaceable>&lt;yyy&gt;</replaceable>, and <replaceable>&lt;fff&gt;</replaceable>
  with the values appropriate for the system, for example, <filename
  class="partition">hda2</filename>, <filename
  class="partition">hda5</filename>, and <systemitem
  class="filesystem">ext3</systemitem>. For details on the six
  fields in this file, see <command>man 5 fstab</command>.</para>

  <para>The <filename class="directory">/dev/shm</filename> mount point
  for <systemitem class="filesystem">tmpfs</systemitem> is included to
  allow enabling POSIX-shared memory. The kernel must have the required
  support built into it for this to work (more about this is in the next
  section). Please note that very little software currently uses
  POSIX-shared memory.  Therefore, consider the <filename
  class="directory">/dev/shm</filename> mount point optional. For more
  information, see
  <filename>Documentation/filesystems/tmpfs.txt</filename> in the kernel
  source tree.</para>

  <para>Filesystems with MS-DOS or Windows origin (i.e.: vfat, ntfs, smbfs, cifs,
  iso9660, udf) need the <quote>iocharset</quote> mount option in order for
  non-ASCII characters in file names to be interpreted properly. The value
  of this option should be the same as the character set of your locale,
  adjusted in such a way that the kernel understands it. This works if the
  relevant character set definition (found under File systems -&gt;
  Native Language Support) has been compiled into the kernel
  or built as a module. The <quote>codepage</quote> option is also needed for
  vfat and smbfs filesystems. It should be set to the codepage number used
  under MS-DOS in your country. E.g., in order to mount USB flash drives, a
  ru_RU.KOI8-R user would need the following in the options portion of its
  mount line in <filename>/etc/fstab</filename>:</para>

<screen><literal>noauto,user,quiet,showexec,iocharset=koi8r,codepage=866</literal></screen>

  <para>The corresponding options fragment for ru_RU.UTF-8 users is:</para>

<screen><literal>noauto,user,quiet,showexec,iocharset=utf8,codepage=866</literal></screen>

  <note>
    <para>In the latter case, the kernel emits the following message:</para>

<screen><computeroutput>FAT: utf8 is not a recommended IO charset for FAT filesystems,
    filesystem will be case sensitive!</computeroutput></screen>

    <para>This negative recommendation should be ignored, since all other values
    of the <quote>iocharset</quote> option result in wrong display of filenames in
    UTF-8 locales.</para>
  </note>

  <para>It is also possible to specify default codepage and iocharset values for
  some filesystems during kernel configuration. The relevant parameters
  are named
  <quote>Default NLS Option</quote> (<option>CONFIG_NLS_DEFAULT)</option>,
  <quote>Default Remote NLS Option</quote> (<option>CONFIG_SMB_NLS_DEFAULT</option>),
  <quote>Default codepage for FAT</quote> (<option>CONFIG_FAT_DEFAULT_CODEPAGE</option>), and
  <quote>Default iocharset for FAT</quote> (<option>CONFIG_FAT_DEFAULT_IOCHARSET</option>).
  There is no way to specify these settings for the
  ntfs filesystem at kernel compilation time.</para>
  <!-- Personally, I find it more foolproof to always specify the iocharset and
  codepage in /etc/fstab for MS-based filesystems - Alexander E. Patrakov -->

  <para>It is possible to make the ext3 filesystem reliable across power
  failures for some hard disk types.  To do this, add the
  <option>barrier=1</option> mount option to the appropriate entry in
  <filename>/etc/fstab</filename>.  To check if the disk drive supports
  this option, run 
  <ulink url="http://www.linuxfromscratch.org/blfs/view/cvs/general/hdparm.html">hdparm</ulink>
  on the applicable disk drive.  For example, if:</para>

<screen role="nodump"><userinput>hdparm -I /dev/sda | grep NCQ</userinput></screen>

  <para>returns non-empty output, the option is supported.</para>

  <para>Note: Logical Volume Management (LVM) based partitions cannot use the
  <option>barrier</option> option.</para>

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