| 1 | <sect1 id="ch-system-proc">
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| 2 | <title>Mounting the proc and devpts file systems</title>
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| 3 | <?dbhtml filename="proc.html" dir="chapter06"?>
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| 4 |
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| 5 | <para>In order for certain programs to function properly, the
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| 6 | <emphasis>proc</emphasis> and <emphasis>devpts</emphasis> file systems must be
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| 7 | available within the chroot environment. Since kernel version 2.4 a file system
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| 8 | can be mounted as many times and in as many places as you like, thus it's not a
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| 9 | problem that these file systems are already mounted on your host system --
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| 10 | especially so because they are virtual file systems.</para>
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| 11 |
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| 12 | <para>The <emphasis>proc</emphasis> file system is the process information
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| 13 | pseudo file system through which the kernel provides information about the
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| 14 | status of the system.</para>
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| 15 |
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| 16 | <para>The proc file system is mounted on
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| 17 | <filename class="directory">/proc</filename> by running the following
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| 18 | command:</para>
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| 19 |
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| 20 | <screen><userinput>mount proc /proc -t proc</userinput></screen>
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| 21 |
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| 22 | <para>You might get warning messages from the mount command, such as
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| 23 | these:</para>
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| 24 |
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| 25 | <blockquote><screen>warning: can't open /etc/fstab: No such file or directory
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| 26 | not enough memory</screen></blockquote>
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| 27 |
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| 28 | <para>Ignore these, they're just due to the fact that the system
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| 29 | isn't installed completely yet and some files are missing. The mount itself
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| 30 | will be successful and that's all we care about at this point.</para>
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| 31 |
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| 32 | <para>The <emphasis>devpts</emphasis> file system was mentioned earlier and is
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| 33 | now the most common way for pseudo terminals (PTYs) to be implemented.</para>
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| 34 |
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| 35 | <para>The devpts file system is mounted on
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| 36 | <filename class="directory">/dev/pts</filename> by running:</para>
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| 37 |
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| 38 | <screen><userinput>mount devpts /dev/pts -t devpts</userinput></screen>
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| 39 |
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| 40 | <para>Should this command fail with an error to the effect of:</para>
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| 41 |
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| 42 | <blockquote><screen>filesystem devpts not supported by kernel</screen></blockquote>
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| 43 |
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| 44 | <para>The most likely cause is that your host system's kernel was compiled
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| 45 | without support for the devpts file system. You can check which file systems
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| 46 | your kernel supports by peeking into its internals with a command such as
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| 47 | <userinput>cat /proc/filesystems</userinput>. If a file system type named
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| 48 | <emphasis>devfs</emphasis> is listed there, then we'll be able to work around
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| 49 | the problem by mounting the host's devfs file system on top of the new
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| 50 | <filename>/dev</filename> structure which we'll create later on in the section
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| 51 | on <xref linkend="ch-system-MAKEDEV"/>. If devfs was not listed, do not worry
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| 52 | because there is yet a third way to get PTYs working inside the chroot
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| 53 | environment. We'll cover this shortly in the aforementioned
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| 54 | <xref linkend="ch-system-MAKEDEV"/> section.</para>
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| 55 |
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| 56 | <para>Remember, if for any reason you stop working on your LFS, and start again
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| 57 | later, it's important to check that these file systems are still mounted inside
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| 58 | the chroot environment, otherwise problems are likely to occur.</para>
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| 59 |
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| 60 | </sect1>
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| 61 |
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