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>First make the mount points for these filesystems:</para>
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13 |
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14 | <screen><userinput>mkdir -p $LFS/{proc,dev/pts}</userinput></screen>
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15 |
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16 | <para>Now become <emphasis>root</emphasis>, since only
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17 | <emphasis>root</emphasis> can mount file systems in unusual places. Then
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18 | check again that the LFS environment variable is set correctly by running
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19 | <userinput>echo $LFS</userinput> and making sure it shows the path to your LFS
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20 | partition's mount point, which is <filename
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21 | class="directory">/mnt/lfs</filename> if you followed our example.</para>
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22 |
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23 | <para>The <emphasis>proc</emphasis> file system is the process information
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24 | pseudo file system through which the kernel provides information about the
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25 | status of the system. Mount it with:</para>
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26 |
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27 | <screen><userinput>mount proc $LFS/proc -t proc</userinput></screen>
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28 |
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29 | <para>The <emphasis>devpts</emphasis> file system is now the most common way
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30 | for pseudo terminals (PTYs) to be implemented. Mount it with:</para>
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31 |
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32 | <screen><userinput>mount devpts $LFS/dev/pts -t devpts</userinput></screen>
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33 |
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34 | <para>This last command might fail with an error to the effect of:</para>
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35 |
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36 | <blockquote><screen>filesystem devpts not supported by kernel</screen></blockquote>
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37 |
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38 | <para>The most likely cause for this is that your host system's kernel was
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39 | compiled without support for the devpts file system. You can check which file
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40 | systems your kernel supports by peeking into its internals with
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41 | <command>cat /proc/filesystems</command>. If a file system type named
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42 | <emphasis>devfs</emphasis> is listed there, then we'll be able to work around
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43 | the problem by mounting the host's devfs file system on top of the new
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44 | <filename>/dev</filename> structure which we'll create later on in the section
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45 | on <xref linkend="ch-system-MAKEDEV"/>. If devfs was not listed, do not worry
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46 | because there is yet a third way to get PTYs working inside the chroot
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47 | environment. We'll cover this shortly in the aforementioned
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48 | <xref linkend="ch-system-MAKEDEV"/> section.</para>
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49 |
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50 | <para>Remember, if for any reason you stop working on your LFS, and start again
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51 | later, it's important to check that these file systems are mounted again before
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52 | entering the chroot environment, otherwise some problems could occur.</para>
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53 |
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54 | </sect1>
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55 |
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