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|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML
><HEAD
><TITLE
>Hardware Utilities </TITLE
><META
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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="HWUTILS"
></A
>4.1. Hardware Utilities</H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MAKEDEV"
></A
>4.1.1. The <B
CLASS="COMMAND"
>MAKEDEV</B
> Script</H2
><P
>Most device files will already be created and will be there
ready to use after you install your Linux system. If by some chance
you need to create one which is not provided then you should first
try to use the <B
CLASS="COMMAND"
>MAKEDEV</B
> script. This script is
usually located in <TT
CLASS="FILENAME"
>/dev/MAKEDEV</TT
> but might also
have a copy (or a symbolic link) in
<TT
CLASS="FILENAME"
>/sbin/MAKEDEV</TT
>. If it turns out not to be in
your path then you will need to specify the path to it
explicitly.</P
><P
>In general the command is used as:
<TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
> <TT
CLASS="PROMPT"
>#</TT
> <TT
CLASS="USERINPUT"
><B
>/dev/MAKEDEV -v ttyS0</B
></TT
>
<TT
CLASS="COMPUTEROUTPUT"
>create ttyS0 c 4 64 root:dialout 0660</TT
>
</PRE
></FONT
></TD
></TR
></TABLE
>
This will create the device file <TT
CLASS="FILENAME"
>/dev/ttyS0</TT
>
with major node 4 and minor node 64 as a character device with
access permissions 0660 with owner root and group dialout.</P
><P
><TT
CLASS="FILENAME"
>ttyS0</TT
> is a serial port. The major and
minor node numbers are numbers understood by the kernel. The kernel
refers to hardware devices as numbers, this would be very difficult
for us to remember, so we use filenames. Access permissions of 0660
means read and write permission for the owner (root in this case)
and read and write permission for members of the group (dialout in
this case) with no access for anyone else.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MKNOD"
></A
>4.1.2. The <B
CLASS="COMMAND"
>mknod</B
> command</H2
><P
><B
CLASS="COMMAND"
>MAKEDEV</B
> is the preferred way of creating
device files which are not present. However sometimes the
<B
CLASS="COMMAND"
>MAKEDEV</B
> script will not know about the device
file you wish to create. This is where the <B
CLASS="COMMAND"
>mknod</B
>
command comes in. In order to use <B
CLASS="COMMAND"
>mknod</B
> you need
to know the major and minor node numbers for the device you wish to
create. The <TT
CLASS="FILENAME"
>devices.txt</TT
> file in the kernel
source documentation is the canonical source of this
information.</P
><P
>To take an example, let us suppose that our version of the
<B
CLASS="COMMAND"
>MAKEDEV</B
> script does not know how to create the
<TT
CLASS="FILENAME"
>/dev/ttyS0</TT
> device file. We need
to use <B
CLASS="COMMAND"
>mknod</B
> to create it. We know from looking at the
<TT
CLASS="FILENAME"
>devices.txt</TT
> that it should be a character
device with major number 4 and minor number 64. So we now know all
we need to create the file.
<TABLE
BORDER="1"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="SCREEN"
> <TT
CLASS="PROMPT"
>#</TT
> <TT
CLASS="USERINPUT"
><B
>mknod /dev/ttyS0 c 4 64</B
></TT
>
<TT
CLASS="PROMPT"
>#</TT
> <TT
CLASS="USERINPUT"
><B
>chown root.dialout /dev/ttyS0</B
></TT
>
<TT
CLASS="PROMPT"
>#</TT
> <TT
CLASS="USERINPUT"
><B
>chmod 0644 /dev/ttyS0</B
></TT
>
<TT
CLASS="PROMPT"
>#</TT
> <TT
CLASS="USERINPUT"
><B
>ls -l /dev/ttyS0</B
></TT
>
<TT
CLASS="COMPUTEROUTPUT"
> crw-rw---- 1 root dialout 4, 64 Oct 23 18:23 /dev/ttyS0
</TT
>
</PRE
></FONT
></TD
></TR
></TABLE
>
As you can see, many more steps are required to create the file. In
this example you can see the process required however. It is
unlikely in the extreme that the ttyS0 file would not be provided by
the <B
CLASS="COMMAND"
>MAKEDEV</B
> script, but it suffices to illustrate
the point.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="LSPCI"
></A
>4.1.3. The <B
CLASS="COMMAND"
>lspci</B
> command</H2
><P
>lspci</P
><P
>TO BE ADDED</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="LSDEV"
></A
>4.1.4. The <B
CLASS="COMMAND"
>lsdev</B
> command</H2
><P
>lsdev</P
><P
>TO BE ADDED</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="LSUSB"
></A
>4.1.5. The <B
CLASS="COMMAND"
>lsusb</B
> command</H2
><P
>lsusb</P
><P
>TO BE ADDED</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="LSRAID"
></A
>4.1.6. The <B
CLASS="COMMAND"
>lsraid</B
> command</H2
><P
>lsraid</P
><P
>TO BE ADDED</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="HDPARM"
></A
>4.1.7. The <B
CLASS="COMMAND"
>hdparm</B
> command</H2
><P
>hdparm</P
><P
>TO BE ADDED</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MORE-HWRESOURCES"
></A
>4.1.8. More Hardware Resources</H2
><P
>More information on what hardware resources the kernel is using
can be found in the <TT
CLASS="FILENAME"
>/proc</TT
> directory. Refer to
<A
HREF="proc-fs.html"
>Section 3.7</A
> in chapter 3.
</P
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