src/docbkx/shell.xml

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    <title>The HBase Shell</title>

    <para>
        The HBase Shell is <link xlink:href="http://jruby.org">(J)Ruby</link>'s
        IRB with some HBase particular commands added.  Anything you can do in
        IRB, you should be able to do in the HBase Shell.</para>
        <para>To run the HBase shell, 
        do as follows:
        <programlisting>$ ./bin/hbase shell</programlisting>
        </para>
            <para>Type <command>help</command> and then <command>&lt;RETURN&gt;</command>
            to see a listing of shell
            commands and options. Browse at least the paragraphs at the end of
            the help emission for the gist of how variables and command
            arguments are entered into the
            HBase shell; in particular note how table names, rows, and
            columns, etc., must be quoted.</para>
        <para>See <xref linkend="shell_exercises" />
            for example basic shell operation.</para>

    <section xml:id="scripting"><title>Scripting</title>
        <para>For examples scripting HBase, look in the
            HBase <filename>bin</filename> directory.  Look at the files
            that end in <filename>*.rb</filename>.  To run one of these
            files, do as follows:
            <programlisting>$ ./bin/hbase org.jruby.Main PATH_TO_SCRIPT</programlisting>
        </para>
    </section>

    <section xml:id="shell_tricks"><title>Shell Tricks</title>
        <section><title><filename>irbrc</filename></title>
                <para>Create an <filename>.irbrc</filename> file for yourself in your
                    home directory. Add customizations. A useful one is
                    command history so commands are save across Shell invocations:
                    <programlisting>
                        $ more .irbrc
                        require 'irb/ext/save-history'
                        IRB.conf[:SAVE_HISTORY] = 100
                        IRB.conf[:HISTORY_FILE] = "#{ENV['HOME']}/.irb-save-history"</programlisting>
                See the <application>ruby</application> documentation of
                <filename>.irbrc</filename> to learn about other possible
                confiurations.
                </para>
        </section>
        <section><title>LOG data to timestamp</title>
            <para>
                To convert the date '08/08/16 20:56:29' from an hbase log into a timestamp, do:
                <programlisting>
                    hbase(main):021:0> import java.text.SimpleDateFormat
                    hbase(main):022:0> import java.text.ParsePosition
                    hbase(main):023:0> SimpleDateFormat.new("yy/MM/dd HH:mm:ss").parse("08/08/16 20:56:29", ParsePosition.new(0)).getTime() => 1218920189000</programlisting>
            </para>
            <para>
                To go the other direction:
                <programlisting>
                    hbase(main):021:0> import java.util.Date
                    hbase(main):022:0> Date.new(1218920189000).toString() => "Sat Aug 16 20:56:29 UTC 2008"</programlisting>
            </para>
            <para>
                To output in a format that is exactly like that of the HBase log format will take a little messing with
                <link xlink:href="http://download.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html">SimpleDateFormat</link>.
            </para>
        </section>
        <section><title>Debug</title>
            <section><title>Shell debug switch</title>
                <para>You can set a debug switch in the shell to see more output
                    -- e.g. more of the stack trace on exception --
                    when you run a command:
                    <programlisting>hbase> debug &lt;RETURN&gt;</programlisting>
                 </para>
            </section>
            <section><title>DEBUG log level</title>
                <para>To enable DEBUG level logging in the shell,
                    launch it with the <command>-d</command> option.
                    <programlisting>$ ./bin/hbase shell -d</programlisting>
               </para>
            </section>
         </section>
    </section>
  </chapter>