<sect1 id="scripts-bash-environment">
 
    <title>Execution Environment</title>
 
    <para>
        When you login in your computer you enter into a unique user
        environment which you can customize by setting environment
        variables in the <filename>~/.bash_profile</filename>
        file.<footnote><para>To know more about environment variables,
        see the bash(1) man page.</para></footnote> This way different
        users can benefit from their own environment variables to
        customize the execution of <command>centos-art.sh</command>
        script in a safe way.  For example, users can use the
        variables of their environments to set different locations for
        their working copies of &TCAR;.<footnote><para>See <xref
        linkend="repo-ws-config-ChangeWorkingCopy"
        /></para></footnote>
    </para>
 
    <para>
        When you execute the <command>centos-art.sh</command> script,
        you create a new environment inside the user environment which
        we call the script environment. This environment inherits all
        variables from the user environment and contains the variables
        and functionalities defined by the script itself. If your only
        interest is using the <command>centos-art.sh</command> script
        to accomplish tasks inside the working copy, you don't need to
        know the whole environment it uses, but the user environment
        only. However, if your interest is improving it somehow, to
        know the environment where it is run is a fundamental
        knowledge you need to be armed with in order to understand
        where to put the code you want to contribute inside the
        script.
    </para>
 
    <example id="scripts-bash-environment-1">
    <title>The script environment</title>
    <screenshot>
    <screeninfo>The script environment</screeninfo>
    <mediaobject>
    <textobject>
<programlisting>
-------------------------------------------------------
User environment
----|-------------------|------------------------------
.   |-- TCAR_WORKDIR    |-- EDITOR                    .
.   |-- LANG            |-- HOME                      .
.   `-- centos-art.sh   `-- ...                       .
.       ----|---------------------------------------- .
.       centos-art.sh script environment              .
.       ----|-----------------|---------------------- .
.       .   |-- CLI_NAME      `-- init()            . .
.       .   |-- CLI_VERSION       |-- render()      . .
.       .   |-- CLI_BASEDIR       |   |-- svg()     . .
.       .   |-- CLI_FUNCDIR       |   `-- docbook() . .
.       .   |-- CLI_TEMPDIR       |-- help()        . .
.       .   `-- ...               |   |-- docbook() . .
.       .                         |   `-- texinfo() . .
.       .                         |-- locale()      . .
.       .                         `-- ...           . .
.       ............................................. .
.......................................................
</programlisting>
    </textobject>
    </mediaobject>
    </screenshot>
    </example>
 
    <para>
        To study the environment of <command>centos-art.sh</command>
        script, you need to consider the directory structure under
        <filename class="directory">trunk/Scripts/Bash/</filename>. In
        this structure each directory under <filename
        class="directory">Functions/</filename> creates a new function
        environment inside the script environment. You can only
        execute one function environment at a time for each script
        environment. In some cases, it is possible to find a
        sub-function environment which takes place inside the function
        environment.  Such is the case of the
        <function>render</function> functionality which produces both
        images and DocBook manuals.
    </para>
    
    <note>
    <para>
        If you need more environment levels from sub-function
        environment on, then it is a good time for you to consider the
        creation of a new function environment at all.
    </para>
    </note>
 
    <sect2>
    <title>User's Profile (<filename>~/.bash_profile</filename>)</title>
 
    <sect3>
    <title>Default working copy</title>
    <screen>TCAR_WORKDIR=${HOME}/artwork</screen>
    <para>
        The <envar>TCAR_WORKDIR</envar> environment variable is
        specific to <command>centos-art.sh</command> script and
        controls the working copy default location in the workstation.
        This variable doesn't exist just after installing your
        workstation. This variable appears inside the
        <filename>~/.bash_profile</filename> file (and so in the user
        environment of yours) after configuring your workstation, as
        described in <xref linkend="repo-ws-config" />.
    </para>
 
    </sect3>
 
    <sect3>
    <title>Default execution path</title>
    <screen>PATH=$PATH:$HOME/bin</screen>
    <para>
        This is the location where we store links to executable files
        inside the working copy.
    </para>
    </sect3>
 
    <sect3>
    <title>Default text editor</title>
    <screen>EDITOR=/usr/bin/vim</screen>
    <para>
        The default text editor information is controlled by the
        <envar>EDITOR</envar> environment variable. The
        <command>centos-art.sh</command> script uses the default text
        editor to edit subversion pre-commit messages, translation
        files, documentation files, script files, and similar
        text-based files.
    </para>
 
    <para>
        If <envar>EDITOR</envar> environment variable is not set,
        <command>centos-art.sh</command> script uses <filename
        class="directory">/usr/bin/vim</filename> as default text
        editor. Otherwise, the following values are recognized by
        <command>centos-art.sh</command> script:
 
        <itemizedlist>
        <listitem>
        <para>
            <filename class="directory">/usr/bin/vim</filename>
        </para>
        </listitem>
 
        <listitem>
        <para>
        <filename class="directory">/usr/bin/emacs</filename>
        </para>
        </listitem>
 
        <listitem>
        <para>
            <filename class="directory">/usr/bin/nano</filename>
        </para>
        </listitem>
        </itemizedlist>
 
    </para>
 
    <para>
        If none of these values is set in the <envar>EDITOR</envar>
        environment variable, the <command>centos-art.sh</command>
        script uses <filename
        class="directory">/usr/bin/vim</filename> text editor, the one
        installed by default in &TCD;. 
    </para>
    </sect3>
 
    <sect3>
    <title>Default locale information</title>
    <para>
        The default locale information is controlled by the
        <envar>LANG</envar> environment variable. This variable is
        initially set in the installation process of &TCD;,
        specifically in the <emphasis>Language</emphasis> step.
        Generally, there is no need to customize this variable in your
        personal profile. If you need to change the value of this
        environment variable do it through the login screen of GNOME
        Desktop Environment or the
        <command>system-config-language</command> command.
    </para>
 
    <para>
        The <command>centos-art.sh</command> script use the
        <envar>LANG</envar> environment variable to determine what
        language to use for printing output messages from the script
        itself, as well as the portable objects locations that need to
        be updated or edited when you localize directory structures
        inside the working copy of &TCAR;.
    </para>
    </sect3>
 
    <sect3>
    <title>Default time zone representation</title>
    <para>
        The time zone representation is a time correction applied to
        the system time (stored in the BIOS clock) based on your
        country location.  This correction is specially useful to
        distributed computers around the world that work together and
        need to be syncronized in time to know when things happened.
    </para>
    <para>
        &TCAR; is made of one server and several workstations spread
        around the world. In order for all these workstations to know
        when changes in the server took place, it is required that
        they all set their system clocks to use the same time
        information (e.g., through UTC (Coordinated Universal Time))
        and set the time correction for their specific countries in
        the operating system.  Otherwise, it would be difficult to
        know when something exactly happened.
    </para>
 
    <para>
        Generally, setting the time zone information is a
        straight-forward task and configuration tools provided by
        &TCD; do cover time correction for most of the countries
        around the world, thus we don't include it to your personal
        profile.
    </para>
 
    <para>
        In case you need a time precision not provided by any of the
        date and time configuration tools provided by &TCD; then, you
        need to customize the <envar>TZ</envar> environment variable
        in your personal profile to correct the time information by
        yourself.  The format of <envar>TZ</envar> environment
        variable is described in <code>tzset(3)</code> manual page.  
    </para>
    </sect3>
 
    </sect2>
 
</sect1>