<sect1 id="scripts-bash-environment">

    <title>Environment Variables</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 

        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 <command>centos-art.sh</command> script

        environment. This environment inherits all variables from the

        user environment and contains the variables and

        functionalities defined by the

        <command>centos-art.sh</command> script. 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 of <command>centos-art.sh</command>

        script but the user environment only. However, if your

        interest is improving the <command>centos-art.sh</command>

        script somehow, to know the <command>centos-art.sh</command>

        script environment is a fundamental knowledge you need to have

        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 <command>centos-art.sh</command> script environment</title>

    <screenshot>

    <screeninfo>The <command>centos-art.sh</command> script environment</screeninfo>

    <mediaobject>

    <textobject>

<programlisting>

---------------------------------------------------

User environment

----|-------------------|--------------------------

.   |-- TCAR_WORKDIR    |-- EDITOR                .

.   |-- LANG            |-- HOME                  .

.   `-- centos-art.sh   `-- ...                   .

.       ----|------------------------------------ .

.       centos-art.sh environment                 .

.       ----|-----------------|------------------ .

.       .   |-- CLI_NAME      |-- render()      . .

.       .   |-- CLI_BASEDIR   |   |-- svg()     . .

.       .   |-- CLI_TEMPDIR   |   `-- docbook() . .

.       .   |-- CLI_VERSION   |-- help()        . .

.       .   `-- ...           `-- ...           . .

.       ......................................... .

...................................................

</programlisting>

    </textobject>

    </mediaobject>

    </screenshot>

    </example>

    <para>

        To study the environment of <command>centos-art.sh</command>

        script consider the directory structure under 

        class="directory">trunk/Scripts/Bash/</filename>. In this

        structure each directory under 

        class="directory">Functions</filename> creates a new function

        environment inside the <command>centos-art.sh</command> script

        environment. You can only execute one function by script

        execution so it will only be one function environment inside

        the <command>centos-art.sh</command> script environment every

        time it is executed. In some cases, it is possible to find a

        sub-function environment which takes place inside the function

        environment.  This is the case of the

        <function>render</function> functionality which produces both

        images and docbook manuals. Likewise function environments to

        <command>centos-art.sh</command> script environment, there can

        only exist one sub-function environment inside the current

        function environment.

    </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 

        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 

        class="directory">/usr/bin/vim</filename> text editor, the one

        installed by default in &TC;;. 

    </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 &TC;;,

        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 uses 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

        &TC;; 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 &TC;; 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 tzset(3) manual page.  

    </para>

    </sect3>

    </sect2>

</sect1>