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

    <title>Script Execution Environment</title>

    <para>
        The execution environment of <command>centos-art.sh</command>
        script can be defined as the virtual boundery of memory in
        which the script does what it was conceived to do once
        executed by a command-line interpreter (e.g., Bash). When you
        execute the <command>centos-art.sh</command> script in your
        terminal, the interpreter behind it creates a new execution
        environment for it which inherits all the variables and
        functions set in the shell execution environment and those
        exported to it through the
        <filename>~/.bash_profile</filename> file, as well.
    </para>

    <para>
        The <command>centos-art.sh</command> script uses the
        <filename>~/.bash_profile</filename> file to implement
        per-user customizations.  For example, you can use this file
        to set the location of your working copy through the
        <envar>TCAR_WORKDIR</envar> enviroment variable. By default
        this variable is set to <filename
        class="directory">${HOME}/artwork</filename>, but you can
        reset to something different to fit your needs. See <xref
        linkend="repo-ws-config-ChangeWorkingCopy" />.
    </para>

    <para>
        Once the <command>centos-art.sh</command> script has been
        executed, it creates different levels of execution
        environments inside the one created by the script itself on
        the shell.  These different environment levels can be seen as
        a tree of execution environments which inherit one another, as
        illustrated in <xref
        linkend="scripts-bash-environments-example1" />.  These
        different levels of execution evironments are where the
        <command>centos-art.sh</command> script is developed in.
    </para>

    <example id="scripts-bash-environments-example1">
    <title>The execution environment</title>
    <screenshot>
    <screeninfo>The execution environment</screeninfo>
    <mediaobject>
    <textobject>
<programlisting>
---------------------------------------------------------------
Shell execution environment
----|-------------------|-----------------|--------------------
.   |-- TCAR_WORKDIR    |-- TCAR_BRAND    |-- EDITOR          .
.   |-- LANG            |-- HOME          |-- PATH            .
.   `-- centos-art.sh   `-- ...           `-- ...             .
.       ----|------------------------------------------------ .
.       centos-art.sh script execution environment            .
.       ----|--------------------|--------------------------- .
.       .   |-- CLI_NAME         `-- cli()                  . .
.       .   |-- CLI_VERSION          |-- render()           . .
.       .   |-- CLI_BASEDIR          |   |-- svg()          . .
.       .   |-- CLI_FUNCDIR          |   `-- docbook()      . .
.       .   |-- TMPDIR               |-- help()             . .
.       .   `-- ...                  |   |-- docbook()      . .
.       .                            |   `-- texinfo()      . .
.       .                            |-- locale()           . .
.       .                            |-- cli_printMessage() . .
.       .                            |-- cli_getFilesList() . .
.       .                            `-- ...                . .
.       ..................................................... .
...............................................................
</programlisting>
    </textobject>
    </mediaobject>
    </screenshot>
    </example>

    <para>
        The first file the <command>centos-art.sh</command> script
        calls is the
        <filename>Scripts/Bash/Functions/Common/cli.sh</filename>
        file. This file initializes variables and functions can be
        used along the script execution environment lifetime.  Such
        environment variables are for internal use inside the
        <command>centos-art.sh</command> script only and users
        shouldn't modify them to customize the script in a per-user
        level.  Instead, to customize the script behaviour in a
        per-user level, users need to make use of environment
        variables set in <filename>~/.bash_profile</filename> file.
    </para>

    <sect2 id="scripts-bash-environment-varref">

    <title>Environment Variables</title>

    <para>
        The <command>centos-art.sh</command> script uses the following
        system environment variables:
    </para>

    <variablelist>
    <varlistentry>
    <term><envar>PATH</envar></term>
    <listitem>
    <para>
        The <envar>PATH</envar> environment variable is specific to
        the operating system and provides search paths for command
        execution.  By default, the centos-art.sh script links
        executable scripts from the <filename
        class="directory">~/bin</filename> directory which is one of
        the locations used as search path in this variable. This is
        how we create the <command>centos-art</command> command from
        the <command>centos-art.sh</command> script  inside your
        working copy.
    </para>

    <para>
        This variable is not initialized inside the
        <command>centos-art.sh</command> script. Instead, the value
        set in <filename>~/.bash_profile</filename> file is used. 
    </para>

    </listitem>
    </varlistentry>

    <varlistentry>
    <term><envar>EDITOR</envar></term>
    <listitem>
    <para>
        The <envar>EDITOR</envar> environment variable is specific to
        the operating system and provides the path to your default
        text editor. 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>
        Possible values for this variable are:
    </para>

    <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>
        In case none of these values is set for the
        <envar>EDITOR</envar> environment variable inside
        <filename>~/.bash_profile</filename>, the
        <command>centos-art.sh</command> script uses <filename
        class="directory">/usr/bin/vim</filename> as default text
        editor. This is the default text editor installed by default
        in &TCD;. 
    </para>

    </listitem>
    </varlistentry>
    <varlistentry>
    <term><varname>TEXTDOMAIN</varname></term>
    <listitem>
    <para>
        The <envar>TEXTDOMAIN</envar> environment variable is specific
        to the operating system and provides the domain name of that
        application we are producing translation messages for. This
        variable, in combination with <envar>TEXTDOMAINDIR</envar>, is
        used by <application>gettext</application> to find out the
        location of translation messages.  In the very specific case
        of <command>centos-art.sh</command> script we use the
        <literal>centos-art.sh</literal> name as domain name.
    </para>
    
    <para>
        This variable is initialized inside the
        <command>centos-art.sh</command> script, so if you set it
        outside it (e.g., in <filename>~/.bash_profile</filename>) the
        value you set there will be overwritten by that one set inside
        <command>centos-art.sh</command> script, once it is executed.
    </para>
    </listitem>
    </varlistentry>

    <varlistentry>
    <term><varname>TEXTDOMAINDIR</varname></term>
    <listitem>
    <para>
        The <envar>TEXTDOMAINDIR</envar> environment variable is
        specific to the operating system and provides the absolute
        path to the directory containing the translation messages
        related to that application specified by
        <envar>TEXTDOMAIN</envar> environment variable.  In the very
        specific case of <command>centos-art.sh</command> script we
        use the <filename
        class="directory">Locales/Scripts/Bash</filename>
        path as default value.
    </para>
    <para>
        This variable is initialized inside the
        <command>centos-art.sh</command> script, so if you set it
        outside it (e.g., in <filename>~/.bash_profile</filename>) the
        value you set there will be overwritten by that one set inside
        <command>centos-art.sh</command> script, once it is executed.
    </para>
    </listitem>
    </varlistentry>

    <varlistentry>
    <term><envar>TMPDIR</envar></term>
    <listitem>
    <para>
        The <envar>TMPDIR</envar> environment variable is specific to
        the operating system and provides the absolute path to the
        temporal directory the centos-art.sh script will use along its
        execution. This variable is defined inside the
        <command>centos-art.sh</command> script itself using the
        <command>mktemp</command> command and will be unique on each
        script execution. Thus, you should be able to run several
        instances of <command>centos-art.sh</command> script
        simultaneously without any problem. 
    </para>
    
    <para>
        Each time you need to store temporal files, do it inside the
        absolute path specified by this variable.
    </para>

    <para>
        This variable is initialized inside the
        <command>centos-art.sh</command> script, so if you set it
        outside it (e.g., in <filename>~/.bash_profile</filename>) the
        value you set there will be overwritten by that one set inside
        <command>centos-art.sh</command> script, once it is executed.
    </para>
    </listitem>
    </varlistentry>

    <varlistentry>
    <term><envar>LANG</envar></term>
    <listitem>
    <para>
        The <envar>LANG</envar> environment variable is specific to
        the operating system and controls the default locale
        information of it.  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>
        
    <para>
        The <envar>LANG</envar> environment 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, or even
        resetting the variable before executing the
        <command>centos-art.sh</command> script.
    </para>
    </listitem>
    </varlistentry>

    </variablelist>

    <para>
        In addition to system environment variables described above,
        the <command>centos-art.sh</command> script adds the following
        variables inside the <filename>~/.bash_profile</filename> file
        to control the script behaviour in a per-user level:
    </para>

    <variablelist>
    <varlistentry>
    <term><varname>TCAR_WORKDIR</varname></term>
    <listitem>
    <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. In order for this variable to be customizable you
        need to configure your workstation first, as described in
        <xref linkend="repo-ws-config" />.
    </para>
    <para>
        By default, when this variable is not set, the
        <command>centos-art.sh</command> script assumes the <filename
        class="directory">${HOME}/artwork</filename> path as default
        location for your working copy.
    </para>
    </listitem>
    </varlistentry>

    <varlistentry>
    <term><varname>TCAR_BRAND</varname></term>
    <listitem>
    <para>
        The <envar>TCAR_BRAND</envar> environment variable is specific
        to <command>centos-art.sh</command> script and controls the
        brand information that identifies the content produced inside
        &TCAR;. The brand information is used to give name to some
        files inside the repository (e.g., see files under <filename
        class="directory">Identity/Models/Brands</filename>
        directory).
    </para>
    <para>
        By default, this variable takes <literal>centos</literal> as
        value. In case you want to change it to something else, you
        should consider the following implications:
    </para>
    <itemizedlist>
    <listitem>
    <para>
        The <command>centos-art.sh</command> script will no longer be
        referred as such. Instead, the
        <filename>${TCAR_BRAND}-art.sh</filename> name will be used.
        This implies that you no longer are using the
        <command>centos-art.sh</command> file we provide as part of
        &TCAR; and won't be able to commit changes to it. However, if
        you retain the same logic from
        <command>centos-art.sh</command> script in
        <filename>${TCAR_WORKDIR}-art.sh</filename>, you can use
        common and specific functionalities provided by
        <command>centos-art.sh</command> script and commit changes to
        them.
    </para>
    </listitem>
    <listitem>
    <para>
        The files stored under <filename
        class="directory">Identity/Models/Brands</filename>
        should be named using the value of
        <literal>${TCAR_BRAND}</literal> as sect2. If you change
        the value of this variable, you need to be sure the new value
        set does coincide with the file names you use to store brand
        information.
    </para>
    </listitem>
    </itemizedlist>
    </listitem>
    </varlistentry>
    </variablelist>

    </sect2>

    <sect2 id="scripts-bash-environment-func">

    <title>Environment Functions</title>

    <para>
        Once environment variables are initialized, the
        <command>centos-art.sh</command> script initializes common and
        specific environment functions.
    </para>
    
    <para>
        Common environment functions are stored under <filename
        class="directory">Scripts/Bash/Functions/Commons</filename>
        directory and will be available always, both for common
        environment functions themselves and specific environment
        functions.
    </para>

    <para>
        Specific environment functionalities, on the other hand, are
        stored in the <filename
        class="directory">Scripts/Bash/Functions/${CLI_FUNCDIRNAM}/${CLI_FUNCNAME}.sh</filename>
        file, where <varname>CLI_FUNCDIRNAME</varname> is the first
        argument passed to centos-art.sh script with the first letter
        in uppercase but the rest in lowercase and
        <varname>CLI_FUNCNAME</varname> is the first argument passed
        to centos-art.sh script with all letters in lowercase.
        Specific functionalities are exported after common
        functionalities, so specific environment functionalities
        aren't available inside common environment functionalities.
    </para>

    <para>
        In <xref linkend="scripts-bash-environments-example1" />,
        <function>render</function>, <function>help</function> and
        <function>locale</function> are all specific environment
        functions while <function>cli_printMessage</function> and
        <function>cli_getFilesList</function> are common environment
        functions.
    </para>

    <para>
        Both specific and common environment functions exist to
        standardize frequent tasks inside &TCAR;. The following
        sect2s will describe which these frequent tasks are and the
        way they are standardized using specific and common
        environment functions.
    </para>

    </sect2>

</sect1>