<sect1 id="scripts-bash-environment">
<title>The 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>trunk/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">trunk/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">trunk/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">trunk/Identity/Models/Brands</filename>
should be named using the value of
<literal>${TCAR_BRAND}</literal> as sect2. If you change
the value of this variable, you need to be sure the new value
set does coincide with the file names you use to store brand
information.
</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
</variablelist>
</sect2>
<sect2 id="scripts-bash-environment-func">
<title>Environment Functions</title>
<para>
Once environment variables are initialized, the
<command>centos-art.sh</command> script initializes common and
specific environment functions.
</para>
<para>
Common environment functions are stored under <filename
class="directory">trunk/Scripts/Bash/Functions/Commons</filename>
directory and will be available always, both for common
environment functions themselves and specific environment
functions.
</para>
<para>
Specific environment functionalities, on the other hand, are
stored in the <filename
class="directory">trunk/Scripts/Bash/Functions/${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>