<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>