@subsection Goals

The @file{trunk/Scripts/Bash/Functions} directory exists to organize

@file{centos-art.sh} specific functionalities.

@subsection Description

The specific functions of @file{centos-art.sh} script are designed

with ``Software Toolbox'' philosophy (@pxref{Toolbox

introduction,,,coreutils.info}) in mind: each program ``should do one

thing well''.  Inside @file{centos-art.sh} script, each specific

functionality is considered a program that should do one thing well.

Of course, if you find that they still don't do it, feel free to

improve them in order for them to do so.

The specific functions of @file{centos-art.sh} script are organized

inside specific directories under @file{trunk/Scripts/Bash/Functions}

location. Each specific function directory should be named as the

function it represents, with the first letter in uppercase. For

example, if the function name is @code{render}, the specific function

directory for it would be @samp{trunk/Scripts/Bash/Functions/Render}.

To better understand how specific functions of @file{centos-art.sh}

script are designed, lets create one function which only goal is to

output different kind of greetings to your screen.

When we create specific functions for @file{centos-art.sh} script it

is crucial to know what these functions will do exactly and if there

is any function that already does what we intend to do. If there is no

one, it is good time to create them then. Otherwise, if

functionalities already available don't do what you exactly expect,

contact their authors and work together to improve them.

@quotation

@strong{Tip} Join CentOS developers mailing list

@email{centos-art@@centos.org} to share your ideas.

@end quotation

It is also worth to know what global functions and variables do we

have available inside @file{centos-art.sh} script, so advantage can be

taken from them. Global variables are defined inside global function

scripts. Global functions scripts are stored immediatly under

@file{trunk/Scripts/Bash/Functions} directory, in files begining with

@samp{cli} prefix.

OK, let's begin with our functionality example.

What function name do we use? Well, lets use @code{greet}. Note that

@samp{hello} word is not a verb; but an expression, a kind of

greeting, an interjection specifically. In contrast, @samp{greet} is a

verb and describes what we do when we say @samp{Hello!}, @samp{Hi!},

and similar expressions.

So far, we've gathered the following function information:

@verbatim

Name: greet

Path: trunk/Scripts/Bash/Functions/Greet

File: trunk/Scripts/Bash/Functions/Greet/greet.sh

@end verbatim

The @file{greet.sh} function script is the first file

@file{centos-art.sh} script loads when the @samp{greet} functionality

is called using commands like @samp{centos-art greet --hello='World'}.

The @file{greet.sh} function script contains the @code{greet} function

definition. 

Inside @file{centos-art.sh} script, as convenction, each function

script has one top commentary, followed by one blank line, and then

one function defintion below it only.

Inside @file{centos-art.sh} script functions, top commentaries have

the following components: the functionality description, one-line for

copyright note with your personal information,  the license under

which the function source code is released ---the @file{centos-art.sh}

script is released as GPL, so do all its functions---, subversion's

@code{$Id$} keyword which is later expanded by @command{svn propset}

command.

In our @code{greet} function example, top commentary for

@file{greet.sh} function script would look like the following:

@verbatim

#!/bin/bash

#

# greet.sh -- This function outputs different kind of greetings to

# your screen. Use this function to understand how centos-art.sh

# script specific functionalities work.

#

# Copyright (C) YEAR YOURFULLNAME

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

# 

# This program is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307

# USA.

# 

# ----------------------------------------------------------------------

# $Id$

# ----------------------------------------------------------------------

@end verbatim

After top commentary, separated by one blank line, the @code{greet}

function definition would look like the following:

@verbatim

function greet {

    # Define global variables.

    # Define command-line interface.

    greet_getActions

}

@end verbatim

The first definition inside @code{greet} function, are global

variables that will be available along @code{greet} function execution

environment. This time we didn't use global variable definitions for

@code{greet} function execution environment, so we left that section

empty.

Later, we call @code{greet_getActions} function to define the

command-line interface of @code{greet} functionality. The @code{greet}

functionality command-line interface defines what and how actions are

performed, based on arguments combination passed to

@file{centos-art.sh} script.

@verbatim

function greet_getActions {

    case "$ACTIONNAM" in

        --hello )

            greet_doHello

            ;;

        --bye )

            greet_doBye

            ;;

        * )

            cli_printMessage "`gettext "The option provided is not valid."`"

            cli_printMessage "$(caller)" 'AsToKnowMoreLine'

    esac

}

@end verbatim

The @var{ACTIONNAM} global variable is defined in @file{cli.sh}

function script and contains the value passed before the equal sign

(i.e., @samp{=}) in the second command-line argument of

@file{centos-art.sh} script. For example, if the second command-line

argument is @option{--hello='World'}, the value of @var{ACTIONNAM}

variable would be @samp{--hello}.  Using this configuration let us

deside which action to perform based on the action name passed to

@file{centos-art.sh} script as second argument. 

The @code{greet} function definition makes available two valid

greetings through @option{--hello} and @option{--bye} options.  If no

one of them is provided as second command-line argument, the @samp{*}

case is evaluated instead. 

The @samp{*} case and its two lines further on should always be

present in @file{_getActions.sh} function scripts, no matter what

specific functionality you are creating. This convenction helps the

user to find out documentation about current functionality in use.  

The @code{greet_doHello} and @code{greet_doBye} function definitions

are the core of @code{greet} specific functionality.  In such function

definitions we set what our @code{greet} function really does: to

output different kinds of greetings.

@verbatim

function greet_doHello {

    cli_printMessage "`gettext "Hello"` $ACTIONVAL"

}

@end verbatim

The @code{greet_doHello} function definition is stored in

@file{greet_doHello.sh} function script. 

@verbatim

function greet_doBye {

    cli_printMessage "`gettext "Goodbye"` $ACTIONVAL"

}

@end verbatim

The @code{greet_doBye} function definition is stored in the

@file{greet_doBye.sh} function script. 

Both @file{greet_doHello.sh} and @file{greet_doBye.sh} function

scripts are stored inside @code{greet}'s function directory path (i.e.

@file{trunk/Scripts/Bash/Functions/Greet}).

The @var{ACTIONVAL} global variable is defined in @file{cli.sh}

function script and contains the value passed after the equal sign

(i.e., @samp{=}) in the second command-line argument of

@file{centos-art.sh} script. For example, if the second command-line

argument is @option{--hello='World'}, the value of @var{ACTIONVAL}

variable would be @samp{World} without quotes.

Let's see how @code{greet} specific functionality files are organzied

under @code{greet}'s function directory. To see file organization we

use the @command{tree} command:

@verbatim

trunk/Scripts/Bash/Functions/Greet

|-- greet_doBye.sh

|-- greet_doHello.sh

|-- greet_getActions.sh

`-- greet.sh

@end verbatim

To try the @code{greet} specific functionality we've just created,

pass the function name (i.e., @samp{greet}) as first argument to

@file{centos-art.sh} script, and any of the valid options as second

argument. Some examples are illustrated below:

@verbatim

[centos@projects ~]$ centos-art greet --hello='World'

Hello World

[centos@projects ~]$ centos-art greet --bye='World'

Goodbye World

[centos@projects ~]$ 

@end verbatim

The word @samp{World} in the examples above can be anything. In fact,

change it to have a little fun.

Now that we have a specific function that works as we expect, it is

time to document it. To document @code{greet} specific functionality,

we use its directory path and the @code{manual} functionality

(@pxref{trunk Scripts Bash Functions Manual}) of @file{centos-art.sh}

script, just as the following command illustrates: 

@verbatim

centos-art manual --edit=trunk/Scripts/Bash/Functions/Greet

@end verbatim

Now that we have documented our function, it is time to translate its

output messages to different languages. To translate specific

functionality output messages to different languages we use the

@code{locale} functionality (@pxref{trunk Scripts Bash Functions

Locale}) of @file{centos-art.sh} script, just as the following command

illustrates:

@verbatim

centos-art locale --edit

@end verbatim

@quotation

@strong{Warning} To translate output messages in different languages,

your system locale information ---as in @env{LANG} environment

variable--- must be set to that locale you want to produce translated

messages for. For example, if you want to produce translated messages

for Spanish language, your system locale information must be set to

@samp{es_ES.UTF-8} or similar.  

@end quotation

Well, it seems that our example is rather complete by now. 

In @code{greet} function example we've described so far, we only use

@command{cli_printMessage} global function in action specific function

definitions in order to print a message simply, but more interesting

things can be achieved inside action specific function definitions.

For example, if you pass a directory path as second argument option

value, you could retrive a list of files from therein, and process

them. If the list of files turns too long or you just want to control

which files to process, you could add the third argument in the form

@option{--filter='regex'} and reduce the amount of files to process

using a regular expression pattern.

The @code{greet} function described in this section may serve you as

an introduction to understand how specific functionalities work inside

@file{centos-art.sh} script. With some of luck this introduction will

also serve you as motivation to create your own @file{centos-art.sh}

script specific functionalities.

By the way, the @code{greet} functionality doesn't exist inside

@file{centos-art.sh} script yet. Would you like to create it?

@subsection Usage

@subsubsection Global variables

The following global variables of @file{centos-art.sh} script, are

available for you to use inside specific functions:

@defvar TEXTDOMAIN

Default domain used to retrieve translated messages. This value is set

in @file{initFunctions.sh} and shouldn't be changed.

@end defvar

@defvar TEXTDOMAINDIR

Default directory used to retrieve translated messages. This value is

set in @file{initFunctions.sh} and shouldn't be changed.

@end defvar

@defvar FUNCNAM

Define function name.

Function names associate sets of actions. There is one set of actions

for each unique function name inside @file{centos-art.sh} script.

Dunction names are passed as first argument in @file{centos-art.sh}

command-line interface. For example, in the command @samp{centos-art

render --entry=path/to/dir --filter=regex}, the @var{ACTION} passed to

@file{centos-art.sh} script is @option{render}.

When first argument is not provided, the @file{centos-art.sh} script

immediatly ends its execution.

@end defvar

@defvar ACTIONNAM

Define action name.

Each action name identifies an specific action to perform, inside an

specific function.

Action name names aare passed as second argument in

@file{centos-art.sh} command-line interface. For example, in the

command @samp{centos-art render --entry=path/to/dir --filter=regex},

the @var{ACTIONNAM} passed to @file{centos-art.sh} script is

@option{--entry}.

When second argument is not provided, the @file{centos-art.sh} script

immediatly ends its execution.

@end defvar

@defvar ACTIONVAL

Define action value.

Action values are associated to just one action name. Action values

contain the repository entry over which its associated action will be

performed in.  Repository entries can be directories, files, or URLs

refering the repository structure.

When action value is not specified as repository entry, the

@file{centos-art.sh} script evaluates the current directory it was

executed from. If such directory is under the repository structure

(i.e., @file{/home/centos/artwork/}), the @file{centos-art.sh} script

uses that directory as value to @var{ACTIONVAL} variable. Otherwise,

if outside the repository structure, the @file{centos-art.sh} script

prints the message @samp{The path provided can't be processed.} and,

after it, immediatly ends script execution.

Default action value is passed as second argument in

@file{centos-art.sh} command-line interface. For example, in the

command @samp{centos-art render --entry=path/to/dir --filter=regex},

the @var{ACTIONVAL} passed to @file{centos-art.sh} script is

@option{path/to/dir}.

@end defvar

@defvar REGEX

Define regular expression used as pattern to build the list of files

to process.

By default, @var{REGEX} variable is set to @code{.+} to match all

files.

Functions that need to build a list of files to process use the option

@option{--filter} to redefine @var{REGEX} variable default value, and

so, control the amount of files to process.

@end defvar

@defvar ARGUMENTS 

Define optional arguments. 

Optional arguments, inside @file{centos-art.sh} script, are considered

as all command-line arguments passed to @file{centos-art.sh} script,

from third argument position on. For example, in the command

@samp{centos-art render --entry=path/to/dir --filter=regex} , the

optional arguments are from @samp{--filter=regex} argument on.

Optional arguments are parsed using @command{getopt} command through

the following base construction: 

@verbatim

# Define short options we want to support.

local ARGSS=""

# Define long options we want to support.

local ARGSL="filter:,to:"

# Parse arguments using getopt(1) command parser.

cli_doParseArguments

# Reset positional parameters using output from (getopt) argument

# parser.

eval set -- "$ARGUMENTS"

# Define action to take for each option passed.

while true; do

    case "$1" in

        --filter )

            REGEX="$2" 

            shift 2

            ;;

        --to )

            TARGET="$2" 

            shift 2

            ;;

        * )

            break

    esac

done

@end verbatim

Optional arguments provide support to command options inside

@file{centos-art.sh} script. For instance, consider the Subversion

(@command{svn}) command, where there are many options (e.g.,

@option{copy}, @option{delete}, @option{move}, etc), and inside each

option there are several modifiers (e.g., @samp{--revision},

@samp{--message}, @samp{--username}, etc.) that can be combined one

another in their short or long variants. 

The @var{ARGUMENTS} variable is used to store arguments passed from

command-line for later use inside @file{centos-art.sh} script. Storing

arguments is specially useful when we want to run a command with some

specific options from them. Consider the following command:

@verbatim

centos-art path --copy=SOURCE --to=TARGET --message="The commit message goes here." --username='johndoe'

@end verbatim

In the above command, the @option{--message}, and @option{--username}

options are specific to @command{svn copy} command. In such cases,

options are not interpreted by @file{centos-art.sh} script itself.

Instead, the @file{centos-art.sh} script uses @command{getopt} to

retrive them and stores them in the @var{ARGUMENT} variable for later

use, as described in the following command:

@verbatim

# Build subversion command to duplicate locations inside the

# workstation.

eval svn copy $SOURCE $TARGET --quiet $ARGUMENTS

@end verbatim

When @command{getopt} parses @var{ARGUMENTS}, we may use short options

(e.g., @option{-m}) or long options (e.g., @option{--message}). When

we use short options, arguments are separated by one space from the

option (e.g., @option{-m 'This is a commit message.'}).  When we use

long options arguments are separated by an equal sign (@samp{=})

(e.g., @option{--message='This is a commit message'}).

In order for @command{getopt} to parse @var{ARGUMENTS} correctly, it

is required to provide the short and long definition of options that

will be passed or at least supported by the command performing the

final action the function script exists for.

As convenction, inside @file{centos-art.sh} script, short option

definitions are set in the @var{ARGSS} variable; and long option

definitions are set in the @var{ARGSL} variable.

When you define short and long options, it may be needed to define

which of these option arguments are required and which not. To define

an option argument as required, you need to set one colon @samp{:}

after the option definition (e.g., @option{-o m: -l message:}).  On

the other hand, to define an option argument as not required, you need

to set two colons @samp{::} after the option definition (e.g.,

@option{-o m:: -l message::}).

@end defvar

@defvar EDITOR 

Default text editor. 

The @file{centos-art.sh} script uses default text @env{EDITOR} to edit

pre-commit subversion messages, translation files, configuration

files, script files, and similar text-based files.

If @env{EDITOR} environment variable is not set, @file{centos-art.sh}

script uses @file{/usr/bin/vim} as default text editor. Otherwise, the

following values are recognized by @file{centos-art.sh} script:

@itemize

@item @file{/usr/bin/vim}

@item @file{/usr/bin/emacs}

@item @file{/usr/bin/nano}

@end itemize

If no one of these values is set in @env{EDITOR} environment variable,

@file{centos-art.sh} uses @file{/usr/bin/vim} text editor by default. 

@end defvar

@subsubsection Functions

Functions defined under @file{trunk/Scripts/Bash/Functions/} directory

are considered global. Global function can be used inside action

specific functionalities and reused inside themselves. This section

provides introductory information to global functions you can use

inside @file{centos-art.sh} script.

@defun cli_commitRepoChanges [LOCATION]

Syncronize changes between repository and working copy.

The @code{cli_commitRepoChanges} function brings changes from the

central repository down to the working copy---using @command{svn

update}---, checks the working copy changes---using @command{svn

status} command---, prints status report---using both @command{svn

update} and @command{svn status} commands output, and finally, commits

recent changes from the working copy up to the repository---using

@command{svn commit} command---.

Previous to commit the working copy changes up to the central

repository, the @code{cli_commitRepoChanges} function asks you to

verify changes---using @command{svn diff} command---, and later,

another confirmation question is shown to be sure you really want to

commit changes up to central repository.

If @var{LOCATION} argument is not specified, the value of

@var{ACTIONVAL} variable is used as reference instead.

@float Figure, trunk/Scripts/Bash/Functions/cli_commitRepoChanges

@verbatim

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

--> Bringing changes from the repository into the working copy

--> Checking changes in the working copy

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

Added           0 file from the repository.

Deleted         0 file from the repository.

Updated         0 file from the repository.

Conflicted      0 file from the repository.

Merged          0 file from the repository.

Modified        4 files from the working copy.

Unversioned     0 file from the working copy.

Deleted         0 file from the working copy.

Added           0 file from the working copy.

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

@end verbatim

@caption{The @code{cli_commitRepoChanges} function output.}

@end float

Call the @code{cli_commitRepoChanges} function before or/and after

calling functions that modify files or directories inside the working

copy as you may need to.  

@end defun

@defun cli_checkFiles FILE [TYPE]

Verify files existence.

@code{cli_checkFiles} receives a @var{FILE} absolute path and performs

file verification as specified in @var{TYPE}.  When @var{TYPE} is not

specified, @code{cli_checkFiles} verifies @var{FILE} existence, no

matter what kind of file it be.  If @var{TYPE} is specified, use one

of the following values:

@table @option

@item d

@itemx directory

Ends script execution if @var{FILE} is not a directory.

When you verify directories with cli_checkFiles, if directory doesn't

exist, @file{centos-art.sh} script asks you for confirmation in order

to create that directory. If you answer positively,

@file{centos-art.sh} script creates that directory and continues

script flows normally. Otherwise, if you answer negatively,

@file{centos-art.sh} ends script execution with an error and

documentation message.

@item f

@item regular-file

Ends script execution if @var{FILE} is not a regular file.

@item h

@itemx symbolic-link

Ends script execution if @var{FILE} is not a symbolic link.

@item x

@itemx execution

Ends script execution if @var{FILE} is not executable.

@item fh

Ends script execution if @var{FILE} is neither a regular file nor a

symbolic link.

@item fd

Ends script execution if @var{FILE} is neither a regular file nor a

directory.

@end table

As default behaviour, if @var{FILE} passes all verifications,

@file{centos-art.sh} script continues with its normal flow. 

@end defun

@defun cli_getCountryCodes [FILTER]

Output country codes supported by @file{centos-art.sh} script. 

The @code{cli_getCountryCodes} function outputs a list with country

codes as defined in ISO3166 standard. When @var{FILTER} is provided,

@code{cli_getCountryCodes} outputs country codes that match

@var{FILTER} regular expression pattern.

@end defun

@defun cli_getCountryName [FILTER]

Outputs country name supported by @file{centos-art.sh} script.

The @code{cli_getCountryName} function reads one language locale code

in the format LL_CC and outputs the name of its related country as in

ISO3166. If filter is specified, @code{cli_getCountryName} returns the

country name that matches the locale code specified in @var{FILTER},

exactly.

@end defun

@defun cli_getCurrentLocale

Output current locale used by @file{centos-art.sh} script. 

The @code{cli_getCurrentLocale} function uses @env{LANG} environment

variable to build a locale pattern that is later applied to

@code{cli_getLocales} function output in order to return the current

locale that @file{centos-art.sh} script works with. 

The current locale information, returned by

@code{cli_getCurrentLocale}, is output from more specific to less

specific. For example, if @samp{en_GB} locale exists in

@code{cli_getLocales} function output, the @samp{en_GB} locale would

take precedence before @samp{en} locale.

Locale precedence selection is quite important in order to define the

locale type we use for message translations. For example, if

@samp{en_GB} is used, we are also saying that the common language

specification for English language (i.e., @samp{en}) is no longer

used. Instead, we are using English non-common country-specific

language specifications like @samp{en_AU}, @samp{en_BW}, @samp{en_GB},

@samp{en_US}, etc., for message translations.  

Use @code{cli_getCurrentLocale} function to know what current locale

information to use inside @file{centos-art.sh} script.

@end defun

@defun cli_getLangCodes [FILTER]

Outputs language codes supported by @file{centos-art.sh} script.

@code{cli_getLangCodes} function outputs a list of language codes as

defined in ISO639 standard. When @var{FILTER} is provided,

@code{cli_getLangCodes} outputs language codes that match @var{FILTER}

regular expression pattern.

@end defun

@defun cli_getLangName [FILTER]

Outputs language names supported by @file{centos-art.sh} script.

@code{cli_getLangName} function reads one language locale code in the

format LL_CC and outputs the language related name as in ISO639. If

filter is specified, @code{cli_getLangName} returns the language name

that matches the locale code specified in @var{FILTER}, exactly.

@end defun

@defun cli_getLocales

Output locale codes supported by @file{centos-art.sh} script.

Occasionally, you use @code{cli_getLocales} function to add locale

information in non-common country-specific language (@samp{LL_CC})

format for those languages (e.g., @samp{bn_IN}, @samp{pt_BR}, etc.)

which locale differences cannot be solved using common language

specifications (@samp{LL}) into one unique common locale specification

(e.g., @samp{bn}, @samp{pt}, etc.).  

@end defun

@defun cli_getRepoName NAME TYPE

Sanitate file names.

Inside @file{centos-art.sh} script, specific functionalities rely both

in @code{cli_getRepoName} and repository file system organization to

achieve their goals.  Consider @code{cli_getRepoName} function as

central place to manage file name convenctions for other functions

inside @file{centos-art.sh} script.

@quotation

@strong{Important} @code{cli_getRepoName} function doesn't verify file

or directory existence, for that purpose use @code{cli_checkFiles}

function instead.

@end quotation

The @var{NAME} variable contains the file name or directory name you

want to sanitate.

The @var{TYPE} variable specifies what type of sanitation you want to

perform on @var{NAME}. The @var{TYPE} can be one of the following

values:

@table @option

@item d

@itemx directory

Sanitate directory @var{NAME}s.

@item f

@item regular-file

Sanitate regular file @var{NAME}s.

@end table

Use @code{cli_getRepoName} function to sanitate file names and

directory names before their utilization. 

Use @code{cli_getRepoName} when you need to change file name

convenctions inside @file{centos-art.sh} script. 

When changing file name convenctions inside @code{cli_getRepoName}

what you are really changing is the way functions interpret repository

file system organization. In order to a complete file name convenction

change, you also need to change file names and directory names inside

repository file system organization, just as you did in

@code{cli_getRepoName} function. 

@quotation

@strong{Note} @xref{trunk Scripts Bash Functions Path}, for more

information on how to rename files and directories massively inside

repository file system organization.