Currently, yakpro-po only works on 1.x branch of PhpParser.  
A new 2.0 PHP Parser has been released with a different API,  
and drop support for PHP < 5.4  
Unfortunately, This new branch is the default one.  

Please use :  
git clone --branch=1.x https://github.com/nikic/PHP-Parser.git  

1. Prerequisites: git and php-cli (command line interface) packages. 
   on ubuntu: (adapt according your linux distribution) 
   # apt-get install git 
   # apt-get install php5-cli 
2. Navigate to the directory where you want to install yakpro-po (/usr/local is a good idea) : 
   # cd /usr/local 
3. Then retrieve from GitHub: 
   # git clone https://github.com/pk-fr/yakpro-po.git 
4. Go to the yakpro-po directory: 
   # cd yakpro-po 
5. Then retrieve from GitHub: 
   # git clone --branch=1.x https://github.com/nikic/PHP-Parser.git 
6. Check that yakpro-po.php has execute rights, otherwise:
                                        # chmod a+x yakpro-po.php 
7. Create a symbolic link in the /usr/local/bin directory
   # cd /usr/local/bin 
   # ln -s /usr/local/yakpro-po/yakpro-po.php yakpro-po 
8. You can now run yakpro-po 
   # yakpro-po --help 
   # yakpro-po test.php 

Modify a copy of the yakpro-po.cnf to fit your needs...
Read the "Configuration file loading algorithm" section of this document
to choose the best location suiting your needs!

That's it! You're done!

--config-file argument value
YAKPRO_PO_CONFIG_FILE environment variable value if existing and not empty.

filename selection:
       YAKPRO_PO_CONFIG_FILENAME environment variable value if existing and not empty,
       yakpro-po.cnf otherwise.

 file is then searched in the following directories:
        YAKPRO_PO_CONFIG_DIRECTORY  environment variable value if existing and not empty.
        current_working_directory
        current_working_directory/config
        home_directory
        home_directory/config
        /usr/local/YAK/yakpro-po
        source_code_directory/default_conf_filename

  if no config file is found, default values are used.

  You can find the default config file as an example in the yakpro-po.cnf file of the
  repository.
  Do not modify it directly because it will be overwritten at each update!
  Use your own yakpro-po.cnf file (for example in the root directory of your project)

  When working on directories,
  context is saved in order to reuse the same obfuscation translation table.
  When you make some changes in one or several source files,
  yakpro-po uses timestamps to only reobfuscate files that were changed
  since the last obfuscation.
  This can save you a lot of time.

  caveats: does not delete files that are no more present...
           use --clean  command line parameter, and then re-obfuscate all!

--silent                            do not display Information level messages.
--debug                             (internal debugging use) displays the syntax tree.

-s or
--no-strip-indentation              multi line output
--strip-indentation                 single line output

--no-shuffle-statements             do not shuffle statements
--shuffle-statements                       shuffle statements

--no-obfuscate-string-literal       do not obfuscate string literals
--obfuscate-string-literal                 obfuscate string literals

--no-obfuscate-loop-statement       do not obfuscate loop statements
--obfuscate-loop-statement                 obfuscate loop statements

--no-obfuscate-if-statement         do not obfuscate if statements
--obfuscate-if-statement                   obfuscate if statements

--no-obfuscate-constant-name        do not obfuscate constant names
--obfuscate-constant-name                  obfuscate constant names

--no-obfuscate-variable-name        do not obfuscate variable names
--obfuscate-variable-name                  obfuscate variable names

--no-obfuscate-function-name        do not obfuscate function names
--obfuscate-function-name                  obfuscate function names

--no-obfuscate-class_constant-name  do not obfuscate class constant names
--obfuscate-class_constant-name            obfuscate class constant names

--no-obfuscate-class-name           do not obfuscate class names
--obfuscate-class-name                     obfuscate class names

--no-obfuscate-interface-name       do not obfuscate interface names
--obfuscate-interface-name                 obfuscate interface names

--no-obfuscate-trait-name           do not obfuscate trait names
--obfuscate-trait-name                     obfuscate trait names

--no-obfuscate-property-name        do not obfuscate property names
--obfuscate-property-name                  obfuscate property names

--no-obfuscate-method-name          do not obfuscate method names
--obfuscate-method-name                    obfuscate method names

--no-obfuscate-namespace-name       do not obfuscate namespace names
--obfuscate-namespace-name                 obfuscate namespace names

--no-obfuscate-label-name           do not obfuscate label names
--obfuscate-label-name                     obfuscate label names

--scramble-mode     identifier|hexa|numeric         force scramble mode
--scramble-length   length ( min=2; max = 16 for scramble_mode=identifier,
                                    max = 32 for scramble_mode = hexa or numeric)

-h or
--help                              displays help.

If your obfuscated software makes use of external libraries
that you do not obfuscate along with your software:

if the library consists of functions:
        set the $conf->obfuscate_function_name to false in your yakpro-po.cnf config file,
        or declare all the functions names you are using in $conf->t_ignore_functions
        example : $conf->t_ignore_functions = array('my_func1','my_func2');

if the library consists of classes :
        set the $conf->obfuscate_class_name,
                $conf->obfuscate_property_name,
                $conf->obfuscate_method_name
        to false in your yakpro-po.cnf config file...
        ... or declare all the classes, properties, methods names you are using in
                $conf->t_ignore_classes,
                $conf->t_ignore_properties,
                $conf->t_ignore_methods.

This is also true for PDO::FETCH_OBJ that retrieves properties from external source
(i.e. database columns).

At first you can test obfuscating only variable names...


If you obfuscate functions, do not use indirect function calls like
    $my_var = 'my_function';
    $my_var();
or put all the function names you call indirectly in the $conf->t_ignore_functions array!


Do not use indirect variable names!
    $$my_var = something;
or put all the variable names you use indirectly in the $conf->t_ignore_variables array!


Do not use PDO::FETCH_OBJ  but use PDO::FETCH_ASSOC instead!
or disable properties obfuscation in the config file.


If you use the define function for defining constants, the only allowed form is when the
define function has exactly 2 arguments, and the first one is a litteral string!
You MUST disable constants obfuscation in the config file, if you use any other forms
of the define function!
There is no problem with the const MY_CONST = something; form!

Except for the statements shuffling obfuscation option,
the obfuscated program speed is almost the same than the original one.

$conf->shuffle_stmts    is set to true by default.

If you encounter performance issues, you can either set the option to false,
or fine tune the shuffle parameters with the associated options.

You must know that the lesser the chunk size, the better the obfuscation,
and the lower your software performance!

(during my own tests, the maximum of obfuscation costs me about 13% of performance)

You can tune it as you wish!