General(3p)

NAME
Config::General - Generic Config Module

SYNOPSIS
 #
 # the OOP way
 use Config::General;
 $conf = Config::General->new("rcfile");
 my %config = $conf->getall;

 #
 # the procedural way
 use Config::General qw(ParseConfig SaveConfig SaveConfigString);
 my %config = ParseConfig("rcfile");

DESCRIPTION
This module opens a config file and parses its contents for you. The new method requires one parameter which needs to be a filename. The method getall returns a hash which contains all options and its associated values of your config file.

The format of config files supported by Config::General is inspired by the well known Apache config format, in fact, this module is 100% compatible to Apache configs, but you can also just use simple
 name/value pairs in your config files.

In addition to the capabilities of an Apache config file it supports some enhancements such as here-documents, C-style comments or multiline options.

SUBROUTINES/METHODS

new()
    Possible ways to call new():

     $conf = Config::General->new("rcfile");

     $conf = Config::General->new(\%somehash);

     $conf = Config::General->new( %options ); # see below for description of possible options

    This method returns a Config::General object (a hash blessed into "Config::General" namespace. All further methods must be used from that returned object. see below.

    You can use the new style with hash parameters or the old style which is of course still supported. Possible parameters to new() are:

    * a filename of a configfile, which will be opened and parsed by the parser

    or

    * a hash reference, which will be used as the config.

    An alternative way to call new() is supplying an option- hash with one or more of the following keys set:

    -ConfigFile
        A filename or a filehandle, i.e.:

         -ConfigFile => "rcfile" or -ConfigFile => \$FileHandle

    -ConfigHash
        A hash reference, which will be used as the config, i.e.:

         -ConfigHash => \%somehash

    -String
        A string which contains a whole config, or an arrayref containing the whole config line by line. The parser will parse the contents of the string instead of a file. i.e:

         -String => $complete_config

        it is also possible to feed an array reference to -String:

         -String => \@config_lines

    -AllowMultiOptions
        If the value is "no", then multiple identical options are disallowed. The default is "yes". i.e.:

         -AllowMultiOptions => "yes"

        see IDENTICAL OPTIONS for details.

    -LowerCaseNames
        If set to a true value, then all options found in the config will be converted to lowercase. This allows you to provide case-in-sensitive configs. The values of the options will not lowercased.

    -UseApacheInclude
        If set to a true value, the parser will consider "include ..." as valid include statement (just like the well known Apache include statement).

        It also supports apache's "IncludeOptional" statement with the same behavior, that is, if the include file doesn't exist no error will be thrown.

    -IncludeRelative
        If set to a true value, included files with a relative path (i.e. "cfg/blah.conf") will be opened from within the location of the configfile instead from within the location of the script($0). This works only if the configfile has a absolute pathname (i.e. "/etc/main.conf").

        If the variable -ConfigPath has been set and if the file to be included could not be found in the location relative to the current config file, the module will search within -ConfigPath for the file. See the description of -ConfigPath for more details.

    -IncludeDirectories
        If set to a true value, you may specify include a directory, in which case all files inside the directory will be loaded in ASCII order. Directory includes will not recurse into subdirectories. This is comparable to including a directory in Apache-style config files.

    -IncludeGlob
        If set to a true value, you may specify a glob pattern for an include to include all matching files (e.g. <<include conf.d/*.conf>>). Also note that as with standard file patterns, * will not match dot-files, so <<include dir/*>> is often more desirable than including a directory with -IncludeDirectories.

        An include option will not cause a parser error if the glob didn't return anything.

    -IncludeAgain
        If set to a true value, you will be able to include a sub-configfile multiple times. With the default, false, you will get a warning about duplicate includes and only the first include will succeed.

        Reincluding a configfile can be useful if it contains data that you want to be present in multiple places in the data tree. See the example under "INCLUDES".

        Note, however, that there is currently no check for include recursion.

    -ConfigPath
        As mentioned above, you can use this variable to specify a search path for relative config files which have to be included. Config::General will search within this path for the file if it cannot find the file at the location relative to the current config file.

        To provide multiple search paths you can specify an array reference for the path. For example:

         @path = qw(/usr/lib/perl /nfs/apps/lib /home/lib);
         ..
         -ConfigPath => \@path

    -MergeDuplicateBlocks
        If set to a true value, then duplicate blocks, that means blocks and named blocks, will be merged into a single one (see below for more details on this). The default behavior of Config::General is to create an array if some junk in a config appears more than once.

    -MergeDuplicateOptions
        If set to a true value, then duplicate options will be merged. That means, if the same option occurs more than once, the last one will be used in the resulting config hash.

        Setting this option implies -AllowMultiOptions == false unless you set -AllowMultiOptions explicit to 'true'. In this case duplicate blocks are allowed and put into an array but duplicate options will be merged.

    -AutoLaunder
        If set to a true value, then all values in your config file will be laundered to allow them to be used under a -T taint flag. This could be regarded as circumventing the purpose of the -T flag, however, if the bad guys can mess with your config file, you have problems that -T will not be able to stop. AutoLaunder will only handle a config file being read from -ConfigFile.

    -AutoTrue
        If set to a true value, then options in your config file, whose values are set to true or false values, will be normalised to 1 or 0 respectively.

        The following values will be considered as true:

         yes, on, 1, true

        The following values will be considered as false:

         no, off, 0, false

        This effect is case-insensitive, i.e. both "Yes" or "No" will result in 1.

    -FlagBits
        This option takes one required parameter, which must be a hash reference.

        The supplied hash reference needs to define variables for which you want to preset values. Each variable you have defined in this hash-ref and which occurs in your config file, will cause this variable being set to the preset values to which the value in the config file refers to.

        Multiple flags can be used, separated by the pipe character |.

        Well, an example will clarify things:

         my $conf = Config::General->new(
                 -ConfigFile => "rcfile",
                 -FlagBits => {
                      Mode => {
                         CLEAR    => 1,
                         STRONG   => 1,
                         UNSECURE => "32bit" }
                 }
         );

        In this example we are defining a variable named "Mode" which may contain one or more of "CLEAR", "STRONG" and "UNSECURE" as value.

        The appropriate config entry may look like this:

         # rcfile
         Mode = CLEAR | UNSECURE

        The parser will create a hash which will be the value of the key "Mode". This hash will contain all flags which you have pre-defined, but only those which were set in the config will contain the pre-defined value, the other ones will be undefined.

        The resulting config structure would look like this after parsing:

         %config = (
                     Mode => {
                               CLEAR    => 1,
                               UNSECURE => "32bit",
                               STRONG   => undef,
                             }
                   );

        This method allows the user (or, the "maintainer" of the configfile for your application) to set multiple pre-defined values for one option.

        Please beware, that all occurrences of those variables will be handled this way, there is no way to distinguish between variables in different scopes. That means, if "Mode" would also occur inside a named block, it would also parsed this way.

        Values which are not defined in the hash-ref supplied to the parameter -FlagBits and used in the corresponding variable in the config will be ignored.

        Example:

         # rcfile
         Mode = BLAH | CLEAR

        would result in this hash structure:

          %config = (
                     Mode => {
                               CLEAR    => 1,
                               UNSECURE => undef,
                               STRONG   => undef,
                             }
                   );

        "BLAH" will be ignored silently.

    -DefaultConfig
        This can be a hash reference or a simple scalar (string) of a config. This causes the module to preset the resulting config hash with the given values, which allows you to set default values for particular config options directly.

        Note that you probably want to use this with -MergeDuplicateOptions, otherwise a default value already in the configuration file will produce an array of two values.

    -Tie
        -Tie takes the name of a Tie class as argument that each new hash should be based off of.

        This hash will be used as the 'backing hash' instead of a standard Perl hash, which allows you to affect the way, variable storing will be done. You could, for example supply a tied hash, say Tie::DxHash, which preserves ordering of the keys in the config (which a standard Perl hash won't do). Or, you could supply a hash tied to a DBM file to save the parsed variables to disk.

        There are many more things to do in tie-land, see tie to get some interesting ideas.

        If you want to use the -Tie feature together with -DefaultConfig make sure that the hash supplied to -DefaultConfig must be tied to the same Tie class.

        Make sure that the hash which receives the generated hash structure (e.g. which you are using in the assignment: %hash = $config->getall()) must be tied to the same Tie class.

        Example:

         use Config::General qw(ParseConfig);
         use Tie::IxHash;
         tie my %hash, "Tie::IxHash";
         %hash = ParseConfig(
                   -ConfigFile => shift(),
                   -Tie => "Tie::IxHash"
                 );

    -InterPolateVars
        If set to a true value, variable interpolation will be done on your config input. See Config::General::Interpolated for more information.

    -InterPolateEnv
        If set to a true value, environment variables can be used in configs.

        This implies -InterPolateVars.

    -AllowSingleQuoteInterpolation
        By default variables inside single quotes will not be interpolated. If you turn on this option, they will be interpolated as well.

    -ExtendedAccess
        If set to a true value, you can use object oriented (extended) methods to access the parsed config. See Config::General::Extended for more information.

    -StrictObjects
        By default this is turned on, which causes Config::General to croak with an error if you try to access a non-existent key using the OOP-way (-ExtendedAcess enabled). If you turn -StrictObjects off (by setting to 0 or "no") it will just return an empty object/hash/scalar. This is valid for OOP-access 8via AUTOLOAD and for the methods obj(), hash() and value().

    -StrictVars
        By default this is turned on, which causes Config::General to croak with an error if an undefined variable with InterPolateVars turned on occurs in a config. Set to false (i.e. 0) to avoid such error messages.

    -SplitPolicy
        You can influence the way how Config::General decides which part of a line in a config file is the key and which one is the value. By default it tries its best to guess. That means you can mix equalsign assignments and whitespace assignments.

        However, sometime you may wish to make it more strictly for some reason. In this case you can set -SplitPolicy. The possible values are: 'guess' which is the default, 'whitespace' which causes the module to split by whitespace, 'equalsign' which causes it to split strictly by equal sign, or 'custom'. In the latter case you must also set -SplitDelimiter to some regular expression of your choice. For example:

         -SplitDelimiter => '\s*:\s*'

        will cause the module to split by colon while whitespace which surrounds the delimiter will be removed.

        Please note that the delimiter used when saving a config (save_file() or save_string()) will be chosen according to the current -SplitPolicy. If -SplitPolicy is set to 'guess' or 'whitespace', 3 spaces will be used to delimit saved options. If 'custom' is set, then you need to set -StoreDelimiter.

    -SplitDelimiter
        Set this to any arbitrary regular expression which will be used for option/value splitting. -SplitPolicy must be set to 'custom' to make this work.

    -StoreDelimiter
        You can use this parameter to specify a custom delimiter to use when saving configs to a file or string. You only need to set it if you want to store the config back to disk and if you have -SplitPolicy set to 'custom'.

        However, this parameter takes precedence over whatever is set for -SplitPolicy.

        Be very careful with this parameter.

    -CComments
        Config::General is able to notice c-style comments (see section COMMENTS). But for some reason you might no need this. In this case you can turn this feature off by setting -CComments to a false value('no', 0, 'off').

        By default -CComments is turned on.

    -BackslashEscape
        Deprecated Option.

    -SlashIsDirectory
        If you turn on this parameter, a single slash as the last character of a named block will be considered as a directory name.

        By default this flag is turned off, which makes the module somewhat incompatible to Apache configs, since such a setup will be normally considered as an explicit empty block, just as XML defines it.

        For example, if you have the following config:

         <Directory />
           Index index.awk
         </Directory>

        you will get such an error message from the parser:

         EndBlock "</Directory>" has no StartBlock statement (level: 1, chunk 10)!

        This is caused by the fact that the config chunk below will be internally converted to:

         <Directory></Directory>
           Index index.awk
         </Directory>

        Now there is one '</Directory>' too much. The proper solution is to use quotation to circumvent this error:

         <Directory "/">
           Index index.awk
         </Directory>

        However, a raw apache config comes without such quotes. In this case you may consider to turn on -SlashIsDirectory.

        Please note that this is a new option (incorporated in version 2.30), it may lead to various unexpected side effects or other failures. You've been warned.

    -UseApacheIfDefine
        Enables support for Apache <IfDefine> ... </IfDefine>. See -Define.

    -Define
        Defines the symbols to be used for conditional configuration files. Allowed arguments: scalar, scalar ref, array ref or hash ref.

        Examples:

         -Define => 'TEST'
         -Define => \$testOrProduction
         -Define => [qw(TEST VERBOSE)]
         -Define => {TEST => 1, VERBOSE => 1}

        Sample configuration:

          <Logging>
            <IfDefine TEST>
               Level Debug
               include test/*.cfg
            </IfDef>
            <IfDefine !TEST>
              Level Notice
               include production/*.cfg
            </IfDefine>
          </Logging>

    -ApacheCompatible
        Over the past years a lot of options has been incorporated into Config::General to be able to parse real Apache configs.

        The new -ApacheCompatible option now makes it possible to tweak all options in a way that Apache configs can be parsed.

        This is called "apache compatibility mode" - if you will ever have problems with parsing Apache configs without this option being set, you'll get no help by me. Thanks :)

        The following options will be set:

         UseApacheInclude   = 1
         IncludeRelative    = 1
         IncludeDirectories = 1
         IncludeGlob        = 1
         SlashIsDirectory   = 1
         SplitPolicy        = 'whitespace'
         CComments          = 0
         UseApacheIfDefine  = 1

        Take a look into the particular documentation sections what those options are doing.

        Beside setting some options it also turns off support for explicit empty blocks.

    -UTF8
        If turned on, all files will be opened in utf8 mode. This may not work properly with older versions of Perl.

    -SaveSorted
        If you want to save configs in a sorted manner, turn this parameter on. It is not enabled by default.

    -NoEscape
        If you want to use the data ( scalar or final leaf ) without escaping special character, turn this parameter on. It is not enabled by default.

    -NormalizeBlock
        Takes a subroutine reference as parameter and gets the current block or blockname passed as parameter and is expected to return it in some altered way as a scalar string. The sub will be called before anything else will be done by the module itself (e.g. interpolation).

        Example:

         -NormalizeBlock => sub { my $x = shift; $x =~ s/\s*$//; $x; }

        This removes trailing whitespaces of block names.

    -NormalizeOption
        Same as -NormalizeBlock but applied on options only.

    -NormalizeValue
        Same as -NormalizeBlock but applied on values only.

    -AlwaysQuoteOutput
        If set to true, then values containing whitespace will always quoted when calling save_string() or save_file().

getall()
    Returns a hash structure which represents the whole config.

files()
    Returns a list of all files read in.

save_file()
    Writes the config hash back to the hard disk. This method takes one or two parameters. The first parameter must be the filename where the config should be written to. The second parameter is optional, it must be a reference to a hash structure, if you set it. If you do not supply this second parameter then the internal config hash, which has already been parsed, will be used.

    Please note that any occurrence of comments will be ignored by getall() and thus be lost after you call this method.

    You need also to know that named blocks will be converted to nested blocks (which is the same from the perl point of view). An example:

     <user hans>
       id 13
     </user>

    will become the following after saving:

     <user>
       <hans>
          id 13
       </hans>
     </user>

    Example:

     $conf_obj->save_file("newrcfile", \%config);

    or, if the config has already been parsed, or if it didn't change:

     $conf_obj->save_file("newrcfile");

save_string()
    This method is equivalent to the previous save_file(), but it does not store the generated config to a file. Instead it returns it as a string, which you can save yourself afterwards.

    It takes one optional parameter, which must be a reference to a hash structure. If you omit this parameter, the internal config hash, which has already been parsed, will be used.

    Example:

     my $content = $conf_obj->save_string(\%config);

    or:

     my $content = $conf_obj->save_string();

CONFIG FILE FORMAT
Lines beginning with # and empty lines will be ignored. (see section COMMENTS!) Spaces at the beginning and the end of a line will also be ignored as well as tabulators. If you need spaces at the end or the beginning of a value you can surround it with double quotes. An option line starts with its name followed by a value. An equal sign is optional. Some possible examples:

 user    max
 user  = max
 user            max

If there are more than one statements with the same name, it will create an array instead of a scalar. See the example below.

The method getall returns a hash of all values.

BLOCKS
You can define a block of options. A block looks much like a block in the wellknown Apache config format. It starts with <blockname> and ends with </blockname>.

A block start and end cannot be on the same line.

An example:

 <database>
  host   = muli
  user   = moare
  dbname = modb
  dbpass = D4r_9Iu
 </database>

Blocks can also be nested. Here is a more complicated example:

 user   = hans
 server = mc200
 db     = maxis
 passwd = D3rf$
 <jonas>
  user    = tom
  db      = unknown
  host    = mila
  <tablestructure>
   index   int(100000)
   name    char(100)
   prename char(100)
   city    char(100)
   status  int(10)
   allowed moses
   allowed ingram
   allowed joice
  </tablestructure>
 </jonas>

The hash which the method getall returns look like that:

  print Data::Dumper(\%hash);
  $VAR1 = {
           'passwd' => 'D3rf$',
           'jonas'  => {
                        'tablestructure' => {
                                             'prename' => 'char(100)',
                                             'index'   => 'int(100000)',
                                             'city'    => 'char(100)',
                                             'name'    => 'char(100)',
                                             'status'  => 'int(10)',
                                             'allowed' => [
                                                           'moses',
                                                           'ingram',
                                                           'joice',
                                                          ]
                                            },
                        'host'           => 'mila',
                        'db'             => 'unknown',
                        'user'           => 'tom'
                       },
           'db'     => 'maxis',
           'server' => 'mc200',
           'user'   => 'hans'
          };

If you have turned on -LowerCaseNames (see new()) then blocks as in the following example:

 <Dir>
  <AttriBUTES>
   Owner  root
  </attributes>
 </dir>

would produce the following hash structure:

  $VAR1 = {
           'dir' => {
                     'attributes' => {
                                      'owner'  => "root",
                                     }
                    }
          };

As you can see, the keys inside the config hash are normalized.

Please note, that the above config block would result in a valid hash structure, even if -LowerCaseNames is not set! This is because Config::General does not use the block names to check if a block ends, instead it uses an internal state counter, which indicates a block end.

If the module cannot find an end-block statement, then this block will be ignored.

NAMED BLOCKS
If you need multiple blocks of the same name, then you have to name every block. This works much like Apache config. If the module finds a named block, it will create a hashref with the left part of the named block as the key containing one or more hashrefs with the right part of the block as key containing everything inside the block(which may again be nested!). As examples says more than words:

# given the following sample
 <Directory /usr/frisco>
  Limit Deny
  Options ExecCgi Index
 </Directory>
 <Directory /usr/frik>
  Limit DenyAll
  Options None
 </Directory>

# you will get:

  $VAR1 = {
           'Directory' => {
                           '/usr/frik' => {
                                           'Options' => 'None',
                                           'Limit' => 'DenyAll'
                                          },
                           '/usr/frisco' => {
                                             'Options' => 'ExecCgi Index',
                                             'Limit' => 'Deny'
                                            }
                          }
          };

You cannot have more than one named block with the same name because it will be stored in a hashref and therefore be overwritten if a block occurs once more.

WHITESPACE IN BLOCKS
The normal behavior of Config::General is to look for whitespace in block names to decide if it's a named block or just a simple block.

Sometimes you may need blocknames which have whitespace in their names.

With named blocks this is no problem, as the module only looks for the first whitespace:

 <person hugo gera>
 </person>

would be parsed to:

  $VAR1 = {
           'person' => {
                        'hugo gera' => {
                                       },
                       }
          };

The problem occurs, if you want to have a simple block containing whitespace:

 <hugo gera>
 </hugo gera>

This would be parsed as a named block, which is not what you wanted. In this very case you may use quotation marks to indicate that it is not a named block:

 <"hugo gera">
 </"hugo gera">

The save() method of the module inserts automatically quotation marks in such cases.

EXPLICIT EMPTY BLOCKS
Beside the notation of blocks mentioned above it is possible to use explicit empty blocks.

Normally you would write this in your config to define an empty block:

 <driver Apache>
 </driver>

To save writing you can also write:

 <driver Apache/>

which is the very same as above. This works for normal blocks and for named blocks.

IDENTICAL OPTIONS (ARRAYS)
You may have more than one line of the same option with different values. Example:

 log  log1
 log  log2
 log  log2

You will get a scalar if the option occurred only once or an array if it occurred more than once. If you expect multiple identical options, then you may need to check if an option occurred more than once:

  $allowed = $hash{jonas}->{tablestructure}->{allowed};
  if (ref($allowed) eq "ARRAY") {
    @ALLOWED = @{$allowed};
    else {
      @ALLOWED = ($allowed);
    }
  }

The same applies to blocks and named blocks too (they are described in more detail below). For example, if you have the following config:

 <dir blah>
  user max
 </dir>
 <dir blah>
  user hannes
 </dir>

then you would end up with a data structure like this:

  $VAR1 = {
           'dir' => {
                     'blah' => [
                                {
                                 'user' => 'max'
                                },
                                {
                                 'user' => 'hannes'
                                }
                               ]
                    }
          };

As you can see, the two identical blocks are stored in a hash which contains an array(-reference) of hashes.

Under some rare conditions you might not want this behavior with blocks (and named blocks too). If you want to get one single hash with the contents of both identical blocks, then you need to turn the new() parameter -MergeDuplicateBlocks on (see above). The parsed structure of the example above would then look like this:

  $VAR1 = {
           'dir' => {
                     'blah' => {
                                'user' => [
                                           'max',
                                           'hannes'
                                          ]
                               }
                    }
          };

As you can see, there is only one hash "dir->{blah}" containing multiple "user" entries. As you can also see, turning on -MergeDuplicateBlocks does not affect scalar options (i.e. "option = value"). In fact you can tune merging of duplicate blocks and options independent from each other.

If you don't want to allow more than one identical options, you may turn it off by setting the flag AllowMultiOptions in the new() method to "no". If turned off, Config::General will complain about multiple occurring options with identical names!

  FORCE SINGLE VALUE ARRAYS
You may also force a single config line to get parsed into an array by turning on the option -ForceArray and by surrounding the value of the config entry by []. Example:

 hostlist = [ foo.bar ]

Will be a singlevalue array entry if the option is turned on. If you want it to remain to be an array you have to turn on -ForceArray during save too.

LONG LINES
If you have a config value, which is too long and would take more than one line, you can break it into multiple lines by using the backslash character at the end of the line. The Config::General module will concatenate those lines to one single-value.

Example:

 command = cat /var/log/secure/tripwire | \
 mail C<-s> "report from tripwire" \
 honey@myotherhost.nl

command will become: "cat /var/log/secure/tripwire | mail "-s" 'report from twire' honey@myotherhost.nl"

HERE DOCUMENTS
You can also define a config value as a so called "here-document". You must tell the module an identifier which indicates the end of a here document. An identifier must follow a "<<".

Example:

 message <<EOF
  we want to
  remove the
  homedir of
  root.
 EOF

Everything between the two "EOF" strings will be in the option message.

There is a special feature which allows you to use indentation with here documents. You can have any amount of whitespace or tabulators in front of the end identifier. If the module finds spaces or tabs then it will remove exactly those amount of spaces from every line inside the here-document.

Example:

 message <<EOF
    we want to
    remove the
    homedir of
    root.
    EOF

After parsing, message will become:

 we want to
 remove the
 homedir of
 root.

because there were the string " " in front of EOF, which were cut from every line inside the here-document.

INCLUDES
You can include an external file at any position in your config file using the following statement in your config file:

 <<include externalconfig.rc>>

If you turned on -UseApacheInclude (see new()), then you can also use the following statement to include an external file:

 include externalconfig.rc

This file will be inserted at the position where it was found as if the contents of this file were directly at this position.

You can also recursively include files, so an included file may include another one and so on. Beware that you do not recursively load the same file, you will end with an error message like "too many open files in system!".

By default included files with a relative pathname will be opened from within the current working directory. Under some circumstances it maybe possible to open included files from the directory, where the configfile resides. You need to turn on the option -IncludeRelative (see new()) if you want that. An example:

 my $conf = Config::General(
  -ConfigFile => "/etc/crypt.d/server.cfg"
  -IncludeRelative => 1
 );

/etc/crypt.d/server.cfg:

 <<include acl.cfg>>

In this example Config::General will try to include acl.cfg from /etc/crypt.d:

 /etc/crypt.d/acl.cfg

The default behavior (if -IncludeRelative is not set!) will be to open just acl.cfg, wherever it is, i.e. if you did a chdir("/usr/local/etc"), then Config::General will include:

 /usr/local/etc/acl.cfg

Include statements can be case insensitive (added in version 1.25).

Include statements will be ignored within C-Comments and here-documents.

By default, a config file will only be included the first time it is referenced. If you wish to include a file in multiple places, set /-IncludeAgain to true. But be warned: this may lead to infinite loops, so make sure, you're not including the same file from within itself!

Example:

 # main.cfg
 <object billy>
  class=Some::Class
 <printers>
  include printers.cfg
 </printers>
 # ...
 </object>
  <object bob>
   class=Another::Class
  <printers>
  include printers.cfg
  </printers>
  # ...
 </object>

Now "printers.cfg" will be include in both the "billy" and "bob" objects.

You will have to be careful to not recursively include a file. Behaviour in this case is undefined.

COMMENTS
A comment starts with the number sign #, there can be any number of spaces and/or tab stops in front of the #.

A comment can also occur after a config statement. Example:

 username = max  # this is the comment

If you want to comment out a large block you can use C-style comments. A /* signals the begin of a comment block and the */ signals the end of the comment block. Example:

 user  = max # valid option
 db    = tothemax
 /*
 user  = andors
 db    = toand
 */

In this example the second options of user and db will be ignored. Please beware of the fact, if the Module finds a /* string which is the start of a comment block, but no matching end block, it will ignore the whole rest of the config file!

NOTE: If you require the # character (number sign) to remain in the option value, then you can use a backslash in front of it, to escape it. Example:

 bgcolor = \#ffffcc

In this example the value of $config{bgcolor} will be "#ffffcc", Config::General will not treat the number sign as the begin of a comment because of the leading backslash.

Inside here-documents escaping of number signs is NOT required!

PARSER PLUGINS
You can alter the behavior of the parser by supplying closures which will be called on certain hooks during config file processing and parsing.

The general aproach works like this:

  sub ck {
    my($file, $base) = @_;
    print "_open() tries $file ... ";
    if ($file =~ /blah/) {
      print "ignored\n";
      return (0);
    } else {
      print "allowed\n";
      return (1, @_);
    }
  }

  my %c = ParseConfig(
                      -IncludeGlob      => 1,
                      -UseApacheInclude => 1,
                      -ConfigFile       => shift,
                      -Plug             => { pre_open => *ck }
                     );

Output:

 _open() tries cfg ... allowed
 _open() tries x/*.conf ... allowed
 _open() tries x/1.conf ... allowed
 _open() tries x/2.conf ... allowed
 _open() tries x/blah.conf ... ignored

As you can see, we wrote a little sub which takes a filename and a base directory as parameters. We tell Config::General via the Plug parameter of new() to call this sub everytime before it attempts to open a file.

General processing continues as usual if the first value of the returned array is true. The second value of that array depends on the kind of hook being called.

The following hooks are available so far:

pre_open
    Takes two parameters: filename and basedirectory.

    Has to return an array consisting of 3 values:

     - 1 or 0 (continue processing or not)
     - filename
     - base directory

pre_read
    Takes two parameters: the filehandle of the file to be read and an array containing the raw contents of said file.

    This hook will be applied in _read(). File contents are already available at this stage, comments will be removed, here-docs normalized and the like. This hook gets the unaltered, original contents.

    Has to return an array of 3 values:

     - 1 or 0 (continue processing or not)
     - the filehandle
     - an array of strings

    You can use this hook to apply your own normalizations or whatever.

    Be careful when returning the abort value (1st value of returned array 0), since in this case nothing else would be done on the contents. If it still contains comments or something, they will be parsed as legal config options.

post_read
    Takes one parameter: a reference to an array containing the prepared config lines (after being processed by _read()).

    This hook will be applied in _read() when everything else has been done.

    Has to return an array of 2 values:

     - 1 or 0 (continue processing or not) [Ignored for post hooks]
     - a reference to an array containing the config lines

pre_parse_value
    Takes 2 parameters: an option name and its value.

    This hook will be applied in _parse_value() before any processing.

    Has to return an array of 3 values:

     - 1 or 0 (continue processing or not)
     - option name
     - value of the option

post_parse_value
    Almost identical to pre_parse_value, but will be applied after _parse_value() is finished and all usual processing and normalization is done.

Not implemented yet: hooks for variable interpolation and block parsing.

OBJECT ORIENTED INTERFACE
There is a way to access a parsed config the OO-way. Use the module Config::General::Extended, which is supplied with the Config::General distribution.

VARIABLE INTERPOLATION
You can use variables inside your config files if you like. To do that you have to use the module Config::General::Interpolated, which is supplied with the Config::General distribution.

EXPORTED FUNCTIONS
Config::General exports some functions too, which makes it somewhat easier to use it, if you like this.

How to import the functions:

 use Config::General qw(ParseConfig SaveConfig SaveConfigString);

ParseConfig()
    This function takes exactly all those parameters, which are allowed to the new() method of the standard interface.

    Example:

     use Config::General qw(ParseConfig);
     my %config = ParseConfig(-ConfigFile => "rcfile", -AutoTrue => 1);

SaveConfig()
    This function requires two arguments, a filename and a reference to a hash structure.

    Example:

     use Config::General qw(SaveConfig);
     ..
     SaveConfig("rcfile", \%some_hash);

SaveConfigString()
    This function requires a reference to a config hash as parameter. It generates a configuration based on this hash as the object-interface method save_string() does.

    Example:

     use Config::General qw(ParseConfig SaveConfigString);
     my %config = ParseConfig(-ConfigFile => "rcfile");
     .. # change %config something
     my $content = SaveConfigString(\%config);

CONFIGURATION AND ENVIRONMENT
No environment variables will be used.

SEE ALSO
I recommend you to read the following documents, which are supplied with Perl:

 perlreftut                     Perl references short introduction
 perlref                        Perl references, the rest of the story
 perldsc                        Perl data structures intro
 perllol                        Perl data structures: arrays of arrays

 Config::General::Extended      Object oriented interface to parsed configs
 Config::General::Interpolated  Allows one to use variables inside config files

LICENSE AND COPYRIGHT
Copyright (c) 2000-2025 Thomas Linden

This library is free software; you can redistribute it and/or modify it under the same terms of the Artistic License 2.0.

BUGS AND LIMITATIONS
See rt.cpan.org for current bugs, if any.

INCOMPATIBILITIES
None known.

DIAGNOSTICS
To debug Config::General use the Perl debugger, see perldebug.

DEPENDENCIES
Config::General depends on the modules FileHandle, File::Spec::Functions, File::Glob, which all are shipped with Perl.

AUTHOR
Thomas Linden <tlinden |AT| cpan.org>

VERSION
2.67