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Author image T. Linden


Config::General - Generic Config Module


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

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


This module opens a config file and parses it's 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 it's 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.



Possible ways to call new():

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

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

 $conf = new Config::General( %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


* 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:


A filename or a filehandle, i.e.:

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

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

 -ConfigHash => \%somehash

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

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

 -AllowMultiOptions => "no"

see IDENTICAL OPTIONS for details.


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.


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


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.


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.

You must specify the path as an array ref. For example:

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

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.


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 dupclicate options will be merged.


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.


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 "oN" will result in 1.


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 = new Config::General(
         -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

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 occurencies 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.


 # rcfile
 Mode = BLAH | CLEAR

would result in this hash structure:

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

"BLAH" will be ignored silently.


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.


-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.


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

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


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


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().


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.


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 it's best to guess. That means you can mix equalsign assignments and whitespace assignments.

However, somtimes 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 whitespaces which surrounds the delimiter will be removed.

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


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.


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'.

Be very carefull with this parameter.


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.


If you turn on this parameter, a backslash can be used to escape any special character within configurations.

By default it is turned off.


Returns a hash structure which represents the whole config.


Writes the config hash back to the harddisk. 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 occurence 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

will become the following after saving:

      id 13


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

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


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.


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


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


Lines begining with # and empty lines will be ignored. (see section COMMENTS!) Spaces at the begining 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 use apostrophs ". An optionline starts with it's name followed by a value. An equalsign 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.


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>. An example:

    host   = muli
    user   = moare
    dbname = modb
    dbpass = D4r_9Iu

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

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

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' => [
                       '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:

     Owner  root

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 blocknames 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.


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 /usr/frik>
        Limit DenyAll
        Options None

 # 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.


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>

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.


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 occured only once or an array if it occured more than once. If you expect multiple identical options, then you may need to check if an option occured 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 blah>
   user hannes

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',
                                  'user' => '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 occuring options with identical names!


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.


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

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


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


 message <<EOF
   we want to
   remove the
   homedir of

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 whitespaces 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.


 message <<EOF
         we want to
         remove the
         homedir of

After parsing, message will become:

   we want to
   remove the
   homedir of

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


You can include an external file at any posision 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 recurively 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 errormessage 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

  <<include acl.cfg>>

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


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


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

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


A comment starts with the number sign #, there can be any number of spaces and/or tabstops 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 backlsash 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!


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.


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


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


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


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

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


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

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.


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


I recommend you to read the following documentations, 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 to use variables inside config files


Copyright (c) 2000-2004 Thomas Linden

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


none known yet.


Thomas Linden <tom@daemon.de>