Ubuntu Manpage: Config::Augeas - Edit configuration files through Augeas C library

Provided by: libconfig-augeas-perl_1.000-3build4_amd64

NAME

       Config::Augeas - Edit configuration files through Augeas C library

SYNOPSIS

         use Config::Augeas;

         my $aug = Config::Augeas->new( root => $aug_root ) ;

         my $ret = $aug->get("/files/etc/hosts/1/ipaddr") ;
         $aug->set("/files/etc/hosts/2/ipaddr","192.168.0.1") ;

         my @a = $aug->match("/files/etc/hosts/") ;

         my $nb = $aug->count_match("/files/etc/hosts/") ;

         $aug->save ;

DESCRIPTION

       Augeas is a library and command line tool that focuses on the most basic problem in handling Linux
       configurations programmatically: editing actual configuration files in a controlled manner.

       To that end, Augeas exposes a tree of all configuration settings (well, all the ones it knows about) and
       a simple local API for manipulating the tree. Augeas then modifies underlying configuration files
       according to the changes that have been made to the tree; it does as little modeling of configurations as
       possible, and focuses exclusively on transforming the tree-oriented syntax of its public API to the
       myriad syntaxes of individual configuration files.

       This module provides an object oriented Perl interface for Augeas configuration edition library with a
       more "perlish" API than Augeas C counterpart.

Constructor

new ( ... )

       Creates a new Config::Augeas object. Optional parameters are:

       loadpath
           a colon-spearated list of directories that lenses should be searched in. This is in addition to the
           standard load path and the directories in specified "AUGEAS_LENS_LIB" environment variable.

       root
           Use "root" as the filesystem root. If not specified, use the value of the environment variable
           "AUGEAS_ROOT". If that doesn't exist either, use ""/"".

       save => backup | newfile | noop
           Specify how to save the configuration file. Either create a newfile (with extension ".augnew", and do
           not overwrite the original file) or move the original file into a backup file (".augsave" extension).
           "noop" make saves a no-op process, just record what would have changed

       type_check => 1
           Typecheck lenses; since it can be very expensive it is not done by default.

       no_std_inc
           Do not use the builtin load path for modules

       no_load
           Do not load the tree from AUG_INIT

Methods

defvar( name, [ expr ])
Define a variable "name" whose value is the result of evaluating "expr". If a variable "name" already
exists, its name will be replaced with the result of evaluating "expr".

If "expr" is omitted, the variable "name" will be removed if it is defined.

Path variables can be used in path expressions later on by prefixing them with '$'.

Returns -1 on error; on success, returns 0 if "expr" evaluates to anything other than a nodeset, and the
number of nodes if "expr" evaluates to a nodeset

defnode ( name, expr, value )
Define a variable "name" whose value is the result of evaluating "expr", which must evaluate to a
nodeset. If a variable "name" already exists, its name will be replaced with the result of evaluating
"expr".

If "expr" evaluates to an empty nodeset, a node is created, equivalent to calling "set( expr, value)" and
"name" will be the nodeset containing that single node.

Returns undef on error

Returns an array containing:

• the number of nodes in the nodeset

• 1 if a node was created, and 0 if it already existed.

get( path )
Lookup the value associated with "path". Returns the value associated with "path" if "path" matches
exactly one node. If PATH matches no nodes or more than one node, returns undef.

set ( path, value )
Set the value associated with "path" to "value". "value" is copied into Augeas internal data structure.
Intermediate entries are created if they don't exist. Return 1 on success, 0 on error. It is an error if
more than one node matches "path".

text_store ( lens, node, path )
Use the value of node "node" as a string and transform it into a tree using the lens "lens" and store it
in the tree at "path", which will be overwritten. "path" and "node" are path expressions.

text_retrieve ( lens, node_in, path, node_out )
Transform the tree at "path" into a string using lens "lens" and store it in the node "node_out",
assuming the tree was initially generated using the value of node "node_in". "path", "node_in", and
"node_out" are path expressions.

insert ( label, before | after , path )
Create a new sibling "label" for "path" by inserting into the tree just before or just after "path".

"path" must match exactly one existing node in the tree, and "label" must be a label, i.e. not contain a
'/', '*' or end with a bracketed index '[N]'.

Return 1 on success, and 0 if the insertion fails.

remove ( path )
Remove path and all its children. Returns the number of entries removed. All nodes that match "path",
and their descendants, are removed. ("remove" can also be called with "rm")

move ( src, dest )
Move the node SRC to DST. SRC must match exactly one node in the tree. DST must either match exactly one
node in the tree, or may not exist yet. If DST exists already, it and all its descendants are deleted. If
DST does not exist yet, it and all its missing ancestors are created.

Note that the node SRC always becomes the node DST: when you move "/a/b" to "/x", the node "/a/b" is now
called "/x", no matter whether "/x" existed initially or not. ("move" can also be called with "mv")

Returns 1 in case of success, 0 otherwise.

rename ( src, dest )
Rename the label of all nodes matching "src" to "lbl".

Returns the number of nodes renamed on success and -1 on failure.

span ( path )
Returns a hash containing the "filename", "label_start", "label_end", "value_start", "value_end",
"span_start" and "span_end" of the given "path".

Example:

my $span = $aug->span('/files/etc/passwd/root') ;
# If filename is undefined, there are no valid span information for this node
if ($span->{filename}) {
print "Found root in passwd at character $span->{span_start}\n" ;
}

WARNING: You must check that $span->{filename} is defined. If it isn't, the node has no span information
and all other values in the hash are wrong.

match ( pattern )
Returns an array of the elements that match of the path expression "pattern". The returned paths are
sufficiently qualified to make sure that they match exactly one node in the current tree.

count_match ( pattern )
Same as match but return the number of matching element in manner more efficient than using "scalar
match( pattern )"

save
Write all pending changes to disk. Return 0 if an error is encountered, 1 on success. Only files that had
any changes made to them are written. "save" will follow backup files as specified with
Config::Augeas::new "backup" parameter.

load
Load files into the tree. Which files to load and what lenses to use on them is specified under
"/augeas/load" in the tree; each entry "/augeas/load/NAME" specifies a 'transform', by having itself
exactly one child 'lens' and any number of children labelled 'incl' and 'excl'. The value of NAME has no
meaning.

The 'lens' grandchild of "/augeas/load" specifies which lens to use, and can either be the fully
qualified name of a lens 'Module.lens' or '@Module'. The latter form means that the lens from the
transform marked for autoloading in "MODULE" should be used.

The 'incl' and 'excl' grandchildren of "/augeas/load" indicate which files to transform. Their value are
used as glob patterns. Any file that matches at least one 'incl' pattern and no 'excl' pattern is
transformed. The order of 'incl' and 'excl' entries is irrelevant.

When init is first called, it populates "/augeas/load" with the transforms marked for autoloading in all
the modules it finds.

Before loading any files, "load" will remove everything underneath "/augeas/files" and "/files",
regardless of whether any entries have been modified or not.

Returns 0 on error, 1 on success. Note that success includes the case where some files could not be
loaded. Details of such files can be found as '"/augeas//error"'.

print ( [ path , [ file ] ] )
Print each node matching "path" and its descendants on STDOUT or in a file

The second parameter can be :

• A file name.

• Omitted. In this case, print to STDOUT

If path is omitted, all Augeas nodes will be printed.

Example:

$aug->print ; # print all nodes to STDOUT
$aug->print('/files') ; # print all file nodes to STDOUT
$aug->print('/augeas/','bar.txt'); # print Augeas meta data in bar.txt

WARNING: The parameter order is reversed compared to Augeas C API.

srun ( [ text , [ file ] ] )
Run one or more newline-separated commands listed in "text". Running just "help" will print what
commands are available. Commands accepted by this are identical to what augtool accepts.

The second parameter can be :

• A file name.

• Omitted. In this case, print to STDOUT

The function returns the number of executed commands on success, and 0 otherwise.

Error reporting

   error
       Returns the error code from the last API call as a short string: noerror, nomem, internal, pathx,
       nomatch, manymatch, syntax, nolens, multiple_transforms

   error_message
       Return a human-readable message for the error code.

   error_minor_message
       Return a human-readable message elaborating the error code; might be undef. For example, when the error
       code is "pathx", this will explain how the path expression is invalid.

   error_details
       Return details about the error, which might be undef. For example, for "pathx", indicates where in the
       path expression the error occurred. The returned value can only be used until the next API call

CAVEATS

       Object oriented design would suggest to use a new class to represent Augeas errors, but this would stray
       too far from current Augeas design and API.

AUTHORS

       •   Dominique Dumont, <ddumont at cpan dot org@<gt>

       •   Raphael Pinson, <raphink at cpan dot org@<gt>

COPYRIGHT AND LICENSE

       •   Copyright (C) 2008-2010 by Dominique Dumont

       •   Copyright (C) 2011-2012 by Raphael Pinson

       This library is free software; you can redistribute it and/or modify it under the LGPL terms.