NAME

Config::Writer - a module to write configuration files in an easy and safe way.

DESCRIPTION

This module is intended to perform the next operations:

• safe temporary configuration file creation, ownership and access mode setting;

• creation of backup file(-s) of the target configuration file;

• automatic cleanup of outdated or surplus backup files.

Now you are able to restore configuration file even if you forgot to create a backup file before editing it!

CAVEATS

• This module is written using `signatures` feature. As for me, it makes code clearer. However, it requires perl 5.10+. All more or less modern OSes has much more newer perl included, so don't think it will be a problem.

SYNOPSIS

my $fh = Config::Writer->new('file.conf', {
    'workdir'     => '/usr/local/etc',
    'owner'       => 'nobody',
    'permissions' => 0640,
    'retain'      => 4
});
die "can not open file for writing" if $fh->error;
$fh->sayf('# Configuration file created with %s', $0);
$fh->close;

METHODS

new(FILENAME, { OPTIONS })

Create new Config::Writer object as follows:

my $fh = Config::Writer->new('file.conf', {
    'workdir'       => '/path/to/workdir',
    'retain'        => 3,
    'overwrite'     => 1,
    'extension'     => '-%+4Y-%m-%d',
    'owner'         => 'bird',
    'group'         => 'bird',
    'permissions'   => 0640
});

Configuration file to be created or replaced name can contain either absolute or relative path part. Path part handling is described in workdir option description below.

New temporary file will be created on success and all write operations will be performed on this temporary file. On `close` method invocation existing configuration file can be moved to a backup file (see descrition of overwrite option below) and temporary file is renamed in place of the original configuration file.

FILENAME

Configuration file to be created or replaced name. Can contain either absolute or relative path part. Path part handling is described in workdir option description below.

New temporary file will be created on success and all write operations will be performed on this temporary file. On close() method invocation existing configuration file can be moved to a backup file (see descrition of overwrite option below) and temporary file is renamed in place of the original configuration file.

format = STRING

Configuration file format. Currently unused.

workdir = STRING

If filename contains absolute path, work directory is set to a dirname(1) implicitly regardless of whether workdir option is set or not.

If workdir is not set, work directory defaults to getcwd(3).

If filename contains relative path, it is appended to a work directory name, provided either in workdir option or returned by getcwd(3).

Work directory existence check is performed. If work directory does not exist, `undef` is returned and error flag is set!

retain = INTEGER

Quantity of configuration file backups to retain. Default is 0 - do not retain any.

overwrite = BOOLEAN

Existing backup file will be either overwritten if the flag is set to true (overwrite = 1) or stayed untouched (overwrite = 0). E. g. if you choose to store single backup per day, you'll get either the latest configuration version before it being updated, or the configuration you've got at the beginning of the day.

Default is 0.

extension = STRING

Configuration file backup extension format as described in POSIX strftime function documentation. The new extension will replace original one, so the backup files should not be loaded even in case wildcards (e. g. '*.conf') are used to include configuration from a several files. Existing backup files will either stay untouched or overwritten depending on overwrite flag value.

Default is '-%Y-%m-%d'.

owner = STRING

Configuration file owner name. If file owner can not be changed, error flag is set.

Defaults to process EUID.

group = STRING

Configuration file group name. If not provided, process EGID is used.

permissions = OCTAL

Configuration file permissions in numeric format. Read chmod(1) manual for details.

Default is 0600.

error()

Takes no arguments. Returns `false` if Config::Writer object is defined and `error` flag is not set and `true` otherwise.

say(STRING)

Is equivalent to print() method except that $/ is added to the end of the line.

sayf(STRING, ARRAY)

Is equivalent to printf() method except that $/ is added to the end of the format line.

print(STRING)

Prints STRING to temporary file as is.

printf(STRING, ARRAY)

Prints formatted string to the temporary file. See printf(3) for more details.

close()

When called:

• closes temporary configuration file;

• tries to rename target configuration file to a backup file (if `retain` option is non-zero);

• tries to remove surplus (oldest) backup files (if `retain` option is non-zero);

• tries to rename temporary configuration file to a target name.

If any errors occurs, `error` flag is set.

AUTHORS

• Volodymyr Pidgornyi, vp<at>dtel-ix.net;

CHANGELOG

v0.0.4

- Minor CPAN compatibility fixes;

- README.md is generated from Netbox/Config.pm now.

v0.0.3

PAUSE compatibility issues fixed.

v0.0.2

sayf() metrod added.

v0.0.1

Initial release, since basic features seems to work as intended.

TODO

• Implement helpers for a different configuration files formats.