dbtool/dbtool.pod

# -*-cperl-*-
=head1 NAME

dbtool - a tool for storing key/value pairs in a hash database

=head1 SYNOPSIS

 dbtool -d database [DirusSfwVhtRFpP] [-k key] [-v value]

=head1 DESCRIPTION

This manual page documents the program B<dbtool>. B<dbtool> can be used
to store and retrieve data in a key/value format in
a hash database. Perl compatible regular expressions are supported
both for storing and retrieving of data. It's main advantages are the
ability to maintain huge amounts of data and speed.

=head1 OPTIONS

=over

=item B<-D>

Dump all key/value pairs of the database. Keys and values will be
separated by whitespace or by the character specified by B<-F>.

=item B<-f>

Enable B<force mode>, which has the following causes:

=over

=item I<insert>

Keys (and the associated value) will be overwritten if it already
exists.

=item I<update>

Key/value will be created if it does not exist.

=back

=item B<-F> -I<separator>

Optional field separator. The default separator is one whitespace.
Use B<-F> in conjunction with B<-D> to specify an alternate output
field separator or with B<-i> if data is read in from I<STDIN> (without
B<-k> and B<-v>).

=item B<-h>

Prints out a short help message to I<STDERR> and exits.

=item B<-i>

Insert data. The B<-k> and B<-v> options are required. You will get an error
message if the key already exists. Use B<-f> to avoid such a message
and let B<dbtool> overwrite the key instead.
 If both key (B<-k>) and value (B<-v>) are not provided, B<dbtool>
will read in the data from I<STDIN>. The default input separator
is one whitespace. The first field (separated by whitespace) will be
considered as the key and the rest of the input line will be considered
as the value associated with the key. You can provide an alternate
input field separator using the option B<-F>.
 It is also possible to separate the key and value of an input line
using a regular expression with the B<-t> option(see below).

=item B<-k> I<key>

Use I<key> as the key. Use B<-k> in conjunction with B<-i>, B<-u>, B<-r>,
B<-s> or B<-S>.

=item B<-r>

Remove data. Only the key to be removed (B<-k>) is required.

=item B<-R>

Reverse the meaning of the expression provided with B<-t>. By default
B<dbtool> will use the first match as the key and the second one as
the value. With B<-R> this will be reversed.

=item B<-s>

Search for a key specified by B<-k>. The associated value will be printed
to I<STDOUT>. You can use B<-w> to get the key too separated by whitespace
or by the parameter of B<-F>. You can only search for keys, not for values.

=item B<-S>

Search for a key. The parameter to the option B<-k> will be considered
as a perl compatible regular expression. It is possible to get multiple
results, which will be printed to I<STDOUT> separated by newline. Otherwise
B<-S> behaves like B<-s>.

=item B<-t> I<expression>

Use I<expression> to decide which part of an input line has to be used as the
key and which one as the value. The regular expression must contain two
parts surrounded by round parenthesis'. See the section EXAMPLES for some
uses of B<-t>. This option can only be used in conjunction with B<-i> without
B<-k> and B<-v>.

=item B<-u>

Update data. A key (B<-k>) and a value (B<-v>) is required. You will get an
error message if the key does not exist. You can use the option B<-f> to avoid
such a message and to insert the data if it does not exist instead.

=item B<-p>

Use encrypted database. dbtool will ask you for the passphrase,
unless the environment variable DB_PASSPHRASE is set.


=item B<-P> I<passphrase>

Use encrypted database. Specify the passphrase on the commandline.

=item B<-v> I<value>

Use I<value> as the value associated with some key. Use B<-v> in conjunction
with B<-i>, B<-u> or B<-r>.

=item B<-V>

Print out the version of B<dbtool>.

=item B<-w>

Print search results together with the associated keys separated by whitespace
or the parameter of B<-F>.

=back



=head1 EXPRESSIONS

Regular expressions are provided using the B<PCRE Library>. It supports most of
the features which perl provides. See the section <20>DIFFERENCES FROM PERL<52> in the PCRE
manpage. You can also take a look to the perl regular expression man page with
the following command:

 perldoc perlre

(which requires perl to be installed).


=head1 ENCRYPTION

As of version 1.4 B<dbtool> supports encrypted databases. See the descriptions
of the options B<-p> and B<-P>. The algorithm used for encryption is B<Rijndael>
block cipher encryption.

B<dbtool> does not use the passphrase which the user supplies. It uses instead
the MD5 digest of the passphrase as the encryption key.

Please note, that B<dbtool> itself does not distinguish between encrypted or
unencrypted databases. That means, you will get strange results if you try
to access an encrypted database without the options B<-p> or B<-P> being set.

B<dbtool> by default will only encrypt the values of a database, not the keys.
This might change in future versions.



=head1 EXAMPLES

=over

=item

 dbtool -d test.db -i -k "test" -v "blah blah blah"

Insert the key  "test" which is associated to the value
"blah blah blah" into test.db.


=item

 dbtool -d test.db -u -f -k "test" -v "blubber"

Update the key "test" even if it does not exist with "blubber".


=item

 dbtool -d test.db -r -k "test"

Remove the entry to which the key "test" points.


=item

 dbtool -d test.db -S -k "^\d\d"

Search for all keys which start at least with two digits.


=item

 dbtool -d test.db -D | grep -i "tom"

Dump out the whole database test.db and search for "tom". This 
method allows you to search for values.


=item

 cat /etc/passwd | dbtool -d test.db -i -f -t "^(.+?):.*:(\d+?):$"

In this example we store the contents of the file passwd in
a hash database. The username will be the key of an entry and
the userid will be the associated value. The key must be any character
from the beginning of a line until the first appearance of a colon.
The value must be one or more digits after the 2nd colon until the next
colon:

 apache:x:48:48:Apache:/var/www:/bin/false
 ^^^^^^   ^^
 |        |
 |        o--- value
 |
 o------------ key


=item

 find /home -ls | dbtool -d catalog.dbm -i -f -R -t "^(.+?) (\/.*)$"

In this example the output of the unix command 'find /home -ls' will
be used as input for B<dbtool>. The key for an entry will begin on the
first appearance of a slash character until the end of the line. Everything
in front of it will be the value (because of the B<-R>):

 302  12 -rw------- 1 scip  scip    9734 Feb 11  2000 /home/scip/D/lrk5/README
 (---------------[ value ]--------------------------) (--------[ key ]-------)

I use this command in my backup script for creating a catalog of all saved files
and it's attributes.

 
=back


=head1 REPORTING BUGS

Report bugs on L<https://github.com/tlinden/dbtool/issues> or mail to <tlinden@cpan.org>.


=head1 COPYRIGHT

Copyright (c) 2000-2015 T.v. Dein.
This is free software; see the source for copying conditions.  There is NO warranty;
not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


=head1 SEE ALSO

=over

=item B<perldoc perlre>

Perl regular expressions.

=item B<http://www.pcre.org>

The homepage of the B<PCRE> library.

=back


=head1 AVAILABILITY

B<dbtool> can be downloaded from B<http://www.daemon.de/DBTOOL>.


=head1 AUTHORS

I<T.v. Dein <tlinden@cpan.org>>



=cut