#::#!<%PERL%>

#  dbishell: A generic database shell based on the Perl DBI layer
#  Copyright (C) 2000  Vivek Dasmohapatra (vivek@etla.org)

#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.

#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.

#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

#::use lib '<%LDIR%>';

use strict;

use DBIShell;
use DBIShell::Term_CTL;
use DBIShell::UTIL qw(:context);

use constant VERSION       => '0.8.09';

use constant LICENSE_BLURB => <<LicenseBlurb;

 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\\/<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 >> dbishell version ${\VERSION}, Copyright (C) 2000 Vivek Dasmohapatra <<
 >> dbishell comes with ABSOLUTELY NO WARRANTY; for details        <<
 >> type `license'.  This is free software, and you are welcome    <<
 >> to redistribute it under certain conditions; type `license'    <<
 >> for details.                                                   <<
 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>/\\<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

LicenseBlurb

my $SHELL;
$SHELL = DBIShell->new();            # let there be shell...

#$SHELL->install_sigwinch_handler();
#&{$SIG{WINCH}}();

$SHELL->getopts();                   # kick off the main body
$SHELL->connect()                    # connect to the specified data source
  || ($SHELL->errputf(CONTEXT_NIL, "%s\n", $SHELL->error),exit());
warn(LICENSE_BLURB);                 # blah, blah, blah...
$SHELL->parse_loop();                # that's it: we're initalised: enter
                                     # the despatch loop. dispatch? sp?
warn(LICENSE_BLURB);                 # blah, blah, blah...
warn("Thank you for using dbishell... feedback welcome (vivek\@etla.org)\n");

my $x = getppid();

fork() ? exit(0) : kill('WINCH',$x);

__END__

# TLF: Nikola Tesla died for you....

=pod

=head1 NAME

dbishell - a generic database shell based on the perl DBI layer

=head1 SYNOPSIS

  dbishell [ --driver drivername   ]
           [ --dsn dsn_name        ]
           [ --user username       ]
           [ --pass password       ]
           [ --shell-driver Driver ]
           [ --dotdir directory    ]

=head1 DESCRIPTION

dbishell is a generic database shell based on the perl DBI layer.
It provides all the functionality of a database specific shell such
as F<sqlplus> or F<mysql>, but in a database independant manner. In some
cases, it will be significantly more advanced than the command line
database shell supplied by your database vendor.

=head1 OPTIONS

=head2 --driver

This is the perl DBD driver you want to use. If you do not supply this,
dbishell will ask you for one. Some examples are:

=over 4

=item mysql

=item Oracle

=item Sybase

=item ODBC

=item Pg

=back

=head2 --dsn

This is the DSN you want to use. The DSN is the 'thing' which contains the
information required by the database client libraries in order to locate
and attempt to connect to the database server. The syntax of these DSNs
is database specific and sometimes confusing - for example, the 'hostname'
in Sybase DSN syntax does not specify the host to which you wish to
connect. It specifies the name which Sybase will use as the client's name
when it needs it.

If the perl DBI DSN for a database is 'dbi:mysql:FOO' then the dbishell
dsn is just 'FOO'.

If a dsn is not supplied, dbishell will ask for one.

=head2 --user

The username you wish to supply to the database while connecting

If a username is not supplied, dbishell will ask for one.

=head2 --pass

The password you wish to supply while connecting. This is provided for
convenience, but I do not recommend using it. If no password is supplied,
one will be asked for.

=head2 --shell-driver

If the name of the required dbishell driver cannot be inferred from the
--driver option [eg if you are using the DBD::ODBC driver, or are
using the Sybase driver to connect to an MS SQL database] then you may
specify the name of the dbishell driver here. Not used often.

=head2 --dotdir

The path to the directory where dbishell should look for its dotfiles.

=head1 USAGE

=head2 Line termination:

dbishell considers SQL commands to be ready for interpretation when
a '/' character is encountered at the end of a line. This character
was chosen for compatability with Oracle reasons, but can be
configured.

=head2 Tab completion:

Context sensetive tab completion is available, dbishell examines the
preceding word to establish a context, so in cases where this provides
insufficient information, dbishell falls back to 'dumb' completion.

=head2 Variables:

dbishell allows you to set and use variables and environment
variables in your commands [no scripting yet, though].

=head3 Setting Variables:

To set a variable, use the following syntax:

  prompt> $FOO=some value here

Quotes will not be treated specially, '\n' and '\t' will be expanded
to newlines and tabs, and variables on the RHS will be interpolated
before setting the LHS.

=head3 String Interpolation:

Variables of the form $NAME are interpolated directly into your
SQL command before being sent to the database for interpretation,
thus the database will be unaware that a variable was even used.

=head3 Bound Parameters:

Variables in your SQL statement in the forms:

   $>NAME
   $<NAME

Will be interpreted as input and input/output parameters respectively.
All parameters wil be bound as type VARCHAR. Note that your database
[or at least your DBD driver] must support bound parameters for this to
work, and not all parts of a query can have parameters bound into them.

=head2 Special Variables:

There are 2 special categories of variables:

=head3 Environment Variables:

These take the form $env:NAME, and allow access to the environment.
They carry no special restrictions that I am aware of, over and above
any imposed by the environment itself.

=head3 DBI Connection Parameters:

These take the form $dbi:NAME, and correspond to the DBI connection
parameters, such as AutoCommit and LongReadLen. You probably shouldn't
use them for anything else, such as bound parameters.

=head3 Other Important Variables:

=over 4

=item $FIELD_SEPARATOR

Contains the character sequence used to separate fields in output.
If unset, you get '|' as the separator.

=item $PRESCAN_FORMAT

If true, [cf. Perl "What is truth"] then the whole of the dataset
returned by all queries is prescanned, and the output formatted
accordingly This can be helpful when you have large columns which
typically hold values much shorter than they have the capacity for,
since it shrinks the display columns down to the size of the largest
output value on a per column basis. On the other hand, if you're
fetching large numbers of rows, This may hurt, since you'll be
prefetching the whole dataset into memory, scanning it, and then
printing it.

=item $TRUNCATE_COLUMN_NAMES

If false, a column will never be narrower than its name in the output.
Othewise, column names will be shortened to fit their columns display
widths [if PRESCAN_ROWS is set]

=item $CASE_SENSITIVE

Is the DB case sensitive or not? [mainly effects tab completion]

=item $PAGER

The command to open a pipe to, to use as a pager. If $PAGER is unset,
$env:PAGER is tried instead, and if there's nothing there, 'less -S'
is used instead. If that doesn't work, then bad things probably
happen. Like paging not working, and maybe your output disappearing.

=item $PAGING

If this is true, then output from certain commands [just selects at 
the moment] will be paged, depending on the value of $PAGE_SIZE and 
$PRESCAN_FORMAT

=item $PAGE_SIZE

The number of rows above which dbishell will try to page output.
Paging is decided as follows:

If $PAGING is true, and $PRESCAN_FORMAT is true, output exceeding
$PAGE_SIZE [or exceeding the size of the terminal, if $PAGE_SIZE
is 0 or unset] will be paged.

If $PRESCAN_FORMAT is false, and $PAGING is true, then output will 
be paged regardless of the amount of data returned, unless the DBI 
driver can determine the number of rows before they are all fetched.

=item $EOL

The end of line character used by dbishell to determine when you want
a command executed. If unset [the default] then '/' is used.  [except
that the '/' that terminates a comment will be ignored].  Otherwise,
whatever you put in $EOL will be scanned for.

=back

=head2 Commands:

dbishell implements a number of commands, which although not part of the SQL
standard, are very useful to have:

=head3 help

help TOPIC

Display the help for a particular command or keyword, or the dfault help
if nothing appropriate is found.

=head3 describe

describe THING

Display a description of the database object [usually a table] specified.
Some drivers can also describe indices, views, procedures etc...

=head3 read

read FILEPATH

Read in the file specified, as if the user was typing its contents in at the
prompt.

=head3 interpolation

interpolation on|off

Turn on or off variable interpolation.

=head3 escaping

escaping on|off

Turn on or off backslash escape interpretation.

=head3 show

show tables|views|THING|etc...

Give some information about the keyword in question
[eg list the tables, dump a create statement, show the SQL source for a
 procedure, that sort of thing]

=head3 subshell

!SUBSHELL COMMAND

If the first non whitespace is a '!', then your command is passed to a
subshell for interpretation. You can even launch dbishell from within itself
this way.

=head3 cd

Change the working directory.

=head3 spool

spool input|output|error|stderr|stdin|stdout FILEPATH on|off

Turn on or off logging of the relevant data stream to the file
specified by FILEPATH.

=head3 license

license

Display the license.

=head3 quit

quit

=head1 EXAMPLES

Some examples of starting DBIShell are given here:

dbishell --driver Oracle --dsn host=foobar\;sid=argh        --user=scott
dbishell --driver mysql  --dsn host=narf\;database=argh     --user vivek
dbishell --driver Sybase --dsn hostname=narf\;database=argh --user=sa
dbishell --driver ODBC   --dsn FOO:  --shell-driver=Sybase  --user sa

=head1 SEE ALSO

The F<README> file in the DBIShell distribution.

=head1 AUTHOR

Vivek Dasmohapatra (vivek@etla.org)

=cut