Point of sale
Depending on your needs, you have different options.
Odoo
Odoo, formerly known as OpenERP, is a suite of open-source business apps written in Python and released under the GPLv3 license. This suite of applications covers all business needs, from Website/Ecommerce down to manufacturing, inventory and accounting, all seamlessly integrated. Odoo's technical features include a distributed server, flexible workflows, an object database, a dynamic GUI, customizable reports, and an XML-RPC interface. Odoo is the most installed business software in the world. It is used by 2.000.000 users worldwide ranging from very small companies (1 user) to very large ones (300 000 users).
Alternatives not included in Trisquel
BananaPos
BananaPos is point of sale system that consists of a server, a client, libraries, and some associated utilities. The client is GUI based on GTK. System administration is Web-based using PHP. The program currently supports only MySQL.
Simple Invoices
Simple Invoices is a clean, simple, and basic Web-based invoicing system. It is meant for personal invoices, home office invoicing, small organization invoicing, and basic POS (point of sale) systems for light usage. Its goals are to be easy to use, simple and clean, and focused on its task. It is not meant for heavy-use POS applications, nor is it meant to be enterprise ready.
AllCommerce
AllCommerce is an e-commerce/content application based on Perl and SQL92 databases which runs under Unix/GNU+Linux/Win2000 using SQL database engines (MySQL/Postgres/etc). It provides a shopping cart as well as tools for content, merchandise, statistics, vendor, order, and inventory. Its modular design allows it to be used as a complete or partial solution.
PILA
PILA is a software system to run a bookstore. It is made up of various modules, including front-end point-of-sale, stock, catalog and financial sales reports. The Web page is currently in Portuguese only. It is intended to be used with MIOLO (https://web.archive.org/web/20130114031918/http://www.solis.org.br/projetos/miolo), a set of PHP-based object oriented database connectors. It is currently in use at several bookstores in Brazil that use completely free software systems.
closedShop
closedShop' attempts to provide an easy to set up, manage and utilize shopping cart. Based on Perl and MySQL, its aim will be to provide all the features a commercial shopping cart offers at no cost. Users can search for items by description, title, or category, and they can have individual accounts for checking order status. The package has a cookie based shopping cart, so customers can continue shopping. It also has email confirmations for both customer and administrator, as well as the ability to manage a mailing list of customers. It has a relatively secure user/admin authentication without a secure server -- with a secure server (for which there is support), you would be very secure.
Interchange
Interchange is a complete web-based application server It can create, automate and database-enable your web-site, and build on-line applications. It can be used as part of a standalone system or as part of a larger system. The Interchange demo application is ecommerce-based, so ecommerce has inevitably become its main use. The ecommerce demo and admin system supports sales, order processing, content management, customer service, and has been implemented for traditional retail sales, digital goods delivery, B2B parts re-ordering, non-commerce content management, auctions, order status checking, and supply chain management (among others). It can be integrated with payment processing services, ERP systems, point-of-sale systems, accounting systems, external content management systems, and Java-based application servers (among others). Interchange is made up of the following components: database abstraction layer, a generic templating system, transaction routing rules, a customer information object, a universal localization scheme, a security blackout definition, profiles, filters, a search language, and session management.
Openbravo
"Familiar desktop application-like UI makes Openbravo easy to learn for new users and accelerates adoption rates at your company"
"Conduct order taking and execution of other time-critical tasks with an editable spreadsheet-style grid that's familiar and fast to learn for users"
http://www.openbravo.com/content/openbravo-legal-java-pos
LemonPOS
"an open source Point of Sale software targeted for micro, small and medium businesses. MySQL is employed for data management and storage, and can be used a single database with many POS terminals on a network. [...]Lemon provides a modern themeable and easy to use Interface, a search panel, a price-checker tool, an administration tool for managing your store, printed reports, and more..."
http://lemonpos.org/ (also in Trisquel repositories)
Source
community members, http://trisquel.info/en/forum/anyone-knows-about-good-pos-seller-gnulinux
