Spanish supermarket Mercadona is rolling out Red Hat Linux across 10,000 desktops.
A value for the contract win was not disclosed. The open source operating system will also be installed on all point of sale terminals and servers, using Red Hat Enterprise Linux.
The Spanish company, which refers to itself as the 'confident supermarket', reckons its processing speeds will increase fourfold after the migration.
A spokesman said in a statement that the implementation will "eventually lead to the optimisation of our customers' time in supermarkets, making the checkout process easier and helping cashier staff to process payments".
While Linux and other open source software, often for applications, has for some time been making headway in certain European municipalities, at the start of the month Red Hat won business with LVM, a large German insurance company, and BPU Banca, an Italian banking group.
These deals weren't about replacing Windows — one followed on from custom-built Linux clients and the other saw Solaris-based workstations ditched for Intel PCs running Red Hat's distribution — but they involved several thousand machines.
The latest in an increasingly long line of studies comparing the ongoing ownership costs of Windows- and Linux-based corporate computing environments came out at the start of the month. A Yankee Group analyst — to some criticism — said that there is very little difference between the two options.