SAN FRANCISCO--Efforts to prevent the Linux from splitting into several incompatible versions--a problem that has in the past hobbled Unix, the operating system upon which Linux is modeled--moved several steps ahead this week.

On Wednesday, three versions of Linux--Red Hat 7.3, SuSE 8.0 Professional and Mandrake ProSuite 8.2--became the first products certified to comply with the guidelines of the Linux Standard Base (LSB).

The LSB, administered by the Free Standards Group, a nonprofit organization of software developers and information technology industry members, in effect standardizes many of the basic parts of Linux while allowing companies to add their own features atop that foundation.

The issue of Linux unity has even acquired some political overtones as Sun Microsystems Chief Executive Scott McNealy, a recent Linux convert, pledged LSB support at the LinuxWorld Conference and Expo while carping that Red Hat's top-end edition isn't compliant.

Avoiding fragmentation is a crucial challenge for the commercial success of Linux, which depends in part on the support of software companies such as Oracle, whose programs make Linux computers useful. If software companies have to support several incompatible versions of Linux, they'll shy away.

Linux is "not nearly as fragmented as Unix became in the 1980s, but there are significant differences which impact developers," said Nick Christenson, senior analyst at Minneapolis-based file storage software maker Sistina Software.

Versions of Unix from Sun Microsystems, IBM and Hewlett-Packard work somewhat differently, meaning that it can take months for a software company such as Veritas to translate and test its software to expand Unix support. The gulf between different versions of Unix is widened by the fact that they use different underlying microprocessors--unlike Linux, which most often runs on Intel chips such as the Pentium.

These variations among Unix versions have lent power to Microsoft's promises of a simpler world, where one operating system works on hardware from multiple computer makers.

But LSB certification, while helpful in preventing Linux from fragmenting into incompatible versions that can't run the same software, isn't all that's needed to make versions of Linux interchangeable. Some software needing particular high-performance features bypasses the domain of LSB, reaching directly into the heart, or kernel, of Linux, an area LSB won't standardize.

"Typically what happens if you don't have something like LSB is that you get such stupid, thoughtless variations between platforms that you just want to throw your hands up," said Illuminata analyst Jonathan Eunice. But such standards efforts lag real-world practices by years and don't govern everything. "They cover the basics, but an operating system is a really complicated piece of machinery."

The LSB has been under development for years but progress has recently been hastened.

The LSB isn't the only unification effort afoot. Several Linux sellers are using the exact same Linux software through the UnitedLinux alliance, while the Embedded Linux Consortium has created a first-draft proposal for standardizing Linux in computing devices such as network routers or factory robots.

But how useful?
BMC, a company that sells server management software for Linux and several other operating systems, is among those happy with the LSB. Currently, BMC must maintain separate versions of its server management software for Red Hat and SuSE, said Fred Johannessen, director of strategy and business development for BMC's Linux business unit.

"We're certified to Red Hat and SuSE, but in the long term, we will be moving to the LSB certification," he said. The company also expects to certify its own software with the LSB, he said.

LSB isn't as directly useful for others whose software reaches deep down into the kernel. For example, database companies such as Oracle require "asynchronous input-output" features in the heart of Linux that lets a computer make many simultaneous requests to read and write data on a storage system, said Markus Rex, vice president of development at SuSE.

"If you need direct links to the kernel, you need more than LSB," he said.

Sistina is in the same situation with its file-storage software, which lets large numbers of servers share the same storage system without stepping on each others' toes. The software reaches directly into the kernel, an area LSB doesn't govern.

Instead, Sistina relies on the unifying force that stems from the version of Linux posted at kernel.org by Linux founder Linus Torvalds and his deputies. Different Linux sellers tend to minimize variations from this version, Christenson said.

LSB discourages fragmentation in general, though, so Sistina supports it. "We're in favor even if it doesn't directly help us at this point," Christenson said. "The more similar the (Linux) distributions get, the easier our job becomes."

LSB is gradually expanding its domain as new technologies settle down, said LSB chairman George Kraft IV, an IBM software engineer. For example, future LSB versions will standardize the way Linux handles "threads"--computing processes that can be started with relative ease.

"We expect it to be put into the (LSB) specification as soon as it stabilizes," Kraft said, a move that will make it easier to run Java

Red Hat on board
An important ally in the LSB is dominant Red Hat, which according to market researcher IDC garnered nearly three-quarters of the money spent by businesses on the Linux operating system. Red Hat has built software alliances with major software companies including database seller Oracle, storage software maker Veritas and e-commerce software seller BEA Systems.

"The (Linux sellers) had to come together," said Mike Balma, HP's Linux business strategist. "A lot of people said it could never happen."

Red Hat believes in the merits of LSB certification, but doesn't believe companies such as Oracle will drop Red Hat certification in favor of LSB certification, said Paul Cormier, executive vice president of engineering.

Red Hat will LSB-certify its Advanced Server version, possibly with an update to the existing version 2.1 but certainly with 3.0, due in the second quarter of 2003, Cormier said. LSB compliance, which requires changes to software "libraries" that handle many standard software tasks, can't just be overlaid on an existing product.

Even with LSB compliance, software companies will still sign partnerships with Linux sellers to deal with issues such as the quality of support, the speed with which bugs are fixed or the ability to build in new features such as asynchronous input-output, Cormier said.

Not just the LSB
Another move against fragmentation took place with the formation in May of UnitedLinux, an agreement that Conectiva, Caldera International, Turbolinux and SuSE all will use SuSE's version of Linux for Intel servers.

The alliance was founded to reduce development expenses and to make life easier for software companies that often just certified their software with Linux from Red Hat. UnitedLinux on Wednesday announced its first beta, or test version, of the product, with public beta testing scheduled to begin by the end of September.

HP is among the backers of UnitedLinux as well as the LSB. It helps both in selling servers and in creating software such as HP's OpenView management software, Balma said.

UnitedLinux will comply with LSB, its backers say. Indeed, since it uses the exact same software base, many of the standardization issues are made easier to work out. However, Illuminata's Eunice said, customers using different higher-level software, such as management tools from different UnitedLinux partners, might not find it a trivial task to switch.

If Linux fans veer from the course, there's always the cautionary tale of Unix to pull them back into alignment. "I don't know that (LSB) is all that's necessary, but it's a step in the right direction," said Steve Solazzo, general manager of IBM's Linux efforts. "Everyone has a bad taste in their mouth from the fragmentation of Unix."