Unix Applications Are Portable

Because all the variants of Unix share almost all their major design features, programs written for one brand or variation of Unix are usually easily portable to other types of Unix. All Unix programs are a lot more portable between Unix brands than programs are between, say, Windows 98 and Windows NT.

This means that programs written for some other brand of Unix can almost always be ported to Linux rather easily. Linux didn't even exist when Sendmail (which carries over 80% of Internet e-mail), BIND (which handles almost all DNS services) and the other critical Internet applications were written, but they were easily ported to Linux.

Even commercial software is available for Linux. Oracle, Sybase, and other commercial software vendors have already ported or are in the process of porting their products to Linux. The large amount of common ground among the various strains of Unix simplifies this task enourmously.