| .cshrc | .plan | .twmrc | 16-bit application | 32-bit application |
| 386BSD | 386SPART.PAR | A/UX | AEGIS | AIDX |
| AUTOEXEC.BAT | Accounting File | Active Directory | Advanced Interactive eXecutive | Allegro |
| Amoeba | Andrew File System | Angel | ArchBSD | Architecture Neutral Distribution Format |
| Artemis microkernel | BOS | BS2000 | BSD/OS | Bad command or file name |
| Basic Input/Output System | Basic Operating System | Basic Programming Support | BeOS | Berkeley Software Distribution |
| Blue Box | Blue Screen of Life | Broadway | C shell | CAE |
| CLI | CMAY | CONFIG.SYS | CTOS | Chorus |
| Command Control Processor | Common Applications Environment | Common Desktop Environment | Communications Server | Compatible Timesharing System |
| Control Program | Control Program for Microcomputers | Convergent Technologies Operating System | DNIX | DOS |
| DOS/360 | DTSS | Darwin | Dataless Management Services | Debian |
| Debian GNU/Hurd | Desktop Management Interface | Device Manager | Disk Operating System | Distributed Network Operating System |
| ERGO-Shell | EXEC 8 | Edinburgh Multi Access System | Enhanced Directory Service | EntireX |
| Execute Channel Program | Extended System Configuration Data | Extensible Shell | FCB | FDISK |
| FTX | Fedora | Finder | Fredette's Operating System Interface Language | FreeBSD |
| GCOS | GEM | GEORGE 3 | GNU Network Object Model Environment | GNUStep |
