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Your typical Mac will start with something called Open Firmware, which loads the OS and things like that. Now, it is basically like a DOS shell: it can be used to type commands and boot into various OSes and run recovery programs. Now, this shell is accessible by any end-user who owns a Mac by pressing Command-Option-O-F when the Apple logo appears. You will see some text, and you will be dropped into a DOS-like shell. Here is a short list of commands you may use:
mac-boot -> boots into OS X
dev -> configures devices
ls -> Lists hardware configuration
dir -> does exactly as it does in DOS, lists files in a specified directory
devalias -> shows you the different aliases and what they're for
load -> loads a kernel into RAM
boot -> boots a loaded kernel
printenv -> shows the environment variables
setenv -> allows you to make and change system variables, namely Open Firmware ones
shut-down -> shuts down your Mac
reboot -> reboots your Mac into OS X, although you could sue mac-boot for that!
Thanks for reading this thread and if you know any more commands post them below please! :)
NOTE! I would not really recommend *messing* with Open Firmware as it can be very dangerous.

Edited by Member #758415 because: Changing erroneous info
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Dani AI

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Short clarification (for and ): Open Firmware is not a “DOS-like” user shell — it’s the machine’s pre‑boot firmware, implemented as a small Forth environment (IEEE 1275/Open Firmware) that runs before any Unix shell or macOS is available. Calling it a DOS shell is misleading: it’s a low‑level boot and device interface, not the bash/CLI you get after the OS boots. (openfirmware.org)

Which Macs actually have it: Open Firmware was shipped on PowerPC (New World) Macs. After Apple’s Intel transition the platform used EFI/UEFI instead, and modern Apple Silicon machines use a different secure‑boot/startup model — so the OF prompt and its commands only exist on older PPC hardware, not on most Macs sold since 2006. If you’re unsure what you have, check the CPU/“About This Mac” info and follow the platform‑specific recovery options. (ftp.swin.edu.au)

Safety and practical alternatives: changing firmware variables can leave a machine unbootable. On Intel Macs use Apple’s supported tools (macOS Recovery, Startup Manager, single‑user mode) and Apple’s documented NVRAM/PRAM reset procedure rather than guessing at low‑level firmware edits; Apple silicon handles NVRAM differently. Follow Apple’s official recovery/reset docs when troubleshooting modern machines. (support.apple.com)

If you are working with vintage PowerPC hardware: Open Firmware is powerful for device inspection and rescue (and it exposes persistent variables). There are safe, documented recovery sequences (for example: reset firmware/NVRAM to defaults) but they should be followed only from trustworthy guides — and backups or external boot media are recommended before you change anything. When in doubt, avoid altering variables and seek a vintage‑Mac guide or service. (mac-classic.com)

Summary: ’s distinction between firmware prompt and Unix shells is the right one; ’s curiosity is useful, but firmware-level changes carry real risk — use the platform-appropriate recovery tools and Apple’s documentation first.

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Member Avatar for macmad

DOS is not a shell. DOS is an OS. Shells are CLIs (command line interpreters) to parse code in unix. Please, if you wish to talk about other OSs, leave the others behind. The logic of DOS and the Logic of Unix are completely different.

Member Avatar for Member #758415

I said it was a DOS-like shell, not a DOS shell. Trust me, I have developed a bit too much on DOS.

Member Avatar for macmad

I don't want to put words into your mouth, but: "Now, it is basically like a DOS shell". Your words, not mine.

The unix shell that your system comes up with is a bash shell and all unix commands can be executed from the prompt. You can even switch to any unix shell.

Member Avatar for Member #758415

Fine. Editing the post.

Member Avatar for Member #758415

Fine. Editing the post.

Or not, as it seems. Stupid edit limit. Double-posting annoying? Sorry.

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