Terminal keeps stating "command not found" when trying to create a bootable installer with High Sierra

in addition to MrHoffmans good advice, Your USB stick should be erased and named exactly MyVolume, so that no changes to the command as written in the article are required.

The download must be present in the /Applications folder, because that command you execute is located inside

Install macOS High Sierra.app

you placed there .

You must be VERY careful to select the ENTIRE command out of the article, preferably by triple-clicking on it. The way it is displayed encourages you to select the visible portion, and ignore the rest of the command that either wraps around in is invisible at the end of the displayed line.

The command is either not being entered as listed, or the macOS High Sierra installer has not been downloaded.

For the former, the command can be cut-and-pasted from the Related Article, linked above.

For the latter, follow the link to the App Store in the Related Article, and download or re-download the installer.

If you are unsure, post the command and the resulting error messages here, using the </> code tags.

If that were a required step, the Apple article on making USB-Stick installers would call it out as an explicit required step along the way.

Those articles were written and extensively reviewed by precise mathematical thinkers. DON'T add any extra steps.

vlevel358 wrote:

Okay, I did that because I read somewhere that it said that is how you find out if it works. Thank you!!

I would encourage dutifully following the Apple directions and not going off-script, particularly when starting out.

I would doubly encourage dutifully following the instructions whenever going off-script fails.

Or as this approach is known locally, “when all else fails, read the instructions”. 😜

You DON'T open it to see if it works.

If you copied it faithfully and it has the right name:

Install macOS High Sierra.app

... it works.