Terminal error: command not found

You first have to run the .pkg app after mounting the .dmg file. Running the .pkg file will extract the real installer into the Applications folder. Then & only then will you be able to use the command line to make the bootable USB installer. Also, this .pkg file will only work when run on a computer which is compatible with macOS 10.11 (the computer can be running any version of macOS 10.6+). Generally a compatible Mac for 10.11 is one from 2008 to 2015, but you can use the information in this article to confirm:

https://eshop.macsales.com/guides/Mac_OS_X_Compatibility

Edit: Forgot to include the official Apple instructions for downloading macOS installers......make sure to read the instructions associated with the older 10.7 to 10.12 installers.

How to download and install macOS - Apple Support

kashi226 wrote:

Want to make bootable flash drive but getting error command not found

Then you're not doing it right.

Read Create a bootable installer for macOS - Apple Support. Those instructions must be followed precisely.

Can you copy & paste the exact command you used here?