In application Port, each character means something. It can be a small part of a code, a command line argument or part of a script. The "space" is not exempt from this feature of the Terminal either. A "space" typed in the Terminal in a command line argument, it will not be recognized as a space. Hence the error: Unexpected argument.
The simplest example is to use the tutorial in which we learn about how to change the default location (Desktop) to automatically save screen shots on macOS.
If we want the folder in which to save the screen shots to be "Screen Shots", then in the command line in the Terminal we will have to correctly define the argument for "space". Otherwise, after executing the command line we will meet her error.
Wonderland:
defaults write com.apple.screencapture location ~/Desktop/Screen Shots
To define a space between two words in the command line argument, we will use the character "\"Immediately after the first word.
Correct command line:
defaults write com.apple.screencapture location ~/Desktop/Screen\ Shots
Attention, the command line contains spaces. This tutorial only applies to command line arguments that contain spaces. In our case, a folder of which name is composed of two written words unbound.
