rm and cp command should use option -r to distinguish file and directory. I think it means that they operate file and directory in a different way? However, mv command dosen't need it. This my problem. I want to understand how they work and their differences.And also, i want to know where do I go to find the answer the next time I have a similar problem?

My english is poor. Please forgive me if there are any mistakes. Any answer maybe helpful. Thanks.

CodePudding user response：

You may picture a directory as a "list" of what it actually contains (rather than a physical folder).

When you move a directory to another place using mv, you simply need to move the reference to this list on the disk, the content remaining unchanged.

rm and cp, however, need to browse this list because each item inside it need to be processed individually. Thus the -r if they contain subdirectories.

CodePudding user response：

If you have files in your folder and you want to copy or move it, you need to do the -r. It means recursive, it copys/moves the folder and also the files inside the folder.

When you have a folder without any files inside, you don't need to put that -r in the code, because the folder is empty.