Linux file naming rules and command formats

Two special directories,..., represent the current directory and the parent directory of the current directory. Linux file naming rules and command formats

Linux file naming rules:
1) all characters except/are valid.
2) it is recommended that you do not use some special characters, such as space characters, tabs, escape characters, and characters such as @ # $.
3) avoid using. as the first character of a common file name.
4) case sensitive.

Linux command format:
Command-option parameter
Example: ls-la/etc
Note:
1) when there are multiple options, you can write them together.
2) two special directories,..., represent the current directory and the parent directory of the current directory.