The shell learns notes.

1. Semicolons separate multiple commands.

2. There are no spaces in the middle of the variable assignment.

3. When constructing pipelines, try to make the amount of data in each phase less. If the two tasks are not related to the order, then the operations that make the amount of data less can be done first.

4. Bit barrel/dev/null

Data uploaded to this file will be discarded by the system.

5./dev/tty

When you open this file, Unix automatically redirects it to a terminal. Especially useful when you have to enter manually.

The shell learns notes.