history

Definition

A command that prints a numbered list of the previously executed commands stored in the user's shell history file.

Explain Like I'm New

The 'What did I just type 5 minutes ago?' command. It remembers everything you've typed so you don't have to memorize complex commands.

Real World Example

You ran a massive, complex Docker command yesterday but forgot it. You type `history | grep docker`. The terminal searches your past commands and prints out the exact command you used, saving you 20 minutes of Googling.

Common Use Cases

•Recalling complex commands
•Security auditing (seeing what a user typed)

Interview Questions

basic

How can you re-run a specific command from your history without retyping it (e.g., command number 105)?

intermediate

If you type a password directly into a command (like `mysql -u root -p1234`), is it saved in the history file?

Flash Cards

Question

Re-run by number?

Click to reveal answer

Answer

Type an exclamation mark followed by the number: `!105`.

Question

Is password saved?

Click to reveal answer

Answer

Yes! This is a massive security risk. Passwords passed as command-line arguments are stored in plain text in the `~/.bash_history` file. You should always use interactive password prompts.