The Terminal Security Vector
Every time you type a command into an Ubuntu Linux terminal, the Bash shell meticulously records it in a hidden history file (~/.bash_history). This feature is incredibly useful for recalling complex commands using the up arrow key. However, if you have accidentally typed a plaintext password, an API key, or a sensitive database credential directly into the terminal, that highly classified information is now permanently stored in clear text on the hard drive, vulnerable to anyone who gains access to your user account.
How to Clear the Bash History
You can force the system to immediately purge its memory of your recent commands, protecting your sensitive inputs.
1. Open your terminal application or connect to your server via SSH.
2. To clear the active history cache from your current, live terminal session, execute the following command:
history -c
3. However, the commands are still saved in the physical file on the hard drive. To force the newly cleared session to overwrite the physical file, execute the write command:
history -w
4. Alternatively, if you want to completely obliterate the physical file itself to guarantee absolute deletion, you can delete the hidden text file directly:
rm ~/.bash_history
Once deleted, the shell will simply generate a new, blank history file the next time you log in, ensuring your previous indiscretions are completely erased.