Linux Terminal Command: tee

The tee command is an essential tool in Text Processing & Piping. In this tutorial, we will explore what tee does, look at everyday examples, and cover advanced options to supercharge your command-line workflow.

Concept & Explanation

The tee command duplicates the output stream, saving it to files while printing it to standard output.

Common Options & Syntax

tee [options] [arguments]

Here are the most common flags used with tee:

• Simple Usage: Basic default commands.
• Detailed View: Shows diagnostic information.
• Advanced Actions: Can chain parameters for scripting.

1. Interactive Example (Simple)

Here is how most people run the command:

# Example
ls -l | tee file_list.txt

What it does: Saves the list of files to ‘file_list.txt’ and prints it to the screen.

2. Power-User Example (Advanced)

For scripting and advanced diagnostics, use this configuration:

# Advanced
echo '127.0.0.1 db.local' | sudo tee -a /etc/hosts

What it does: Appends (-a) the hostname setting to /etc/hosts using sudo, letting you write to root-owned files from regular user pipes.

⚙️ Warning & Common Pitfalls

[!WARNING] Standard redirection sudo echo '...' >> /etc/hosts fails because redirection is executed by the shell without sudo privileges. Using tee resolves this safely.

🔗 Related Commands

Here are some related posts on cli_tty1 you might want to check out:

• sudo : Execute a command as another user (typically superuser).