tee

The tee command reads from standard input and writes to standard output and one or more files simultaneously. It is useful for logging the output of a command while still viewing it on the terminal.

Basic Syntax

tee [OPTION]... [FILE]...

Common Options

Option	Description
-a, --append	Append to the given files, do not overwrite.
-i, --ignore-interrupts	Ignore interrupt signals.

Real-world Examples

1. Save command output to a file and display it:

   ls -l | tee output.txt

2. Append to a file instead of overwriting:

   echo "New log entry" | tee -a logfile.txt

3. Write output to multiple files:

   echo "Test" | tee file1.txt file2.txt file3.txt

4. Use with sudo to write to a protected file:

   echo "127.0.0.1 mysite.local" | sudo tee -a /etc/hosts