tee.md

Write to file and display to stdout

command | tee file.out
command | tee A.out B.out C.out 	# multiple files
command | tee -a file.out 		    # append mode

command 2>&1 | tee file.out       # both stdout and stderr are written to a file and displayed
command |& tee file.out           # equivalent but use |& operator introduced in bash 4

Combine with sudo

# Will fail because redirection is outside of sudo scope
sudo echo "newline" > /etc/file.conf

# Instead, use tee
echo "newline" | sudo tee -a /etc/file.conf