Use BASH here documents whenever you need a multi-line text inside redirection.
Create or replace a file with a multi-line content.
$ tee /tmp/file << DELIMITER_KEYWORD line 1 line 2 line 3 DELIMITER_KEYWORD
line 1 line 2 line 3
Append a multi-line content to a file
$ tee --append /tmp/file << EOT line 4 line 5 EOT
line 4 line 5
Inspect created file.
$ cat /tmp/file
line 1 line 2 line 3 line 4 line 5
Use sudo whenever you need to gain elevated privileges.
$ sudo tee /tmp/hosts << EOTEE 172.16.254.254 desktop EOTEE
Variable expansion and command substitution is performed by default.
$ tee /tmp/varaible_values << EOF $USER $SHELL $(echo $HOME) \$HOME EOF
milosz /bin/bash /home/milosz $HOME
Quote the delimiter keyword to prevent variable expansion and command substitution.
$ tee /tmp/varaible_names << 'EOF' $USER $SHELL $(echo $HOME) \$HOME EOF
$USER $SHELL $(echo $HOME) \$HOME
Using here documents can look out of place inside shell scripts, so you can use
<<- redirection operator to strip leading tab characters.
if test -v HOME; then tee /tmp/home <<- EOF $HOME EOF fi
$ cat /tmp/home
This is a very basic knowledge, but still worth a reading. There are things like
cat overuse or similar habits that I am still trying to get rid of. The best thing I can do is to write it down and stick to it.