Heredoc reference

1. variable substitution, leading tab retained, overwrite file, echo to stdout

tee /path/to/file <<EOF
    ${variable}
EOF

1. no variable substitution, leading tab retained, overwrite file, echo to stdout

tee /path/to/file <<'EOF'
    ${variable}
EOF

1. variable substitution, leading tab removed, overwrite file, echo to stdout

tee /path/to/file <<-EOF
    ${variable}
EOF

1. variable substitution, leading tab retained, append to file, echo to stdout

tee -a /path/to/file <<EOF
    ${variable}
EOF

1. variable substitution, leading tab retained, overwrite file, no echo to stdout

tee /path/to/file <<EOF >/dev/null
${variable}
EOF

1. the above can be combined with sudo as well

sudo -u USER tee /path/to/file <<EOF
${variable}
EOF

Reference:

• https://stackoverflow.com/a/38731052/3151055
• https://unix.stackexchange.com/a/405254/269313