Question

You are writing a provisioning script that must create an application config file. The file needs to embed the value of the shell variable $APP_PORT while writing multiple lines to /etc/myapp/app.conf in a single command. Which construct correctly writes the block, with variable expansion, to the file?

Accepted Answer

cat << EOF > /etc/myapp/app.conf
listen_port=$APP_PORT
log_level=info
EOF

Answer

cat << 'EOF' > /etc/myapp/app.conf
listen_port=$APP_PORT
log_level=info
EOF

Answer

cat < EOF > /etc/myapp/app.conf
listen_port=$APP_PORT
log_level=info
EOF

Answer

echo << EOF >> /etc/myapp/app.conf listen_port=$APP_PORT log_level=info EOF