What is "echo"

It is a command available on Unix that displays a text on the screen of a computer terminal. It is a command used in scripts to display messages on the screen or in a file. The command is also present on DOS, Linux, Mac OS, OS/2, and Windows.

Use in data logging:

It is common to use the echo in scripts enabled by cron.

    echo "Seu script está sendo executado agora" >> aviso.txt

The linux has a specific directory for storing logs, whose path is: /var/log/.