Microsoft DOS echo command
Echo is used to repeat the text typed in back to the screen and can be used to echo to a peripheral on the computer, such as a COM port.
The echo command is an internal command that is available in the below Microsoft operating systems.
Displays messages, or turns command-echoing on or off.
ECHO [ON | OFF]
Type ECHO without parameters to display the current echo setting.
echo ata > com1
Depending if your modem was on com1, this would make the modem try responding and you should hear some squealing from the modem. To stop the squealing, type echo atz > com1.
echo this is a test > test.bat
This would put in the file test.bat "echo this is a test", then whenever you type in test, it would type in echo this is a test.
echo this is an example >> test.txt
In the above example, this would echo "this is an example" then using >> it would append that text into the test.txt file.
echo testing the echo string
This would type on your screen, testing the echo string, and then take you back to the prompt.