echo command takes two arguments. Both arguments are filenames.
The first argument must be the name of an existing file. The second argument
is the name of a file to be created. The command reads the contents of the first
file, transmits the contents to the controller, which then sends the contents back
to the computer where it is written to the second file. For example:
‘echo source destination’
This command will create a file called destination which upon command completion should have identical contents to source. This command is not very useful. It is intended for testing the integrity of the controller–computer link.