which form of @ is this?

Can someone explain to me which form of @ is this? This is running the sysCommand and if it fails, it prints the message. But I don’t see how functional form of amend is applying to this. How is @ being used here?

@[system; sysCommand; {"Failed to run command: ",x}]

thx

Hi Sam,

It is the monadic protected evaluation.

http://code.kx.com/wiki/JB:QforMortals/execution_control

Thanks Rory