I have taken Barmar's advice and the automatic backup works. Also, I redirect the output to sys:null-stream because I don't need it. (si:com-copy-file #p"dave:>jiang>**>*.*.newest" #p"dom:>users>jiang>**>*.*.*" :create-directories :yes :output-destination '(sys:null-stream)) Thank you all who helped me. -- Tao Jiang Swiss Federal Inst. of Tech., Lausanne