Fix command 'echo_file'.

src/gmic_stdlib.gmic

@@ -3551,7 +3551,8 @@ _display_warp : check "${1=15}>0"
 #@cli : Output specified message, appending it to specified output file.
 #@cli : (similar to 'echo' for specified output file stream).
 echo_file : skip "${2='\n'}"
-  ('"${2--1}\n"') ot. $1 rm.
+  l[] { it "$1" onfail 0 }
+  ('"${2--1}\n"':y) a[-2,-1] y ot. $1 rm.
 
 #@cli function1d : 0<=smoothness<=1,x0>=0,y0,x1>=0,y1,...,xn>=0,yn
 #@cli : Insert continuous 1D function from specified list of keypoints (xk,yk)