The following example shows how a program might use SIGNAL ON to trap a command error in a program that copies a file. In this example, an error occurs because the name of a nonexistent file is stored in the variable File1. Processing jumps to the clause following the label ERROR:
/* example of error trap */ signal on error /* Set the trap. */ . . . ┌─── "COPY" file1 file2 /* When an error occurs... */ │ . │ . │ exit . └───error: /* ...REXX jumps to here */ say "Error" rc "at line" sigl say "Program cannot continue." exit /* and ends the program. */