Intercept set function for interrupt processing intercept int (* func) int os9 F$ICPT Intercept instructs OS-9 to pass control to the function "func" when an interrupt (signal) is received by the current process. If the interrupt processing function has an argument, it will contain the value of the signal received. On return from "func", the process resumes at the point in the program where it was interrupted by the signal. "Interrupt()" is an alternative to the use of "signal()" to process interrupts. As an example, suppose we wish to ensure that a partially completed output file is deleted if an interrupt is received. The body of the program might include: char *temp_file = "temp"; /* name of temporary file */ int pn=0; /* path number */ int intrupt(); /* predeclaration */ ... intercept(intrupt); /* route interrupt processing */ pn = creat(temp_file,3); /* make a new file */ ... write(pn,string,count); /* write string to temp file */ ... close(pn); pn=0; ... The interrupt routine might be coded: intrupt(sig); { if (pn){ /* only done if pn refers to an open file */ close(pn); unlink(temp_file); /* delete */ } exit(sig); } "Intercept()" and "signal()" are mutually incompatible so that calls to both must not appear in the same program. The linker guards against this by giving an "entry name clash - _sigint" error if it is attempted. signal()