Unix Exit Status Code Reference

I always find myself constantly Googling the list of unix status codes (typically defined in `sysexits.h`).

0    # successful termination 
64   # base value for error messages 
64   # command line usage error 
65   # data format error 
66   # cannot open input     
67   # addressee unknown     
68   # host name unknown 
69   # service unavailable 
70   # internal software error 
71   # system error (e.g., can't fork) 
72   # critical OS file missing 
73   # can't create (user) output file 
74   # input/output error 
75   # temp failure; user is invited to retry 
76   # remote error in protocol 
77   # permission denied 
78   # configuration error