gawk: Exit Status

 
 2.6 'gawk''s Exit Status
 ========================
 
 If the 'exit' statement is used with a value (SeeExit Statement),
 then 'gawk' exits with the numeric value given to it.
 
    Otherwise, if there were no problems during execution, 'gawk' exits
 with the value of the C constant 'EXIT_SUCCESS'.  This is usually zero.
 
    If an error occurs, 'gawk' exits with the value of the C constant
 'EXIT_FAILURE'.  This is usually one.
 
    If 'gawk' exits because of a fatal error, the exit status is two.  On
 non-POSIX systems, this value may be mapped to 'EXIT_FAILURE'.