 | | UNIX signal handling used to be both simple to do and simple to explain—there was only one way to do things, and everyone followed it. However, as the need for more sophisticated signal handling increased, other ways of doing things evolved. As each new way was implemented, explaining things got harder—not only was there more to explain about how things worked, but it also became necessary to explain which methods were used for which situations. This problem has reached a peak in SVR4, which provides four different methods for handling signals: the original basic mechanism introduced in Version 7, the somewhat more robust mechanism introduced in SVR3, a compatibility library implementation of the Berkeley mechanism used by many vendors' operating systems, and, new to SVR4, the POSIX mechanism. | |
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