Chapter 11: System Limits and Options.........................................................................
Each UNIX implementation sets limits on various system features and resources,
and provides—or chooses not to provide—options defined in various standards.
Examples include the following:
z How many files can a process hold open at one time?
z Does the system support realtime signals?
z What is the largest value that can be stored in a variable of type int?
z How big an argument list can a program have?
z What is the maximum length of a pathname?
While we could hard-code assumed limits and options into an application, this
reduces portability, since limits and options may vary:
z Across UNIX implementations: Although limits and options may be fixed on an
individual implementation, they can vary from one UNIX implementation to
another. The maximum value that can be stored in an int is an example of such
a limit.
z At run time on a particular implementation: The kernel may have been reconfig-
ured to change a limit, for example. Alternatively, the application may have
been compiled on one system, but run on another system with different limits
and options.
