- How many files can a process hold open at one time?
- Does the system support realtime signals?
- What is the biggest value that can be stored in a variable of type int?
- How big an argument list can a program have?
- What is the maximum length of a pathname?
- 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.
- At run time on a particular implementation: The kernel may have been reconfigured to change a limit, for example. Alternatively, the application may have been com-piled on one system, but run on another system with different limits and options.
- From one file system to another: For example, traditional System V file systems allow a filename to be up to 14 bytes, while traditional BSD file systems and most native Linux file systems allow filenames of up to 255 bytes.
- Some limits and options can be determined at compile time. For example, the maximum value of an int is determined by the hardware architecture and compiler design choices. Such limits can be recorded in header files.
- Other limits and options may vary at run time. For such cases, SUSv3 defines three functions--sysconf(), pathconf(), and fpathconf()--that an application can call to check these implementation limits and options.
11 System Limits and Options
11.1 System Limits
11.2 Retrieving System Limits (and Options) at Run Time
11.3 Retrieving File-related Limits (and Options) at Run Time
11.4 Indeterminate Limits
11.5 System Options