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7.6.25 USAGE( exit-code ) - Usage invocation macro

This macro invokes the procedure registered to display the usage text. Normally, this will be optionUsage from the AutoOpts library, but you may select another procedure by specifying usage = "proc_name" program attribute. This procedure must take two arguments first, a pointer to the option descriptor, and second the exit code. The macro supplies the option descriptor automatically. This routine is expected to call exit(3) with the provided exit code.

The optionUsage routine also behaves differently depending on the exit code:

EXIT_SUCCESS (the value zero)

It is assumed that full usage help has been requested. Consequently, more information is provided than when displaying usage and exiting with a non-zero exit code. Output will be sent to ‘stdout’ and the program will exit with a zero status code.

EX_USAGE (64)

The abbreviated usage will be printed to ‘stdout’ and the program will exit with a zero status code. EX_USAGE may or may not be 64. If your system provides ‘/usr/include/sysexits.h’ that has a different value, then that value will be used.

any other value

The abbreviated usage will be printed to stderr and the program will exit with the provided status code.


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