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SYSCONF !!!SYSCONF NAME SYNOPSIS DESCRIPTION RETURN VALUE CONFORMING TO BUGS SEE ALSO ---- !!NAME sysconf - Get configuration information at runtime !!SYNOPSIS __#include __ ''name''__); __ !!DESCRIPTION __sysconf()__ provides a way for the application to determine values for system limits or options at runtime. The equivalent macros defined in ____ can only give conservative values; if an application wants to take advantage of values which may change, a call to __sysconf()__ can be made, which may yield more liberal results. For getting information about a particular file, see __fpathconf()__ or __pathconf()__. The following values are supported for ''name''. First, the POSIX.1 compatible values: ___SC_ARG_MAX__ The maximum length of the arguments to the __exec()__ family of functions; the corresponding macro is __ARG_MAX__. ___SC_CHILD_MAX__ The number of simultaneous processes per user id, the corresponding macro is ___POSIX_CHILD_MAX__. ___SC_CLK_TCK__ The number of clock ticks per second; the corresponding macro is __CLK_TCK__. ___SC_STREAM_MAX__ The maximum number of streams that a process can have open at any time. The corresponding POSIX macro is __STREAM_MAX__, the corresponding standard C macro is __FOPEN_MAX__. ___SC_TZNAME_MAX__ The maximum number of bytes in a timezone name, the corresponding macro is __TZNAME_MAX__. ___SC_OPEN_MAX__ The maximum number of files that a process can have open at any time, the corresponding macro is ___POSIX_OPEN_MAX__. ___SC_JOB_CONTROL__ This indicates whether POSIX - style job control is supported, the corresponding macro is ___POSIX_JOB_CONTROL__. ___SC_SAVED_IDS__ This indicates whether a process has a saved set-user-ID and a saved set-group-ID; the corresponding macro is ___POSIX_SAVED_IDS__. ___SC_VERSION__ indicates the year and month the POSIX.1 standard was approved in the format __YYYYMML__;__the__ value __199009L__ indicates the most recent revision, 1990. Next, the POSIX.2 values: ___SC_BC_BASE_MAX__ indicates the maximum ''obase'' value accepted by the bc(1) utility; the corresponding macro is __BC_BASE_MAX__. ___SC_BC_DIM_MAX__ indicates the maximum value of elements permitted in an array by bc(1); the corresponding macro is __BC_DIM_MAX__. ___SC_BC_SCALE_MAX__ indicates the maximum ''scale'' value allowed by bc(1); the corresponding macro is __BC_SCALE_MAX__. ___SC_BC_STRING_MAX__ indicates the maximum length of a string accepted by bc(1); the corresponding macro is __BC_STRING_MAX__. ___SC_COLL_WEIGHTS_MAX__ indicates the maximum numbers of weights that can be assigned to an entry of the __LC_COLLATE order__ keyword in the locale definition file; the corresponding macro is __COLL_WEIGHTS_MAX__. ___SC_EXPR_NEST_MAX__ is the maximum number of expressions which can be nested within parentheses by expr(1). The corresponding macro is __EXPR_NEST_MAX__. ___SC_LINE_MAX__ The maximum length of a utility's input line length, either from standard input or from a file. This includes length for a trailing newline. The corresponding macro is __LINE_MAX__. ___SC_RE_DUP_MAX__ The maximum number of repeated occurrences of a regular expression when the interval notation __{m,n}__ is used. The value of the corresponding macro is __RE_DUP_MAX__. ___SC_2_VERSION__ indicates the version of the POSIX.2 standard in the format of YYYYMML. The corresponding macro is __POSIX2_VERSION__. ___SC_2_DEV__ indicates whether the POSIX.2 C language development facilities are supported. The corresponding macro is __POSIX2_C_DEV__. ___SC_2_FORT_DEV__ indicates whether the POSIX.2 FORTRAN development utilities are supported. The corresponding macro is __POSIX2_FORT_RUN__. ___SC_2_FORT_RUN__ indicates whether the POSIX.2 FORTRAN runtime utilities are supported. The corresponding macro is __POSIX2_FORT_RUN__. ___SC_2_LOCALEDEF__ indicates whether the POSIX.2 creation of locates via localedef(1) is supported. The corresponding macro is ___POSIX2_LOCALEDEF__. ___SC_2_SW_DEV__ indicates whether the POSIX.2 software development utilities option is supported. The corresponding macro is __POSIX2_SW_DEV__. SUSv2 also lists ___SC_PAGESIZE _SC_PAGE_SIZE__ The size of a page (in bytes). These values also exist, but may not be standard. ___SC_PHYS_PAGES__ The number of pages of physical memory. Note that it is possible for the product of this value and the value of ___SC_PAGE_SIZE__ to overflow. ___SC_AVPHYS_PAGES__ The number of currently available pages of physical memory. !!RETURN VALUE The value returned is the value of the system resource, 1 if a queried option is available, 0 if it is not, or -1 on error. The variable ''errno'' is not set. !!CONFORMING TO POSIX.1, proposed POSIX.2 !!BUGS It is difficult to use __ARG_MAX__ because it is not specified how much of the argument space for __exec()__ is consumed by the user's environment variables. Some returned values may be huge; they are not suitable for allocating memory. POSIX.2 is not yet an approved standard; the information in this manpage is subject to change. !!SEE ALSO bc(1), expr(1), locale(1), fpathconf(3), pathconf(3) ----
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sysconf(3)
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