---

32.4.2 Constants for sysconf Parameters

Here are the symbolic constants for use as the parameter argument to sysconf. The values are all integer constants (more specifically, enumeration type values).

_SC_ARG_MAX ¶

Inquire about the parameter corresponding to ARG_MAX.

_SC_CHILD_MAX ¶

Inquire about the parameter corresponding to CHILD_MAX.

_SC_OPEN_MAX ¶

Inquire about the parameter corresponding to OPEN_MAX.

_SC_STREAM_MAX ¶

Inquire about the parameter corresponding to STREAM_MAX.

_SC_TZNAME_MAX ¶

Inquire about the parameter corresponding to TZNAME_MAX.

_SC_NGROUPS_MAX ¶

Inquire about the parameter corresponding to NGROUPS_MAX.

_SC_JOB_CONTROL ¶

Inquire about the parameter corresponding to _POSIX_JOB_CONTROL.

_SC_SAVED_IDS ¶

Inquire about the parameter corresponding to _POSIX_SAVED_IDS.

_SC_VERSION ¶

Inquire about the parameter corresponding to _POSIX_VERSION.

_SC_CLK_TCK ¶

Inquire about the number of clock ticks per second; see CPU Time Inquiry. The corresponding parameter CLK_TCK is obsolete.

_SC_CHARCLASS_NAME_MAX ¶

Inquire about the parameter corresponding to maximal length allowed for a character class name in an extended locale specification. These extensions are not yet standardized and so this option is not standardized as well.

_SC_REALTIME_SIGNALS ¶

Inquire about the parameter corresponding to _POSIX_REALTIME_SIGNALS.

_SC_PRIORITY_SCHEDULING ¶

Inquire about the parameter corresponding to _POSIX_PRIORITY_SCHEDULING.

_SC_TIMERS ¶

Inquire about the parameter corresponding to _POSIX_TIMERS.

_SC_ASYNCHRONOUS_IO ¶

Inquire about the parameter corresponding to _POSIX_ASYNCHRONOUS_IO.

_SC_PRIORITIZED_IO ¶

Inquire about the parameter corresponding to _POSIX_PRIORITIZED_IO.

_SC_SYNCHRONIZED_IO ¶

Inquire about the parameter corresponding to _POSIX_SYNCHRONIZED_IO.

_SC_FSYNC ¶

Inquire about the parameter corresponding to _POSIX_FSYNC.

_SC_MAPPED_FILES ¶

Inquire about the parameter corresponding to _POSIX_MAPPED_FILES.

_SC_MEMLOCK ¶

Inquire about the parameter corresponding to _POSIX_MEMLOCK.

_SC_MEMLOCK_RANGE ¶

Inquire about the parameter corresponding to _POSIX_MEMLOCK_RANGE.

_SC_MEMORY_PROTECTION ¶

Inquire about the parameter corresponding to _POSIX_MEMORY_PROTECTION.

_SC_MESSAGE_PASSING ¶

Inquire about the parameter corresponding to _POSIX_MESSAGE_PASSING.

_SC_SEMAPHORES ¶

Inquire about the parameter corresponding to _POSIX_SEMAPHORES.

_SC_SHARED_MEMORY_OBJECTS ¶

Inquire about the parameter corresponding to
_POSIX_SHARED_MEMORY_OBJECTS.

_SC_AIO_LISTIO_MAX ¶

Inquire about the parameter corresponding to _POSIX_AIO_LISTIO_MAX.

_SC_AIO_MAX ¶

Inquire about the parameter corresponding to _POSIX_AIO_MAX.

_SC_AIO_PRIO_DELTA_MAX ¶

Inquire the value by which a process can decrease its asynchronous I/O priority level from its own scheduling priority. This corresponds to the run-time invariant value AIO_PRIO_DELTA_MAX.

_SC_DELAYTIMER_MAX ¶

Inquire about the parameter corresponding to _POSIX_DELAYTIMER_MAX.

_SC_MQ_OPEN_MAX ¶

Inquire about the parameter corresponding to _POSIX_MQ_OPEN_MAX.

_SC_MQ_PRIO_MAX ¶

Inquire about the parameter corresponding to _POSIX_MQ_PRIO_MAX.

_SC_RTSIG_MAX ¶

Inquire about the parameter corresponding to _POSIX_RTSIG_MAX.

_SC_SEM_NSEMS_MAX ¶

Inquire about the parameter corresponding to _POSIX_SEM_NSEMS_MAX.

_SC_SEM_VALUE_MAX ¶

Inquire about the parameter corresponding to _POSIX_SEM_VALUE_MAX.

_SC_SIGQUEUE_MAX ¶

Inquire about the parameter corresponding to _POSIX_SIGQUEUE_MAX.

_SC_TIMER_MAX ¶

Inquire about the parameter corresponding to _POSIX_TIMER_MAX.

_SC_PII ¶

Inquire about the parameter corresponding to _POSIX_PII.

_SC_PII_XTI ¶

Inquire about the parameter corresponding to _POSIX_PII_XTI.

_SC_PII_SOCKET ¶

Inquire about the parameter corresponding to _POSIX_PII_SOCKET.

_SC_PII_INTERNET ¶

Inquire about the parameter corresponding to _POSIX_PII_INTERNET.

_SC_PII_OSI ¶

Inquire about the parameter corresponding to _POSIX_PII_OSI.

_SC_SELECT ¶

Inquire about the parameter corresponding to _POSIX_SELECT.

_SC_UIO_MAXIOV ¶

Inquire about the parameter corresponding to _POSIX_UIO_MAXIOV.

_SC_PII_INTERNET_STREAM ¶

Inquire about the parameter corresponding to _POSIX_PII_INTERNET_STREAM.

_SC_PII_INTERNET_DGRAM ¶

Inquire about the parameter corresponding to _POSIX_PII_INTERNET_DGRAM.

_SC_PII_OSI_COTS ¶

Inquire about the parameter corresponding to _POSIX_PII_OSI_COTS.

_SC_PII_OSI_CLTS ¶

Inquire about the parameter corresponding to _POSIX_PII_OSI_CLTS.

_SC_PII_OSI_M ¶

Inquire about the parameter corresponding to _POSIX_PII_OSI_M.

_SC_T_IOV_MAX ¶

Inquire the value of the value associated with the T_IOV_MAX variable.

_SC_THREADS ¶

Inquire about the parameter corresponding to _POSIX_THREADS.

_SC_THREAD_SAFE_FUNCTIONS ¶

Inquire about the parameter corresponding to
_POSIX_THREAD_SAFE_FUNCTIONS.

_SC_GETGR_R_SIZE_MAX ¶

Inquire about the parameter corresponding to _POSIX_GETGR_R_SIZE_MAX.

_SC_GETPW_R_SIZE_MAX ¶

Inquire about the parameter corresponding to _POSIX_GETPW_R_SIZE_MAX.

_SC_LOGIN_NAME_MAX ¶

Inquire about the parameter corresponding to _POSIX_LOGIN_NAME_MAX.

_SC_TTY_NAME_MAX ¶

Inquire about the parameter corresponding to _POSIX_TTY_NAME_MAX.

_SC_THREAD_DESTRUCTOR_ITERATIONS ¶

Inquire about the parameter corresponding to _POSIX_THREAD_DESTRUCTOR_ITERATIONS.

_SC_THREAD_KEYS_MAX ¶

Inquire about the parameter corresponding to _POSIX_THREAD_KEYS_MAX.

_SC_THREAD_STACK_MIN ¶

Inquire about the parameter corresponding to _POSIX_THREAD_STACK_MIN.

_SC_THREAD_THREADS_MAX ¶

Inquire about the parameter corresponding to _POSIX_THREAD_THREADS_MAX.

_SC_THREAD_ATTR_STACKADDR ¶

Inquire about the parameter corresponding to
a _POSIX_THREAD_ATTR_STACKADDR.

_SC_THREAD_ATTR_STACKSIZE ¶

Inquire about the parameter corresponding to
_POSIX_THREAD_ATTR_STACKSIZE.

_SC_THREAD_PRIORITY_SCHEDULING ¶

Inquire about the parameter corresponding to _POSIX_THREAD_PRIORITY_SCHEDULING.

_SC_THREAD_PRIO_INHERIT ¶

Inquire about the parameter corresponding to _POSIX_THREAD_PRIO_INHERIT.

_SC_THREAD_PRIO_PROTECT ¶

Inquire about the parameter corresponding to _POSIX_THREAD_PRIO_PROTECT.

_SC_THREAD_PROCESS_SHARED ¶

Inquire about the parameter corresponding to _POSIX_THREAD_PROCESS_SHARED.

_SC_2_C_DEV ¶

Inquire about whether the system has the POSIX.2 C compiler command, c89.

_SC_2_FORT_DEV ¶

Inquire about whether the system has the POSIX.2 Fortran compiler command, fort77.

_SC_2_FORT_RUN ¶

Inquire about whether the system has the POSIX.2 asa command to interpret Fortran carriage control.

_SC_2_LOCALEDEF ¶

Inquire about whether the system has the POSIX.2 localedef command.

_SC_2_SW_DEV ¶

Inquire about whether the system has the POSIX.2 commands ar, make, and strip.

_SC_BC_BASE_MAX ¶

Inquire about the maximum value of obase in the bc utility.

_SC_BC_DIM_MAX ¶

Inquire about the maximum size of an array in the bc utility.

_SC_BC_SCALE_MAX ¶

Inquire about the maximum value of scale in the bc utility.

_SC_BC_STRING_MAX ¶

Inquire about the maximum size of a string constant in the bc utility.

_SC_COLL_WEIGHTS_MAX ¶

Inquire about the maximum number of weights that can necessarily be used in defining the collating sequence for a locale.

_SC_EXPR_NEST_MAX ¶

Inquire about the maximum number of expressions nested within parentheses when using the expr utility.

_SC_LINE_MAX ¶

Inquire about the maximum size of a text line that the POSIX.2 text utilities can handle.

_SC_EQUIV_CLASS_MAX ¶

Inquire about the maximum number of weights that can be assigned to an entry of the LC_COLLATE category ‘order’ keyword in a locale definition. The GNU C Library does not presently support locale definitions.

_SC_VERSION ¶

Inquire about the version number of POSIX.1 that the library and kernel support.

_SC_2_VERSION ¶

Inquire about the version number of POSIX.2 that the system utilities support.

_SC_PAGESIZE ¶

Inquire about the virtual memory page size of the machine. getpagesize returns the same value (see How to get information about the memory subsystem?).

_SC_NPROCESSORS_CONF ¶

Inquire about the number of configured processors.

_SC_NPROCESSORS_ONLN ¶

Inquire about the number of processors online.

_SC_PHYS_PAGES ¶

Inquire about the number of physical pages in the system.

_SC_AVPHYS_PAGES ¶

Inquire about the number of available physical pages in the system.

_SC_ATEXIT_MAX ¶

Inquire about the number of functions which can be registered as termination functions for atexit; see Cleanups on Exit.

_SC_XOPEN_VERSION ¶

Inquire about the parameter corresponding to _XOPEN_VERSION.

_SC_XOPEN_XCU_VERSION ¶

Inquire about the parameter corresponding to _XOPEN_XCU_VERSION.

_SC_XOPEN_UNIX ¶

Inquire about the parameter corresponding to _XOPEN_UNIX.

_SC_XOPEN_REALTIME ¶

Inquire about the parameter corresponding to _XOPEN_REALTIME.

_SC_XOPEN_REALTIME_THREADS ¶

Inquire about the parameter corresponding to _XOPEN_REALTIME_THREADS.

_SC_XOPEN_LEGACY ¶

Inquire about the parameter corresponding to _XOPEN_LEGACY.

_SC_XOPEN_CRYPT ¶

Inquire about the parameter corresponding to _XOPEN_CRYPT.

_SC_XOPEN_ENH_I18N ¶

Inquire about the parameter corresponding to _XOPEN_ENH_I18N.

_SC_XOPEN_SHM ¶

Inquire about the parameter corresponding to _XOPEN_SHM.

_SC_XOPEN_XPG2 ¶

Inquire about the parameter corresponding to _XOPEN_XPG2.

_SC_XOPEN_XPG3 ¶

Inquire about the parameter corresponding to _XOPEN_XPG3.

_SC_XOPEN_XPG4 ¶

Inquire about the parameter corresponding to _XOPEN_XPG4.

_SC_CHAR_BIT ¶

Inquire about the number of bits in a variable of type char.

_SC_CHAR_MAX ¶

Inquire about the maximum value which can be stored in a variable of type char.

_SC_CHAR_MIN ¶

Inquire about the minimum value which can be stored in a variable of type char.

_SC_INT_MAX ¶

Inquire about the maximum value which can be stored in a variable of type int.

_SC_INT_MIN ¶

Inquire about the minimum value which can be stored in a variable of type int.

_SC_LONG_BIT ¶

Inquire about the number of bits in a variable of type long int.

_SC_WORD_BIT ¶

Inquire about the number of bits in a variable of a register word.

_SC_MB_LEN_MAX ¶

Inquire the maximum length of a multi-byte representation of a wide character value.

_SC_NZERO ¶

Inquire about the value used to internally represent the zero priority level for the process execution.

SC_SSIZE_MAX ¶

Inquire about the maximum value which can be stored in a variable of type ssize_t.

_SC_SCHAR_MAX ¶

Inquire about the maximum value which can be stored in a variable of type signed char.

_SC_SCHAR_MIN ¶

Inquire about the minimum value which can be stored in a variable of type signed char.

_SC_SHRT_MAX ¶

Inquire about the maximum value which can be stored in a variable of type short int.

_SC_SHRT_MIN ¶

Inquire about the minimum value which can be stored in a variable of type short int.

_SC_UCHAR_MAX ¶

Inquire about the maximum value which can be stored in a variable of type unsigned char.

_SC_UINT_MAX ¶

Inquire about the maximum value which can be stored in a variable of type unsigned int.

_SC_ULONG_MAX ¶

Inquire about the maximum value which can be stored in a variable of type unsigned long int.

_SC_USHRT_MAX ¶

Inquire about the maximum value which can be stored in a variable of type unsigned short int.

_SC_NL_ARGMAX ¶

Inquire about the parameter corresponding to NL_ARGMAX.

_SC_NL_LANGMAX ¶

Inquire about the parameter corresponding to NL_LANGMAX.

_SC_NL_MSGMAX ¶

Inquire about the parameter corresponding to NL_MSGMAX.

_SC_NL_NMAX ¶

Inquire about the parameter corresponding to NL_NMAX.

_SC_NL_SETMAX ¶

Inquire about the parameter corresponding to NL_SETMAX.

_SC_NL_TEXTMAX ¶

Inquire about the parameter corresponding to NL_TEXTMAX.