sysconf(2)                                                   sysconf(2)

  sysconf()

  NAME

    sysconf() - get configurable system variables

  SYNOPSIS

    #include 

    long sysconf (int name)

  DESCRIPTION

    This interface is defined by

    The sysconf(2) function provides a method for applications to determine
    the current value of a configurable system limit or option variable. The
    name argument specifies the system variable to be queried. Symbolic
    constants for each name value are found in the include file .

    The definitive list of symbolic constants is in the include file. As of
    this writing, the available values are as follows:
    sysconf() Name                       Description

    _SC_2_C_BIND                         Whether system provides POSIX.2 C
                                         language bindings

    _SC_2_C_DEV                          Whether system supports the POSIX.2
                                         C-Language Development Utilities
                                         Option

    _SC_2_CHAR_TERM                      Whether system supports at least one
                                         terminal type capable of supporting
                                         all operations described in POSIX.2

    _SC_2_FORT_RUN                       Whether system supports POSIX.2
                                         FORTRAN Runtime Utilities Option

    _SC_2_FORT_DEV                       Whether system supports POSIX.2
                                         FORTRAN Development Utilities Option

    _SC_2_LOCALEDEF                      Whether system supports the creation
                                         of locales

    _SC_2_SW_DEV                         Whether system supports POSIX.2
                                         Software Development Portability
                                         Utilities Option

    _SC_2_UPE                            Whether system supports POSIX.2 User
                                         Portability Utilities Option

    _SC_2_VERSION                        Version of ISO/IEC 9945 (POSIX
                                         1003.2) with which the system
                                         attempts to comply.

    _SC_ARG_MAX                          Maximum bytes of argument to exec().

    _SC_BC_BASE_MAX                      Maximum obase value allowed by bc

    _SC_BC_DIM_MAX                       Maximum number of elements in a bc
                                         array

    _SC_BC_SCALE_MAX                     Maximum scale value allowed by bc

    _SC_BC_STRING_MAX                    Maximum length of a string constant
                                         in bc

    _SC_CHILD_MAX                        Maximum number of simultaneous
                                         processes per user ID.

    _SC_CLK_TCK                          Number of micro-seconds per hz tick.

    _SC_COLL_WEIGHTS_MAX                 In a locale definition file, the
                                         maximum number of weights that can be
                                         assigned to the LC_COLLATE order
                                         keyword

    _SC_EXPR_NEST_MAX                    Maximum number of expressions that
                                         can be nested within parentheses by
                                         expr

    _SC_JOB_CONTROL                      Return 1 if job control is available
                                         on this system, otherwise -1.

    _SC_LINE_MAX                         Maximum length in bytes, including
                                         trailing newline, of an input line
                                         for a text-processing utility

    _SC_NGROUPS_MAX                      Maximum number of supplemental
                                         groups.

    _SC_OPEN_MAX                         Maximum number of open files per
                                         process.

    _SC_PAGE_SIZE                        The virtual memory page size. This is
                                         always 65536 (64 KB), regardless of
                                         the actual Windows page size.

    _SC_PAGESIZE                         The virtual memory page size. This is
                                         always 65536 (64 KB), regardless of
                                         the actual Windows page size.

    _SC_RE_DUP_MAX                       Maximum number of repetitions of a
                                         BRE allowed in \{m,n\} notation

    _SC_READER_WRITER_LOCKS              The version of IEEE Std 1003.1
                                         ("POSIX.1") and its Read-Write Locks
                                         option to which the system attempts
                                         to conform

    _SC_SAVED_IDS                        Returns 1 if saved set-group and
                                         saved set-user ID is available,
                                         otherwise -1.

    _SC_SPIN_LOCKS                       The version of IEEE Std 1003.1
                                         ("POSIX.1") and its Spin Locks option
                                         to which the system attempts to
                                         conform

    _SC_THREADS                          System supports POSIX threads.

    _SC_THREAD_ATTR_STACKADDR            System supports the stack address
                                         option for POSIX threads.

    _SC_THREAD_ATTR_STACKSIZE            System supports the stack size option
                                         for POSIX threads.

    _SC_THREAD_DESTRUCTOR_ITERATIONS     Maximum number attempts made to
                                         destroy a thread's thread-specific
                                         data.

    _SC_THREAD_KEYS_MAX                  Maximum number of data keys per
                                         process.

    _SC_THREAD_PRIORITY_SCHEDULING       System supports the priority
                                         scheduling for POSIX threads.

    _SC_THREAD_SAFE_FUNCTIONS            System supports thread-safe functions

    _SC_THREAD_STACK_MIN                 Minimum size in bytes of thread stack
                                         storage.

    _SC_THREAD_THREADS_MAX               Maximum number of threads within a
                                         process.

    _SC_TZNAME_MAX                       Minimum maximum number of types
                                         supported for the name of a timezone.

    _SC_VERSION                          The version of ISO/IEC 9945 (POSIX
                                         1003.1) with which the system
                                         attempts to comply.

  RETURN VALUES

    If the call to sysconf(2) is not successful, the function returns -1 and
    sets errno appropriately. If the variable is associated with functionality
    that isn't supported or if the variable is not valid, the function returns
    -1 and does not set errno

    Otherwise, the current variable value is returned.

  ERRORS

    The sysconf(2) function may fail and set errno for any of these errors:

    [EINVAL]
        The value of the name argument is invalid.

  USAGE NOTES

    The sysconf function is thread safe.

    The sysconf function is async-signal safe.