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NetBSD 6.1.5 - man page for sysconf (netbsd section 3)

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SYSCONF(3)			   BSD Library Functions Manual 		       SYSCONF(3)

NAME
     sysconf -- get configurable system variables

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     long
     sysconf(int name);

DESCRIPTION
     This interface is defined by IEEE Std 1003.1-1988 (``POSIX.1'').  A far more complete inter-
     face is available using sysctl(3).

     The sysconf() 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 <unistd.h>.

     The available values are as follows:

     _SC_ARG_MAX
	     The maximum bytes of argument to execve(2).

     _SC_ATEXIT_MAX
	     The maximum number of functions that may be registered with atexit(3).

     _SC_BARRIERS
	     The version of IEEE Std 1003.1 (``POSIX.1'') and its Barriers option to which the
	     system attempts to conform, otherwise -1.

     _SC_CLOCK_SELECTION
	     Return the POSIX version the implementation of the Clock Selection Option on this
	     system conforms to, or -1 if unavailable.

     _SC_CHILD_MAX
	     The maximum number of simultaneous processes per user id.

     _SC_CLK_TCK
	     The number of clock ticks per second.

     _SC_FSYNC
	     Return 1 if the File Synchronization Option is available on this system, otherwise
	     -1.

     _SC_HOST_NAME_MAX
	     The maximum size of a hostname, including NULL.

     _SC_IOV_MAX
	     The maximum number of iovec structures that a process has available for use with
	     preadv(2), pwritev(2), readv(2), recvmsg(2), sendmsg(2) or writev(2).

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

     _SC_LOGIN_NAME_MAX
	     Returns the size of the storage required for a login name, in bytes, including the
	     terminating NUL.

     _SC_MAPPED_FILES
	     Return 1 if the Memory Mapped Files Option is available on this system, otherwise
	     -1.

     _SC_MEMLOCK
	     Return 1 if the Process Memory Locking Option is available on this system, otherwise
	     -1.

     _SC_MEMLOCK_RANGE
	     Return 1 if the Range Memory Locking Option is available on this system, otherwise
	     -1.

     _SC_MEMORY_PROTECTION
	     Return 1 if the Memory Protection Option is available on this system, otherwise -1.

     _SC_MONOTONIC_CLOCK
	     Return the POSIX version the implementation of the Monotonic Clock Option on this
	     system conforms to, or -1 if unavailable.

     _SC_NGROUPS_MAX
	     The maximum number of supplemental groups.

     _SC_OPEN_MAX
	     The maximum number of open files per process.

     _SC_PAGESIZE
	     The size of a system page in bytes.

     _SC_PASS_MAX
	     The maximum length of the password, not counting NULL.

     _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, otherwise -1.

     _SC_REGEXP
	     Return 1 if POSIX regular expressions are available on this system, otherwise -1.

     _SC_SEMAPHORES
	     The version of IEEE Std 1003.1 (``POSIX.1'') and its Semaphores option to which the
	     system attempts to conform, otherwise -1.

	     Availability of the Semaphores option depends on the P1003_1B_SEMAPHORE kernel
	     option.

     _SC_SHELL
	     Return 1 if POSIX shell is available on this system, 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, otherwise -1.

     _SC_STREAM_MAX
	     The minimum maximum number of streams that a process may have open at any one time.

     _SC_SYMLOOP_MAX
	     The maximum number of symbolic links that may be expanded in a path name.

     _SC_SYNCHRONIZED_IO
	     Return 1 if the Synchronized I/O Option is available on this system, otherwise -1.

     _SC_THREADS
	     The version of IEEE Std 1003.1 (``POSIX.1'') and its Threads option to which the
	     system attempts to conform, otherwise -1.

     _SC_TIMERS
	     The version of IEEE Std 1003.1 (``POSIX.1'') and its Timers option to which the sys-
	     tem attempts to conform, otherwise -1.

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

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

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

     _SC_XOPEN_SHM
	     Return 1 if the X/Open Portability Guide Issue 4, Version 2 (``XPG4.2'') Shared Mem-
	     ory option is available on this system, otherwise -1.

	     Availability of the Shared Memory option depends on the SYSVSHM kernel option.

     _SC_BC_BASE_MAX
	     The maximum ibase/obase values in the bc(1) utility.

     _SC_BC_DIM_MAX
	     The maximum array size in the bc(1) utility.

     _SC_BC_SCALE_MAX
	     The maximum scale value in the bc(1) utility.

     _SC_BC_STRING_MAX
	     The maximum string length in the bc(1) utility.

     _SC_COLL_WEIGHTS_MAX
	     The maximum number of weights that can be assigned to any entry of the LC_COLLATE
	     order keyword in the locale definition file.

     _SC_EXPR_NEST_MAX
	     The maximum number of expressions that can be nested within parenthesis by the
	     expr(1) utility.

     _SC_LINE_MAX
	     The maximum length in bytes of a text-processing utility's input line.

     _SC_RE_DUP_MAX
	     The maximum number of repeated occurrences of a regular expression permitted when
	     using interval notation.

     _SC_2_VERSION
	     The version of POSIX 1003.2 with which the system attempts to comply.

     _SC_2_C_BIND
	     Return 1 if the system's C-language development facilities support the C-Language
	     Bindings Option, otherwise -1.

     _SC_2_C_DEV
	     Return 1 if the system supports the C-Language Development Utilities Option, other-
	     wise -1.

     _SC_2_CHAR_TERM
	     Return 1 if the system supports at least one terminal type capable of all operations
	     described in POSIX 1003.2, otherwise -1.

     _SC_2_FORT_DEV
	     Return 1 if the system supports the FORTRAN Development Utilities Option, otherwise
	     -1.

     _SC_2_FORT_RUN
	     Return 1 if the system supports the FORTRAN Runtime Utilities Option, otherwise -1.

     _SC_2_LOCALEDEF
	     Return 1 if the system supports the creation of locales, otherwise -1.

     _SC_2_SW_DEV
	     Return 1 if the system supports the Software Development Utilities Option, otherwise
	     -1.

     _SC_2_UPE
	     Return 1 if the system supports the User Portability Utilities Option, otherwise -1.

     _SC_GETGR_R_SIZE_MAX
	     The minimum size of the buffer passed to getgrgid_r(3) and getgrnam_r(3).

     _SC_GETPW_R_SIZE_MAX
	     The minimum size of the buffer passed to getpwnam_r(3) and getpwuid_r(3).

     _SC_NPROCESSORS_CONF
	     The number of processors configured.

     _SC_NPROCESSORS_ONLN
	     The number of processors online (capable of running processes).

     _SC_PHYS_PAGES
	     The amount of physical memory on the system in _SC_PAGESIZE bytes.

RETURN VALUES
     If the call to sysconf is not successful, -1 is returned and errno is set appropriately.
     Otherwise, if the variable is associated with functionality that is not supported, -1 is
     returned and errno is not modified.  Otherwise, the current variable value is returned.

ERRORS
     The sysconf() function may fail and set errno for any of the errors specified for the
     library functions sysctl(3).  In addition, the following error may be reported:

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

SEE ALSO
     getconf(1), limits(3), sysctl(3)

STANDARDS
     The sysconf() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').  The constants
     _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are not part of the standard, but are provided
     by many systems.

HISTORY
     The sysconf function first appeared in 4.4BSD.

BUGS
     The value for _SC_STREAM_MAX is a minimum maximum, and required to be the same as ANSI C's
     FOPEN_MAX, so the returned value is a ridiculously small and misleading number.

BSD					 November 2, 2012				      BSD
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