C Library Functions sysconf(3C) NAME sysconf - get configurable system variables SYNOPSIS #include long sysconf(int name); DESCRIPTION The sysconf() function provides a method for an application to determine the current value of a configurable system limit or option (variable). The _n_a_m_e argument represents the system variable to be queried. The following table lists the minimal set of system variables from and that can be returned by sysconf() and the symbolic constants defined in that are the corresponding values used for _n_a_m_e on the SPARC and x86 platforms. Name Return Value Meaning _SC_2_C_BIND _POSIX2_C_BIND Supports the C language binding option _SC_2_C_DEV _POSIX2_C_DEV Supports the C language development utilities option _SC_2_C_VERSION _POSIX2_C_VERSION Integer value indicating version of ISO POSIX-2 standard (Commands) _SC_2_CHAR_TERM _POSIX2_CHAR_TERM Supports at least one terminal _SC_2_FORT_DEV _POSIX2_FORT_DEV Supports FORTRAN Development Utili- ties Option _SC_2_FORT_RUN _POSIX2_FORT_RUN Supports FORTRAN Run-time Utili- ties Option _SC_2_LOCALEDEF _POSIX2_LOCALEDEF Supports the creation of locales by the localedef utility _SC_2_SW_DEV _POSIX2_SW_DEV Supports the Software Development Utility Option _SC_2_UPE _POSIX2_UPE Supports the User Portability Util- ities Option _SC_2_VERSION _POSIX2_VERSION Integer value indicating version of ISO POSIX-2 standard (C language binding) _SC_AIO_LISTIO_MAX AIO_LISTIO_MAX Max number of I/O operations in a single list I/O call supported _SC_AIO_MAX AIO_MAX Max number of outstanding asynchro- nous I/O operations supported SC_AIO_PRIO_DELTA_ MAX AIO_PRIO_DELTA_MAX Max amount by which a process can decrease its asynchronous I/O priority level from its own scheduling priority SunOS 5.7 Last change: 10 Mar 1998 1 C Library Functions sysconf(3C) _SC_ARG_MAX ARG_MAX Max size of argv[] plus envp[] _SC_ASYNCHRONOUS_IO _POSIX_ASYNCHRONOUS_ IO Supports Asynchronous I/O _SC_ATEXIT_MAX ATEXIT_MAX Max number of functions that may be registered with atexit() _SC_AVPHYS_PAGES Number physical memory pages not currently in use by system _SC_BC_BASE_MAX BC_BASE_MAX Maximum _o_b_a_s_e values allowed by the bc utility _SC_BC_DIM_MAX BC_DIM_MAX Max number of elements permitted in array by bc _SC_BC_SCALE_MAX BC_SCALE_MAX Max _s_c_a_l_e value allowed by bc _SC_BC_STRING_MAX BC_STRING_MAX Max length of string constant allowed by bc _SC_CHILD_MAX CHILD_MAX Max processes allowed to a UID _SC_CLK_TCK CLK_TCK Ticks per second (clock_t) _SC_COLL_WEIGHTS_MAX COLL_WEIGHTS_MAX Max number of weights that can be assigned to entry of the LC_COLLATE order keyword in locale definition file _SC_DELAYTIMER_MAX DELAYTIMER_MAX Max number of timer expiration over- runs _SC_EXPR_NEST_MAX EXPR_NEST_MAX Max number of expressions that can be listed within parentheses by the expr utility _SC_FSYNC _POSIX_FSYNC Supports File Synchronization _SC_GETGR_R_SIZE_MAX NSS_BUFLEN_GROUP Max size of group entry buffer _SC_GETPW_R_SIZE_MAX NSS_BUFLEN_PASSWD Max size of password entry buffer _SC_IOV_MAX IOV_MAX Max number of iovec structures that one process has available for use with readv() and writev() _SC_JOB_CONTROL _POSIX_JOB_CONTROL Job control supported _SC_LINE_MAX LINE_MAX Max length of input line _SC_LOGIN_NAME_MAX LOGNAME_MAX + 1 Max length of login name. _SC_LOGNAME_MAX LOGNAME_MAX _SC_MAPPED_FILES _POSIX_MAPPED_FILES Supports Memory Mapped Files SunOS 5.7 Last change: 10 Mar 1998 2 C Library Functions sysconf(3C) _SC_MEMLOCK _POSIX_MEMLOCK Supports Process Memory Locking. _SC_MEMLOCK_RANGE _POSIX_MEMLOCK_RANGE Supports Range Memory Locking. _SC_MEMORY_ PROTECTION _POSIX_MEMORY_ PROTECTION Supports Memory Protec- tion. _SC_MESSAGE_PASSING _POSIX_MESSAGE_ PASSING Supports Message Pass- ing. _SC_MQ_OPEN_MAX MQ_OPEN_MAX Max number of open message queues a process may hold. _SC_MQ_PRIO_MAX MQ_PRIO_MAX Max number of message priorities sup- ported _SC_NGROUPS_MAX NGROUPS_MAX Max simultaneous groups to which one may belong _SC_NPROCESSORS_CONF Number of processors configured _SC_NPROCESSORS_ONLN Number of processors online _SC_OPEN_MAX OPEN_MAX Max open files per process _SC_PAGESIZE PAGESIZE System memory page size _SC_PAGE_SIZE PAGESIZE Same as _SC_PAGESIZE _SC_PASS_MAX PASS_MAX Max number of significant bytes in a password _SC_PHYS_PAGES Total number of pages of physical memory in system _SC_PRIORITIZED_IO _POSIX_PRIORITIZED_IO Supports Prioritized I/O _SC_PRIORITY_ SCHEDULING _POSIX_PRIORITY_ SCHEDULING Supports Process Schedul- ing SunOS 5.7 Last change: 10 Mar 1998 3 C Library Functions sysconf(3C) _SC_RE_DUP_MAX RE_DUP_MAX Max number of repeated _SC_REALTIME_SIGNALS _POSIX_REALTIME_ SIGNALS Supports Realtime Sig- nals. _SC_RTSIG_MAX RTSIG_MAX Max number of realtime signals reserved for application use _SC_SAVED_IDS _POSIX_SAVED_IDS Saved IDs (seteuid()) supported? _SC_SEM_NSEMS_MAX SEM_NSEMS_MAX Max number of semaphores that a process may have. _SC_SEM_VALUE_MAX SEM_VALUE_MAX Max value a semaphore may have _SC_SEMAPHORES _POSIX_SEMAPHORES Supports Semaphores _SC_SHARED_MEMORY_ OBJECTS _POSIX_SHARED_MEMORY_ OBJECTS Supports Shared MemoryOb- jects _SC_SIGQUEUE_MAX SIGQUEUE_MAX Max number of queued signals a pro- cess may send and have pending at receiver(s) at a time. _SC_STREAM_MAX STREAM_MAX Number of streams one processed can have open at a time _SC_SYNCHRONIZED_ IO _POSIX_SYNCHRONIZED_ IO Supports Synchronized I/O. _SC_THREAD_ATTR_ STACKADDR _POSIX_THREAD_ATTR_ STACKADDR Supports Thread Stack Address Attribute option SunOS 5.7 Last change: 10 Mar 1998 4 C Library Functions sysconf(3C) _SC_THREAD_ATTR_ STACKSIZE _POSIX_THREAD_ATTR_ STACKSIZE Supports Thread Stack Size Attri- bute option _SC_THREAD_DESTRUCTOR_ ITERATIONS PTHREAD_DESTRUCTOR_ ITERATIONS Number attempts made to destroy thread- specific data on thread exit _SC_THREAD_KEYS_MAX PTHREAD_KEYS_MAX Max number of data keys per process _SC_THREAD_PRIO_ INHERIT _POSIX_THREAD_PRIO_ INHERIT Supports Priority Inheritance option _SC_THREAD_PRIO_ PROTECT _POSIX_THREAD_PRIO_ PROTECT Supports Priority Protection option _SC_THREAD_PRIORITY_ SCHEDULING Supports Thread Execution Schedul- _POSIX_THREAD_PRIORITY_ ing option SCHEDULING _SC_THREAD_PROCESS_ SHARED _POSIX_THREAD_PROCESS_ SHARED T{ Supports Process-Shared Synchronization option SunOS 5.7 Last change: 10 Mar 1998 5 C Library Functions sysconf(3C) T} _SC_THREAD_SAFE_ FUNCTIONS _POSIX_THREAD_SAFE_ FUNCTIONS T{ Supports Thread-Safe Functions option T} _SC_THREAD_STACK_MIN PTHREAD_STACK_MIN T{ Min byte size of thread stack storage T} _SC_THREAD_THREADS_ MAX PTHREAD_THREADS_ MAX Max number of threads per pro- cess _SC_THREADS _POSIX_THREADS Supports Threads option _SC_TIMER_MAX TIMER_MAX Max number of timers per process _SC_TIMERS _POSIX_TIMERS Supports Timers _SC_TTY_NAME_MAX TTYNAME_MAX Max length of tty dev- ice name _SC_TZNAME_MAX TZNAME_MAX T{ Max number of bytes supported for name of a time zone T} _SC_VERSION _POSIX_VERSION T{ POSIX.1 version supported occurrences of a regular expres- sion permitted when using the interval notation \{_m,_n\} T} _SC_XBS5_ILP32_OFF32 _XBS_ILP32_OFF32 T{ Supports X/Open ILP32 w/32-bit offset build environ- ment T} _SC_XBS5_ILP32_OFFBIG _XBS5_ILP32_OFFBIG T{ Supports X/Open LP32 w/64-bit offset build environ- ment T} _SC_XBS5_LP64_OFF64 _XBS5_LP64_OFF64 T{ Supports X/Open LP64, 64-bit offset build SunOS 5.7 Last change: 10 Mar 1998 6 C Library Functions sysconf(3C) environ- ment T} _SC_XBS5_LPBIG_OFFBIG _XBS5_LP64_OFF64 Same as _SC_XBS5_LP64_OFF64 _SC_XOPEN_CRYPT _XOPEN_CRYPT T{ Supports X/Open Encryption Feature Group T} _SC_XOPEN_ENH_I18N _XOPEN_ENH_I18N T{ Supports X/Open Enhanced Internationalization Feature Group T} _SC_XOPEN_LEGACY _XOPEN_LEGACY T{ Supports X/Open Legacy Feature Group T} _SC_XOPEN_REALTIME _XOPEN_REALTIME T{ Supports X/Open POSIX Realtime Feature Group T} _SC_XOPEN_REALTIME_ THREADS _XOPEN_REALTIME_ THREADS T{ Supports X/Open POSIX Reatime Threads Feature Group T} _SC_XOPEN_SHM _XOPEN_SHM T{ Supports X/Open Shared Memory Feature Group T} _SC_XOPEN_UNIX _XOPEN_UNIX T{ Supports X/Open CAE Specification, August 1994, System Interfaces and Headers, Issue 4, Version 2 T} _SC_XOPEN_VERSION _XOPEN_VERSION T{ Integer value indicating version of X/Open Portability Guide to which implementation conforms T} _SC_XOPEN_XCU_VERSION _XOPEN_XCU_VERSION T{ Integer value indicating version of XCU specification to which implementation conforms T} RETURN VALUES SunOS 5.7 Last change: 10 Mar 1998 7 C Library Functions sysconf(3C) Upon successful completion, sysconf() returns the current variable value on the system. The value returned will not be more restrictive than the corresponding value described to the application when it was compiled with the implementation's , or . The value will not change during the lifetime of the calling process. If _n_a_m_e is an invalid value, sysconf() returns -1 and sets errno to indicate the error. If the variable corresponding to _n_a_m_e is associated with functionality that is not sup- ported by the system, sysconf() returns -1 without changing the value of _e_r_r_n_o. Calling sysconf() with _SC_THREAD_KEYS_MAX, _SC_THREAD_THREADS_MAX, or _SC_THREAD_DESTRUCTOR_ITERATIONS returns -1 without setting errno, because no maximum limit can be determined. The system supports at least the minimum values defined by _POSIX_THREAD_KEYS_MAX, _POSIX_THREAD_THREADS_MAX, and _POSIX_THREAD_DESTRUCTOR_ITERATIONS and can support higher values depending upon system resources. The following SPARC and x86 platform variables return EIN- VAL: _SC_COHER_BLKSZ _SC_DCACHE_ASSOC _SC_DCACHE_BLKSZ _SC_DCACHE_LINESZ _SC_DCACHE_SZ _SC_DCACHE_TBLKSZ _SC_ICACHE_ASSOC _SC_ICACHE_BLKSZ _SC_ICACHE_LINESZ _SC_ICACHE_SZ _SC_SPLIT_CACHE ERRORS The sysconf() function will fail if: EINVAL The value of the _n_a_m_e argument is invalid. ATTRIBUTES See attributes(5) for descriptions of the following attri- butes: ____________________________________________________________ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | |______________________________|______________________________| | Architecture | SPARC and x86 | |______________________________|______________________________| | MT-Level | MT-Safe, Async-Signal-Safe | |______________________________|______________________________| SEE ALSO fpathconf(2), seteuid(2), setrlimit(2), attributes(5), stan- dards(5) SunOS 5.7 Last change: 10 Mar 1998 8 C Library Functions sysconf(3C) NOTES A call to setrlimit() may cause the value of OPEN_MAX to change. Multiplying sysconf(_SC_PHYS_PAGES) or sysconf(_SC_AVPHYS_PAGES) by sysconf(_SC_PAGESIZE) to deter- mine memory amount in bytes can exceed the maximum values representable in a long or unsigned long. The value of CLK_TCK may be variable and it should not be assumed that CLK_TCK is a compile-time constant. The _SC_PHYS_PAGES and _SC_AVPHYS_PAGES variables are specific to Solaris 2.3 or compatible releases. The _SC_THREAD_PRIO_INHERIT and _SC_THREAD_PRIO_PROTECT variables are currently not supported. A call to sysconf() with these variables as arguments returns -1. SunOS 5.7 Last change: 10 Mar 1998 9