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SYSCONF(3) FreeBSD Library Functions Manual SYSCONF(3) NAME sysconf -- get configurable system variables SYNOPSIS #include <unistd.h> long sysconf(int name); DESCRIPTION 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 con- stants 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 arguments to execve(2) (including the envi- ronment). _SC_CHILD_MAX The maximum number of simultaneous processes per user ID. _SC_CLK_TCK The number of clock ticks per second. _SC_NGROUPS_MAX The maximum number of supplemental groups. _SC_OPEN_MAX The maximum number of open files per user ID. _SC_STREAM_MAX The minimum maximum number of streams that a process may have open at any one time. _SC_TZNAME_MAX The minimum maximum number of types supported for the name of a time zone. _SC_JOB_CONTROL Returns 1 if job control is available on this system, otherwise -1. _SC_SAVED_IDS Returns 1 if saved set-group-ID and saved set-user-ID is avail- able, otherwise -1. _SC_VERSION The version of ISO/IEC 9945 (POSIX 1003.1) with which the system attempts to comply. _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 parentheses 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 expres- sion 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 sup- port the C-Language Bindings Option, otherwise -1. _SC_2_C_DEV Return 1 if the system supports the C-Language Development Utili- ties Option, otherwise -1. _SC_2_CHAR_TERM Return 1 if the system supports at least one terminal type capa- ble 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 Op- tion, otherwise -1. _SC_2_LOCALEDEF Return 1 if the system supports the creation of locales, other- wise -1. _SC_2_SW_DEV Return 1 if the system supports the Software Development Utili- ties Option, otherwise -1. _SC_2_UPE Return 1 if the system supports the User Portability Utilities Option, otherwise -1. _SC_PAGESIZE The size of a system page in bytes. _SC_FSYNC Return 1 if the system supports the File Synchronisation Option, otherwise -1. _SC_XOPEN_SHM Return 1 if the system supports the Shared Memory Option, other- wise -1. _SC_SEM_NSEMS_MAX The maximum number of semaphores in the system or -1 if the sys- tem does not support the Semaphores Option. _SC_SEM_VALUE_MAX The maximum value a semaphore may have or -1 if the system does not support the Semaphores Option. _SC_PHYS_PAGES The number of pages of physical memory. _SC_AVPHYS_PAGES The number of pages of physical memory not currently in use by the system. _SC_GETGR_R_SIZE_MAX The maximum size of the data buffer for the getgrgid_r() and getgrnam_r() functions. _SC_GETPW_R_SIZE_MAX The maximum size of the data buffer for the getpwuid_r() and getpwnam_r() functions. _SC_LOGIN_NAME_MAX The maximum length of a login name. _SC_THREAD_SAFE_FUNCTIONS The level of support for thread-safe (re-entrant) functions. _SC_NPROCESSORS_CONF The number of processors configured. _SC_NPROCESSORS_ONLN The number of processors online (capable of running processes). _SC_HOST_NAME_MAX The maximum size of a hostname, not counting NULL. _SC_MONOTONIC_CLOCK Return the POSIX version of the implementation of the Monotonic Clock option that this system conforms to, or -1 if unavailable. 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 func- tionality that is not supported, -1 is returned and errno is not modi- fied. Otherwise, the current variable value is returned. ERRORS The sysconf() function may fail and set errno for any of the errors spec- ified for the library function sysctl(2). In addition, the following er- ror may be reported: [EINVAL] The value of the name argument is invalid. SEE ALSO pathconf(2), sysctl(2) STANDARDS The sysconf() function conforms to IEEE Std 1003.1-1988 ("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. FreeBSD 13.0 August 11, 2019 FreeBSD 13.0
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | BUGS
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