| _SC_ARG_MAX |
| | The maximum bytes of argument to execve(2). |
| _SC_CHILD_MAX |
| | The maximum number of simultaneous processes per user id. |
| _SC_CLK_TCK |
| | The frequency of the statistics clock in ticks per second. |
| _SC_IOV_MAX |
| | The maximum number of elements in the I/O vector used by readv(2), writev(2), recvmsg(2), and sendmsg(2). |
| _SC_NGROUPS_MAX |
| | The maximum number of supplemental groups. |
| _SC_NPROCESSORS_CONF |
| | The number of processors configured. |
| _SC_NPROCESSORS_ONLN |
| | The number of processors currently online. |
| _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 timezone. |
| _SC_JOB_CONTROL |
| | Return 1 if job control is available on this system, otherwise -1. |
| _SC_SAVED_IDS |
| | Returns 1 if saved set-group and saved set-user ID is available, otherwise -1. |
| _SC_VERSION |
| | The version of -p1003.1 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 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 -p1003.2 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, otherwise -1. |
| _SC_2_CHAR_TERM |
| | Return 1 if the system supports at least one terminal type capable of all operations described in -p1003.2, 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. |
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