#### 31.4.1 Definition of `sysconf`

— Function: long int sysconf (int parameter)

> This function is used to inquire about runtime system parameters. The parameter argument should be one of the ‘`_SC_`’ symbols listed below.

> The normal return value from `sysconf` is the value you requested. A value of `-1` is returned both if the implementation does not impose a limit, and in case of an error.

> The following `errno` error conditions are defined for this function:

> `EINVAL`
>   The value of the parameter is invalid.