| sys_exit | Terminate the process with the given exit code. |
| sys_abort | Terminate the process abnormally (raises SIGABRT / triggers abort handler). |
| sys_system | Run a shell command and return its exit status. NULL → check if shell available. |
| sys_atexit | Register a function to be called at normal process exit.
Returns 0 on success, non-zero if the registration limit is exceeded. |
| sys_getenv | Return the value of the environment variable named name,
or NULL if not set. The returned pointer is owned by the environment. |
| sys_rand | Return a pseudo-random integer in [0, RAND_MAX]. |
| sys_srand | Seed the PRNG. Use sys_time_now_ns() for a time-based seed. |
| sys_abs | Absolute value of a 32-bit signed integer. |
| sys_llabs | Absolute value of a 64-bit signed integer. |
| sys_atoi | Convert a decimal string to int. Stops at the first non-digit. |
| sys_atoll | Convert a decimal string to long long. |
| sys_atof | Convert a decimal/scientific string to double. |
| sys_strtoll | Strtoll with explicit base (0 = auto-detect 0x/0 prefix).
If end is non-null it is set to the first character not consumed. |
| sys_strtoull | Convert string to unsigned long long. |
| sys_strtod | Convert string to double. |
| sys_strtof | Convert string to float. |
| sys_qsort | Sorts items in place; cmp(a, b) returns <0 / 0 / >0. |
| sys_bsearch | Binary search of sorted items; the index of an element equal to key, or
null. |
| sys_cpu_time_ns | Return processor time consumed by the program in nanoseconds.
Same clock as time_cpu_ns() (time.h). Returns -1 on error. |
| sys_time_now_ns | Return wall-clock time in nanoseconds since the Unix epoch.
Same clock as time_wall_ns() (time.h). Returns -1 on error. |
| sys_monotonic_ns | Return a monotonic timestamp in nanoseconds (suitable for elapsed-time
measurement; epoch is unspecified). Returns -1 on error. |