The sched_getscheduler() function returns
the scheduling policy of the process specified by pid. If the value of pid is negative, the behavior of the sched_getscheduler() function is unspecified.
The values that can be returned by sched_getscheduler() are defined in the header <sched.h> and described on the sched_setscheduler(3RT) manual page.
If a process specified by pid exists and if the calling process has permission, the scheduling policy will be returned for the process whose process ID is equal to pid.
If pid is 0, the scheduling policy will be returned for the calling process.