进程nice值

[e-mail]:~/test/process>more  setpriority.c
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/resource.h>
int print_getpriority(int which,int who)
{
    int prio;

    errno = 0;
    prio = getpriority(which,who);
    if(prio == -1 && errno != 0) {
        printf("getpriority error\n");
        return -1;
    }
    return prio;
    //printf("nice value = %d\n", prio);
}

int main(int argc, char* argv[])
{
    int which,prio;
    id_t who;

    if (argc != 4 || strchr("pgu", argv[1][0]) == NULL) {
        printf("%s {p|g|u} who priority\n"
                " set priority of: p=process;g=process group;"
                "u=process for user\n",argv[0]);
        return 0;
    }
    printf("prio=%d\n",print_getpriority(PRIO_PROCESS,0));
    which = (argv[1][0] == 'p') ? PRIO_PROCESS :(argv[1][0] == 'g') ? PRIO_PGRP:PRIO_USER;
    who = atoi(argv[2]);
    prio = atoi(argv[3]);

    if(setpriority(which,who,prio) == -1) {
        printf("setpriority error\n");
        return -1;
    }

    printf("priority=%d\n",print_getpriority(which,who));

    exit(0);
}

编译运行：

[e-mail]:~/test/process>gcc -g setpriority.c -o setpriority
[e-mail]:~/test/process>./setpriority p 0 5
prio=0-------------------------默认进程的nice值为0
priority=5 --------非特权进程可以修改自己或者是有效用户ID与目的进程的有效用户ID或者真实用户ID一致的目的进程的nice值