time.c

在linux9中实现统计运行时间的功能

#include <stdio.h>
#include <sys/types.h>
#include <sys/times.h>
#include <unistd.h>

static void pr_times(clock_t, struct tms *,struct tms *);
static void do_cmd(char *);

int main(int argc,char *argv[])
{
    int i;
     
    setbuf(stdout,NULL);
    if(argc < 2)
    {
       printf("-wsh: syntax error near unexpected token 'newline'\n");
       exit(0);
    }
    for(i = 1;i < argc;i++)
        do_cmd(argv[i]);
    exit(0);
}

static void do_cmd(char *cmd)
{
    struct tms  tmsstart,tmsend;
    clock_t     start,end;
    int         status;
    
    if((start = times(&tmsstart)) == -1)
        perror("times error");
    if((status = system(cmd)) < 0)
        perror("system() error");
    if((end = times(&tmsend)) == -1)
        perror("times error");
    
    pr_times(end-start,&tmsstart,&tmsend);
    exit(status);
}

static void pr_times(clock_t real,struct tms *tmsstart,struct tms *tmsend)
{
    static long     clktck = 0;
    
    if(clktck == 0)
        if((clktck = sysconf(_SC_CLK_TCK)) < 0)
            perror("sysconf error");
    printf("\n");
    printf("real%8.3f\n",real/(double)clktck);
    printf("user%8.3f\n",
      (tmsend->tms_utime - tmsstart->tms_utime)/(double)clktck);
    printf("sys %8.3f\n",
      (tmsend->tms_stime - tmsstart->tms_stime)/(double)clktck);
}