我想从一个基于Linux的系统上运行的C应用程序中得到系统的正常运行时间。 我不想调用运行时间（1），并解析输出，我想调用底层的C API我怀疑存在。 任何人都知道，如果有这样的称呼，还是从wtmp中获得的正常运行时间（1）简单的过程记录？
Answer 1:
系统调用你要找的是SYSINFO（）。
它在sys / sysinfo.h定义
它的签名是：INT SYSINFO（结构SYSINFO *信息）
由于2.4内核，该结构是这样的：
struct sysinfo {
long uptime; /* Seconds since boot */
unsigned long loads[3]; /* 1, 5, and 15 minute load averages */
unsigned long totalram; /* Total usable main memory size */
unsigned long freeram; /* Available memory size */
unsigned long sharedram; /* Amount of shared memory */
unsigned long bufferram; /* Memory used by buffers */
unsigned long totalswap; /* Total swap space size */
unsigned long freeswap; /* swap space still available */
unsigned short procs; /* Number of current processes */
unsigned long totalhigh; /* Total high memory size */
unsigned long freehigh; /* Available high memory size */
unsigned int mem_unit; /* Memory unit size in bytes */
char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding for libc5 */
};
玩得开心！
Answer 2:
这将是这样的。
#include <stdio.h>
#include <errno.h>
#include <linux/unistd.h> /* for _syscallX macros/related stuff */
#include <linux/kernel.h> /* for struct sysinfo */
#include <sys/sysinfo.h>
long get_uptime()
{
struct sysinfo s_info;
int error = sysinfo(&s_info);
if(error != 0)
{
printf("code error = %d\n", error);
}
return s_info.uptime;
}
见“人SYSINFO”获取更多信息。
Answer 3:
阅读文件/proc/uptime和采取的第一个十进制数为以秒为单位的正常运行时间。
从man 5 proc ：
/proc/uptime
This file contains two numbers: the uptime of the system (sec‐
onds), and the amount of time spent in idle process (seconds).
Answer 4:
还有clock_gettime （可能需要-lrt ）。 我见过的行为（我不会声称它保证），但鉴于CLOCK_MONOTONIC作为clk_id是返回给定的系统正常运行时间struct timespec *参数。
#include <stdio.h>
#include <time.h>
int main(int argc, char* argv[]) {
struct timespec t;
clock_gettime(CLOCK_MONOTONIC, &t);
printf("tv_sec=%llu tv_nsec=%llu\n",
(unsigned long long)t.tv_sec,
(unsigned long long)t.tv_nsec);
return 0;
}
Answer 5:
#include <sys/sysinfo.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <grp.h>
int main() {
struct sysinfo sys_info;
struct group* grp;
gid_t gid;
char** users;
int days, hours, mins, x = 1;
system("clear");
printf("\033[4;40m Systems information \033[0;m \n");
if(sysinfo(&sys_info) != 0)
perror("sysinfo");
days = sys_info.uptime / 86400;
hours = (sys_info.uptime / 3600) - (days * 24);
mins = (sys_info.uptime / 60) - (days * 1440) - (hours * 60);
printf("\033[1;33m Uptime: \033[0;36m %ddays, %dhours, %dminutes, %ldseconds \033[0;m \n",
days, hours, mins, sys_info.uptime % 60);
printf("\033[1;33m Load Avgs: \033[0;m 1min(%ld) 5min(%ld) 15min(%ld) \n",
sys_info.loads[0], sys_info.loads[1], sys_info.loads[2]);
printf("\033[1;33m Total Ram: \033[0;m %ldk \t Free: %ldk \n", sys_info.totalram / 1024, sys_info.freeram / 1024);
printf(" \033[1;33m Shared Ram: \033[0;m %ldk ", sys_info.sharedram / 1024);
printf(" Buffered Ram: %ldk \n", sys_info.bufferram / 1024);
printf("\033[1;33m Total Swap: \033[0;m %ldk \t Free swap: %ldk \n", sys_info.totalswap / 1024, sys_info.freeswap / 1024);
printf("\033[1;33m Total High Memory: \033[0;m %ldk Free high memory: %ldk \033[0;m \n", sys_info.totalhigh / 1024, sys_info.freehigh / 1024);
printf(" \n");
printf("\033[1;44m Total Number of processes: %d \033[0;m \n", sys_info.procs);
gid = getgid();
printf(" Group ID: \033[031m %d", gid);
if((grp = getgrgid(gid)) == NULL ) return 1;
printf("\033[0;m Group %s ", grp->gr_name );
printf("\n Users in your group ");
for( users = grp->gr_mem; *users != NULL; users++,++x ); printf( "%d", ++x);
if(strcmp(grp->gr_passwd,"x") == 0) printf(" Password is protected by shadow file. \n");
else printf("Password: %s ", grp->gr_passwd);
return 0;
}
文章来源: What API do I call to get the system uptime?
