linux已开机时间 系统信息

linux 查看系统运行时间 （从开机当现在的开机时间）  

1.uptime命令
输出:16:11:40 up 59 days, 4:21, 2 users, load average: 0.00, 0.01, 0.00

2.查看/proc/uptime文件计算系统启动时间
cat /proc/uptime
输出: 5113396.94 575949.85
第一数字即是系统已运行的时间5113396.94 秒，运用系统工具date即可算出系统启动时间

代码: 
date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"

输出: 2008-11-09 11:50:31

3.查看/proc/uptime文件计算系统运行时间

代码:  
cat /proc/uptime| awk -F. '{run_days=$1 / 86400;run_hour=($1 % 86400)/3600;run_minute=($1 % 3600)/60;run_second=$1 % 60;printf("系统已运行：%d天%d时%d分%d秒",run_days,run_hour,run_minute,run_second)}'

输出:系统已运行：59天4时13分9秒

这样你就能轻松地应用Linux查看系统时间。

 

c代码：

 

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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 */ };

　　

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#include <stdio.h> #include <time.h> #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;     error = sysinfo(&s_info);     if(error != 0)     {         printf("code error = %d\n", error);     }     return s_info.uptime; }   long out_sys(){       /* Conversion constants. */       const long minute = 60;       const long hour = minute * 60;       const long day = hour * 24;       const double megabyte = 1024 * 1024;       /* Obtain system statistics. */       struct sysinfo si;       sysinfo (&si);       /* Summarize interesting values. */       printf ("system uptime : %ld days, %ld:%02ld:%02ld\n",               si.uptime / day, (si.uptime % day) / hour,               (si.uptime % hour) / minute, si.uptime % minute);       printf ("total RAM     : %5.1f MB\n", si.totalram / megabyte);       printf ("free RAM      : %5.1f MB\n", si.freeram / megabyte);       printf ("process count : %d\n", si.procs); }   int main(int argc, char* argv[]) {   struct timespec t;   clock_gettime(CLOCK_MONOTONIC, &t);   printf("tv_sec=%llu tv_nsec=%llu\n uptime time:%llu\n",     (unsigned long long)t.tv_sec,     (unsigned long long)t.tv_nsec,     get_uptime());     out_sys();   return 0; }