我需要调用什么API才能使系统正常运行? [英] What API do I call to get the system uptime?

问题描述

我想从基于linux的系统上运行的C应用程序中获取系统正常运行时间.我不想调用uptime(1)并解析输出，我想调用我怀疑存在的基础C API.任何人都知道是否有这样的电话，或者uptime(1)只是处理从wtmp获得的记录吗?

I would like to get the system uptime from within a C application running on a linux-based system. I don't want to call uptime(1) and parse the output, I'd like to call the underlying C API I suspect exists. Anyone know if there is such a call, or does uptime(1) simply process records obtained from wtmp?

推荐答案

您要查找的系统调用是sysinfo().

The system call you're looking for is sysinfo().

它在sys/sysinfo.h中定义

It's defined in sys/sysinfo.h

它的签名是: int sysinfo(struct sysinfo * info)

Its signature is: int sysinfo(struct sysinfo *info)

从内核2.4开始，结构看起来像这样:

Since kernel 2.4, the structure has looked like this:

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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