/* systeminfo.c */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/utsname.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <linux/kernel.h>

int main(int argc,char *argv[])
{
    struct utsname uts;
    char cwd[120];
    char *env;
    struct rlimit rlim;
    struct sysinfo s_info;

    if(uname(&uts) >= 0){
        printf("                   System name: %s\n",
                uts.sysname);
        printf("                       Release: %s\n",
                uts.release);
        printf("                       Version: %s\n",
                uts.version);
        printf("                      Hardware: %s\n",
                uts.machine);
        printf("                     Node name: %s\n",
                uts.nodename);
#ifdef USE_GNU
        printf("                   Domain name: %s\n",
                uts.domainname);
#else
        printf("                   Domain name: %s\n",
                uts.__domainname);
#endif
    }

    if(getcwd(cwd,sizeof(cwd)))
        printf("             Current directory: %s\n",
            cwd);

    if((env = getenv("SHELL")) != NULL)
        printf("    Environment variable SHELL: %s\n",
            env);
    printf("                       User ID: %d\n",
            getuid());
    printf("                      Group ID: %d\n",
            getgid());
    printf("                    Process ID: %d\n",
            getpid());
    printf("             Parent process ID: %d\n",
            getppid());
    printf("                         Login: %s\n",
            getlogin());
    printf("                    User shell: %s\n",
            getusershell());
    printf(" Maximum arg length for exec(): %ld\n",
            sysconf(_SC_ARG_MAX));
    printf("    Maximum processes per user: %ld\n",
            sysconf(_SC_CHILD_MAX));
    printf("        Clock ticks per second: %ld\n",
            sysconf(_SC_CLK_TCK));
    printf("   Maximum streams per process: %ld\n",
            sysconf(_SC_STREAM_MAX));
    printf("Maximum open files per process: %ld\n",
            sysconf(_SC_OPEN_MAX));
    printf("Maximum chars in timezone name: %ld\n",
            sysconf(_SC_TZNAME_MAX));
    printf("   Maximum command line length: %ld\n",
            sysconf(_SC_LINE_MAX));
    printf("   POSIX job control supported: %s\n",
            sysconf(_SC_CHILD_MAX) ? "true" : "false");
    printf("   POSIX.1 compliance (YYYYMM): %ld\n",
            sysconf(_SC_VERSION));
    printf("   POSIX.2 compliance (YYYYMM): %ld\n",
            sysconf(_SC_2_VERSION));
    printf("    POSIX.2 locale by localdef: %s\n",
            sysconf(_SC_2_LOCALEDEF) ? "true" : "false");
    printf("  POSIX.2 software development: %s\n",
            sysconf(_SC_2_SW_DEV) ? "true" : "false");

    sysinfo(&s_info);
    printf("             Uptime in seconds: %d\n",
            s_info.uptime);
    printf("        Load for past 1 minute: %d\n",
            s_info.loads[0]);
    printf("       Load for past 5 minutes: %d\n",
            s_info.loads[1]);
    printf("      Load for past 15 minutes: %d\n",
            s_info.loads[2]);
    printf("           Total amount of RAM: %d\n",
            s_info.totalram);
    printf("            Amount of free RAM: %d\n",
            s_info.freeram);
    printf("          Amount of shared RAM: %d\n",
            s_info.sharedram);
    printf("      Amount of RAM in buffers: %d\n",
            s_info.bufferram);
    printf("              Total swap space: %d\n",
            s_info.totalswap);
    printf("               Free swap space: %d\n",
            s_info.freeswap);
    printf("     Total number of processes: %d\n",
            s_info.procs);

    exit(0);
}