C program to check total and free RAM memory in Linux

Following C program helps you to identify what is the total and free memory / RAM available in your Linux machine.

$ vim checkfreemem.c

#include <stdio.h>
#include <sys/sysinfo.h>

void printmemsize(char *str, unsigned long ramsize) {
        printf("%s: %ld in bytes / %ld in KB / %ld in MB / %ld in GB\n",str, ramsize, ramsize/1024, (ramsize/1024)/1024, ((ramsize/1024)/1024)/1024);
}

int main(int argc, char **argv) {
        struct sysinfo info;
        sysinfo(&info);
        printf("uptime: %ld\n", info.uptime);
        // print total ram size
        printmemsize("totalram", info.totalram);
        printmemsize("freeram", info.freeram);
        printmemsize("sharedram", info.sharedram);
        printmemsize("bufferram", info.bufferram);
        printmemsize("freeswap", info.freeswap);
        printf("current running processes: %d\n", info.procs);
        return 0;
}

$ gcc -o checkfreemem checkfreemem.c

$ ./checkfreemem
uptime: 53186
totalram: 8206098432 in bytes / 8013768 in KB / 7825 in MB / 7 in GB
freeram: 225759232 in bytes / 220468 in KB / 215 in MB / 0 in GB
sharedram: 639688704 in bytes / 624696 in KB / 610 in MB / 0 in GB
bufferram: 3016544256 in bytes / 2945844 in KB / 2876 in MB / 2 in GB
freeswap: 2036477952 in bytes / 1988748 in KB / 1942 in MB / 1 in GB
current running processes: 824

As you can see, our program displays total RAM, Free RAM and other details.

This you can corelate with Linux “free” command as,

$ free
              total        used        free      shared  buff/cache   available
Mem:        8013768     1481188      891768      545628     5640812     5647400
Swap:       2097148      128368     1968780

We can check this numbers in more easier way as,

$ free -h
              total        used        free      shared  buff/cache   available
Mem:           7.6G        1.4G        898M        507M        5.4G        5.4G
Swap:          2.0G        125M        1.9G