This Linux project creates a simple utility written in C that retrieves and displays system-level information, including the system name, memory usage, and processor details. It serves as an educational tool for understanding how to interact with Linux system calls and files like /proc/cpuinfo. The utility demonstrates the use of system calls such as uname, sysinfo, and gethostname, along with reading system data from Linux-specific files. It is ideal for beginners learning Linux system programming and provides a foundation for extending functionality, such as adding network statistics or disk usage information. Each component of the utility highlights a different aspect of Linux APIs, from retrieving kernel and architecture details with uname to gathering memory and uptime statistics using sysinfo, and processor details via /proc/cpuinfo.
Here's the code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/utsname.h>
#include <unistd.h>
#include <sys/sysinfo.h>
int main() {
struct utsname sys_info;
struct sysinfo mem_info;
char hostname[256];
// Get system name, release, version, and architecture
if (uname(&sys_info) == 0) {
printf("System Information:\n");
printf(" System Name: %s\n", sys_info.sysname);
printf(" Node Name: %s\n", sys_info.nodename);
printf(" Release: %s\n", sys_info.release);
printf(" Version: %s\n", sys_info.version);
printf(" Machine: %s\n", sys_info.machine);
} else {
perror("uname");
}
// Get hostname
if (gethostname(hostname, sizeof(hostname)) == 0) {
printf(" Hostname: %s\n", hostname);
} else {
perror("gethostname");
}
// Get uptime and memory information
if (sysinfo(&mem_info) == 0) {
printf("Memory and Uptime Information:\n");
printf(" Uptime: %ld seconds\n", mem_info.uptime);
printf(" Total RAM: %ld MB\n", mem_info.totalram / 1024 / 1024);
printf(" Free RAM: %ld MB\n", mem_info.freeram / 1024 / 1024);
printf(" Shared RAM: %ld MB\n", mem_info.sharedram / 1024 / 1024);
printf(" Buffered RAM: %ld MB\n", mem_info.bufferram / 1024 / 1024);
printf(" Total Swap: %ld MB\n", mem_info.totalswap / 1024 / 1024);
printf(" Free Swap: %ld MB\n", mem_info.freeswap / 1024 / 1024);
printf(" Process Count: %d\n", mem_info.procs);
} else {
perror("sysinfo");
}
// Get processor type
FILE *cpu_info = fopen("/proc/cpuinfo", "r");
if (cpu_info) {
char line[256];
printf("Processor Information:\n");
while (fgets(line, sizeof(line), cpu_info)) {
if (strncmp(line, "model name", 10) == 0) {
printf(" %s", line + 13); // Skip "model name : "
break;
}
}
fclose(cpu_info);
} else {
perror("/proc/cpuinfo");
}
return 0;
}
Copy the code and save as a .c file
For ex: sys_info.c
Compile and Run:
gcc sys_info.c -o sys_info
./sysinfo
end
There are some 36 million lines of C code in the Linux kernel. Learning a bit of C allows you to take a look 'under the hood' at some of the low-level elements and processes of the Linux operating system.
Stay tuned for more articles on learning the Linux OS. Next up is a 'mini-shell' written in C - a simplified version of the Bash shell that is educational and fun to play around with.
Ben Santora - December 2024
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