This Process Monitor uses a C program designed to list all running processes on a Linux system. It displays the Process ID (PID), memory usage, and CPU usage for each process, updating this information every 5 seconds.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
void display_process_info(long pid, long uptime);
void list_processes(long uptime);
// Function to get system uptime
long get_system_uptime() {
FILE *file = fopen("/proc/uptime", "r");
if (!file) {
perror("fopen");
return -1;
}
long uptime;
fscanf(file, "%ld", &uptime);
fclose(file);
return uptime;
}
int main() {
while (1) {
long uptime = get_system_uptime();
if (uptime != -1) {
list_processes(uptime);
sleep(5); // Update every 5 seconds
}
}
return 0;
}
void list_processes(long uptime) {
DIR *dir;
struct dirent *entry;
dir = opendir("/proc");
if (dir == NULL) {
perror("opendir");
return;
}
printf("PID\tMemory (KB)\tCPU (%%)\n");
printf("------------------------------\n");
while ((entry = readdir(dir)) != NULL) {
if (entry->d_type == DT_DIR) {
char *endptr;
long pid = strtol(entry->d_name, &endptr, 10);
if (*endptr == '\0') {
// It's a valid PID
display_process_info(pid, uptime);
}
}
}
closedir(dir);
}
void display_process_info(long pid, long uptime) {
char path[256];
snprintf(path, sizeof(path), "/proc/%ld/stat", pid);
FILE *file = fopen(path, "r");
if (!file) {
perror("fopen");
return;
}
// Read the contents of /proc/[pid]/stat
char buffer[1024];
long utime, stime, starttime;
if (fgets(buffer, sizeof(buffer), file) != NULL) {
sscanf(buffer, "%*d %*s %*c %*d %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %*u %ld %ld %*d %*d %*d %*d %*u %*u %*d %*u %*d %*u %*u %*u %ld", &utime, &stime, &starttime);
}
fclose(file);
snprintf(path, sizeof(path), "/proc/%ld/statm", pid);
file = fopen(path, "r");
if (!file) {
perror("fopen");
return;
}
// Read memory usage from /proc/[pid]/statm
long mem_usage;
if (fscanf(file, "%ld", &mem_usage) == 1) {
mem_usage = mem_usage * getpagesize() / 1024; // Convert to KB
}
fclose(file);
// Calculate CPU usage
long total_time = utime + stime;
long seconds = uptime - (starttime / sysconf(_SC_CLK_TCK));
double cpu_usage = 100.0 * ((double) total_time / sysconf(_SC_CLK_TCK) / (double) seconds);
printf("%ld\t%ld\t\t%.2f\n", pid, mem_usage, cpu_usage);
}
Features
Lists all running processes.
Displays details such as PID, memory usage (in KB), and CPU usage (as a percentage).
Updates process information periodically to reflect real-time system activity.
Usage
Compilation
To compile the program, use the following command:
gcc process_monitor.c -o process_monitor
Execution
To run the program, execute:
sudo ./process_monitor
Example Output
The program outputs a list of running processes with their respective memory and CPU usage:
PID Memory (KB) CPU (%)
1 2616 0.00
5 2800 0.00
12 2624 0.00
...
How It Works
The program reads process information from the /proc directory.
It fetches memory usage data from /proc/[pid]/statm.
CPU usage is calculated based on the process's CPU time and the system uptime, read from /proc/[pid]/stat and /proc/uptime, respectively.
The information is updated every 5 seconds to provide a real-time view.
Considerations
Use on any PC running the Linux OS. Or use WSL with Windows. Note: Running the program in Windows Subsystem for Linux (WSL) should work similarly to a native Linux environment, though CPU usage will likely be very minimal if there are few active processes.
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