Checking file exist in raspberry pi 2 using C language - c

Question

I am new to C language and learning it by experimenting.
My challenge: I am trying to verify if a file "Command.txt" exist in a folder in raspberry pi and then I have to read the content of the file.
My Code:
#include <sys/stat.h>
#include <unistd.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <wiringPi.h>
// Pin number declarations. We're using the Broadcom chip pin numbers.
const int pwmPin = 18; // PWM LED - Broadcom pin 18, P1 pin 12
const int ledPin = 23; // Regular LED - Broadcom pin 23, P1 pin 16
const int butPin = 17; // Active-low button - Broadcom pin 17, P1 pin 11
const int pwmValue = 75; // Use this to set an LED brightness
int file_exist(char *filename)
{
struct stat buffer;
return (stat(filename, &buffer) == 0);
}
int main(void)
{
// Setup stuff:
wiringPiSetupGpio(); // Initialize wiringPi -- using Broadcom pin numbers
pinMode(pwmPin, PWM_OUTPUT); // Set PWM LED as PWM output
pinMode(ledPin, OUTPUT); // Set regular LED as output
pinMode(butPin, INPUT); // Set button as INPUT
pullUpDnControl(butPin, PUD_UP); // Enable pull-up resistor on button
printf("Blinker is running! Press CTRL+C to quit.\n");
while(1)
{
FILE *command_file;
char command[255];
while(file_exist("/home/pi/FTP/command.txt"))
{
command_file = fopen("/home/pi/FTP/command.txt", "r");
fgets(command, 255, (FILE*)command_file);
printf("1: %s\n", command );
if(command == "First Light ON")
{
digitalWrite(ledPin, HIGH); //Change the raspberryPi pin state to 1
}
else if(command == "First Light OFF")
{
digitalWrite(ledPin, LOW); //Change the raspberryPi pin state to 0
}
else
{
printf("Command is not yet defined");
}
fclose(command_file);
}
while(!(file_exist("/home/pi/FTP/command.txt")))
{
printf("File does not exist\n");
delay(1000); // Wait 1s again
}
}
return 0;
}
When I run this code using the gcc command in my raspberry pi, The program is executed but I only see "File does not exist" message even if the file exist in the given folder.
Please help me with the logic on this program.