fread problems

[kirany82]

Hi all,

I am writign a program to get the process no(linux) into an integer. i am not able to get the process no into integer array...this is the program.

please help me.

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>

#define COMMAND "pgrep BTComm > xyz"

int main() {

FILE *f = fopen("xyz", "rw");
int ret = system(COMMAND);
if(ret == 0)
printf("Command execution successful\n");
else if(ret < 0)
printf("System() Error\n");
else
printf("ret is not valid \n");

fseek(f, 0, SEEK_END);
int size = ftell(f);
rewind(f);
unsigned int pid[10];
// char *pid = (char*)malloc(size+1);
int res = fread(pid, sizeof(unsigned int), 10, f);
if(res != size)
printf("fread error\n");

printf("Process ID is: %d\n", pid[0]);

int x = kill(7487, SIGKILL);
if(x)
printf("Failed to kill process\n");

fclose(f);
}

in the place of 7487 in int x = kill(7487, SIGKILL); i want to put the processid.
if i put the char* in fread, i get the processid written to the file but not witht he integer.

please help me.

Thanks,
Kiran

[gpraghuram]

Hi all,

I am writign a program to get the process no(linux) into an integer. i am not able to get the process no into integer array...this is the program.

please help me.

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>

#define COMMAND "pgrep BTComm > xyz"

int main() {

FILE *f = fopen("xyz", "rw");
int ret = system(COMMAND);
if(ret == 0)
printf("Command execution successful\n");
else if(ret < 0)
printf("System() Error\n");
else
printf("ret is not valid \n");

fseek(f, 0, SEEK_END);
int size = ftell(f);
rewind(f);
unsigned int pid[10];
// char *pid = (char*)malloc(size+1);
int res = fread(pid, sizeof(unsigned int), 10, f);
if(res != size)
printf("fread error\n");

printf("Process ID is: %d\n", pid[0]);

int x = kill(7487, SIGKILL);
if(x)
printf("Failed to kill process\n");

fclose(f);
}

in the place of 7487 in int x = kill(7487, SIGKILL); i want to put the processid.
if i put the char* in fread, i get the processid written to the file but not witht he integer.

please help me.

Thanks,
Kiran

There is a porblem in the code.
First u are opening the file and calling the system command which in-turn creates the file.
So the descriptor what you have used for opening wont have any information about the file contents.
So make this change

int main() {
//....your code
        FILE *f = NULL;
        int ret = system(COMMAND);
       if(ret == 0)
//....your code
       f = fopen("xyz", "rw");
       //You dont need to do these steps...
        //fseek(f, 0, SEEK_END);
        //int size = ftell(f);
        //rewind(f);
        //unsigned int pid[10];
//      char *pid = (char*)malloc(size+1);
         ///start reding the info from file
        int res = fread(pid, sizeof(unsigned int), 10, f);
 

Raghuram