system() does not work - c

Question

My program reads and stores standard input into a char array cmd and then call system(cmd). I printed out cmd and its content is what I expected. But system(cmd) does not save the content in report.log. I tried with a literal string stored in cmd2, and this time it worked. So what is wrong with system(cmd)?
And I am using Windows 8.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>
#include <time.h>
#define MAXLEN 100
char *now(){
time_t t;
time(&t);
return asctime(localtime(&t));
}
int main(int argc, char *argv[])
{
char comment[80];
char cmd[120];
fgets(comment, 80, stdin);
sprintf(cmd, "echo '%s %s' >> report.log", comment, now());
printf("%s", cmd); // content of cmd is what I expect
system(cmd); // does not work, why?
char cmd2 = "echo 'Hello world' >> report.log";
system(cmd2); // work
return 0;
}

Answer 1

Your problem maybe with the excess \ns present in your inputs to sprintf().
fgets() scans and stores the \n from the stdin. You need to get rid of that \n and replace that with a null.
asctime() returns a ctime() return style string, again ended with a newline \n. You need to remove (replace) that too.
You can check the following code for your reference.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdarg.h>
#include <time.h>
#define MAXLEN 100
char *now(){
time_t t;
time(&t);
return asctime(localtime(&t));
}
int main(int argc, char *argv[])
{
char comment[80] = {0};
char cmd[120] = {0};
char * timestring = NULL; //initialize local variables, good practice
fgets(comment, 80, stdin);
comment[ strlen(comment) -1] = 0; //reomve the trailing \n taken by fgtes(), replace by null
timestring = now();
timestring[strlen(timestring)-1] = 0; //remove the \n from ctime() return style string, replace b null
sprintf(cmd, "echo '%s %s' >> report.log", comment, timestring);
printf(">> The string is : %s\n", cmd);
system(cmd); // should work now.. :-)
return 0;
}