CODEWITHSUNDEEP
cstring
aquemini
aquemini

Reputation: 960

String Manipulation and System Call in C

I'm a C amateur, and I'm having trouble manipulating strings in C. The objective is to add the current pid to a base string, then call it with system(system_call). I have the following:

char system_call[100] = "top -p "
char pid_string[30];

//quite a bit of other code

int main(int argc, char *argv[])
{
    pid_t pid = getpid();
    sprintf(pid_string,"%d",pid);
    strcat(system_call,pid_string);

    printf(system_call); //prints what I expect; something like 'top -p 5580'
    system(system_call); //doesn't work
}

The system call simply gives sh: system: not found. I'm sure people good with C will know the problem instantly. I thought maybe the trailing 0 after strings in C had something to do with it, but I'm too terrible at C to recognize it or know what to do about it. I also tried system("%s",system_call) but system only takes one argument. Is there something wrong with my memory allocation? Any insight is appreciated.

Upvotes: 0

Views: 276

Answers (2)

Ole Dittmann
Ole Dittmann

Reputation: 1774

Cant see any problem with your string construction, maybe the problem is that "system" itself does not work for some reason on your system :-), or "top" is not acessible

Upvotes: 2

Fred
Fred

Reputation: 8602

The variable pid is not given a value before use in the sprintf.

Upvotes: 2

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