CODEWITHSUNDEEP
cprocessexec
joseph cornell
joseph cornell

Reputation: 71

how to use exec() to run a c program from another c program

i've been trying to use execvp to run a c program but it always seems to fail.

from main.c

int main() {
char* args[] = {"2", "1"};
    if(execvp("trial.c", args) == -1) {
        printf("\nfailed connection\n");
    }

from trial.c

int main(int argc, char** argv){
printf("working");
return 1;
}

I think i tried every way to possibly represent that file location in the exec() and it always results in "failed connection".

Upvotes: 4

Views: 9689

Answers (4)

Geezer
Geezer

Reputation: 5710

If you're trying to call execvp() on a source file then this is not what this function does. The first argument is expected to be a path of an executable. If you want to run the program which trial.c is the source of, you should build (compile and such) it first. For example like this:

$ gcc -o trial trial.c

Then call execvp() on the your newly created executable instead of the source file:

if(execvp("trial", args) == -1) { //...

Upvotes: 0

kiran Biradar
kiran Biradar

Reputation: 12732

First argument for execvp is path to executable. You need to build the executable for trial.c and pass the path of the executable to execvp.

if(execvp("---path to executable---/ExecTrial", args) == -1) {
    printf("\nfailed connection\n");
}

If you don't pass the executable path, execvp will search the executable in the colon-separated list of directory pathnames specified in the PATH environment variable.

Upvotes: 1

dbush
dbush

Reputation: 223699

The first parameter to execvp expects the name of an executable file. What you've passed it is the name of a source file. You need to first compile trial.c, then pass the name of the compiled executable to execvp.

Regarding the second parameter to execvp, the last element in the array must be NULL. That's how it knows it reached the end of the list. Also, by convention the first parameter to a program is the name of the program itself.

So first compile trial.c:

gcc -g -Wall -Wextra -o trial trial.c

Then modify how to call it in main.c:

int main() {
    char* args[] = { "trial", "2", "1", NULL };
    if(execvp("trial", args) == -1) {
        printf("\nfailed connection\n");
    return 1;
}

Upvotes: 2

Clifford
Clifford

Reputation: 93466

trial.c is not a valid executable file. C is not a scripting or interpreted language; you cannot run C source files directly. A C program must be compiled and linked into an executable.

Upvotes: 0

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