使用fork和exec在C linux中执行程序

Question

I want to execute a C program in Linux using fork and exec system calls. I have written a program msg.c and it's working fine. Then I wrote a program msg1.c .

When I do ./a.out msg.c , it's just printing msg.c as output but not executing my program.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h> /* for fork */
#include <sys/types.h> /* for pid_t */
#include <sys/wait.h> /* for wait */

int main(int argc,char** argv)
{
/*Spawn a child to run the program.*/
    pid_t pid=fork();
    if (pid==0)
    { /* child process */
    //      static char *argv[]={"echo","Foo is my name.",NULL};
            execv("/bin/echo",argv);
            exit(127); /* only if execv fails */
    }
    else
    { /* pid!=0; parent process */
           waitpid(pid,0,0); /* wait for child to exit */
    }
 return 0;
}

Answer 1

argv[0] contains your program's name and you are Echo'ing it. Works flawlessly ;-)

Answer 2

/ bin / echo msg.c将打印msg.c作为输出，如果您需要执行msg二进制文件，则需要将代码更改为execv（“ path / msg”）;

Answer 3

your exec executes the program echo which prints out whatever argv's value is;
furthermore you cannot "execute" msg.c if it is a sourcefile, you have to compile ( gcc msg.c -o msg ) it first, and then call something like exec("msg")

Answer 4

C programs are not executables (unless you use an uncommon C interpreter).

You need to compile them first with a compiler like GCC , so compile your msg.c source file into a msg-prog executable (using -Wall to get all warnings and -g to get debugging info from the gcc compiler) with:

gcc -Wall -g msg.c -o msg-prog

^{Take care to improve the msg.c till you get no warnings.}

Then, you might want to replace your execv in your source code with something more sensible. Read execve(2) and execl(3) and perror(3) . Consider using

execl ("./msg-prog", "msg-prog", "Foo is my name", NULL);
perror ("execl failed");
exit (127);

Read Advanced Linux Programming .

NB: You might name your executable just msg instead of msg-prog ....