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c - how to use correctly fork() and exec()

I have this code;

pid_t process;
process = fork();

if (process < 0){
   //fork error
   perror("fork");
   exit(EXIT_FAILURE);
}
if (process == 0){
   //i try here the execl
   execl ("process.c", "process" , n, NULL);
}
else {
   wait(NULL);
}

I don't know if this use of fork() and exec() combined is correct. When I try to run the program from the bash I do not receive any result, so I thought it could be a problem in this part of code.
Thanks.

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1 Answer

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by (71.8m points)

One problem is that

if (process = 0){

should read

if (process == 0){

Otherwise you're assigning zero to process and only calling execl if result is non-zero (i.e. never).

Also, you're trying to exec something called process.c. There's no doubt that one could have an executable called process.c. However, conventionally names ending in .c are given to C source code files. If process.c is indeed a C file, you need to compile and link it first.

Once you've built the executable, you need to either place it somewhere on $PATH or specify its full path to execle(). In many Unix environments placing it in the current directory won't be enough.

Finally, it's unclear what n is in the execle() call, but the name hints at a numeric variable. You need to make sure that it's a string and not, for example, an integer.


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