Execing Processes in Cilk

Our example demonstrates how to replace the current process with another one using Cilk. This is similar to the classic exec function in Unix-like operating systems.

#include <cilk/cilk.h>
#include <cstdlib>
#include <iostream>
#include <unistd.h>

int main() {
    // For our example, we'll exec 'ls'. We need to provide the full path to the binary.
    const char* binary = "/bin/ls";

    // Arguments for the new process. The first argument should be the program name.
    char* const args[] = {(char*)"ls", (char*)"-a", (char*)"-l", (char*)"-h", NULL};

    // We'll use the current environment for the new process.
    extern char** environ;

    // Here's the actual exec call. If successful, the execution of our process will end
    // here and be replaced by the '/bin/ls -a -l -h' process.
    int result = execve(binary, args, environ);

    // If execve returns, it must have failed
    if (result == -1) {
        std::cerr << "execve failed: " << strerror(errno) << std::endl;
        return 1;
    }

    return 0;
}

When we run our program, it is replaced by ls:

$ g++ -fcilkplus exec_process.cpp -o exec_process
$ ./exec_process
total 20K
drwxr-xr-x  2 user user 4.0K Jun 15 10:00 .
drwxr-xr-x 10 user user 4.0K Jun 15 09:59 ..
-rwxr-xr-x  1 user user 8.7K Jun 15 10:00 exec_process
-rw-r--r--  1 user user  543 Jun 15 10:00 exec_process.cpp

Note that Cilk, being an extension of C++, doesn’t offer a direct equivalent to Go’s exec.LookPath. In this example, we’ve used the full path to the ls binary. In a more robust implementation, you might want to search for the binary in the system’s PATH.

Also, Cilk doesn’t have a direct equivalent to Go’s syscall.Exec. Instead, we’re using the POSIX execve function, which is available on Unix-like systems. This function replaces the current process image with a new process image.

Remember that Cilk is primarily used for parallel computing, and this example doesn’t showcase its parallel features. In a more typical Cilk program, you might use cilk_spawn and cilk_sync to create and manage parallel tasks.