wait child process to receive signal

main.c

/**
  Author: Dmitry Afanasyev
  Compiler version: 
  gcc --version
  gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
  Compile: 
  gcc main.c -o test && ./test
  
  PHP version:
    php --version
    PHP 7.4.3 (cli) 
    
  Full test suite: 

    $ cat actual-work.php 
    <?php

    pcntl_alarm(5);
    echo "alarm() call executed\n";

    for ($i = 0; $i < 10; $i++) {
        echo "doing actual work in php script\n";
        sleep(1);
    }
    
    $ gcc main.c -o test
    $ ./test > log.txt
    $ cat log.txt
    alarm() call executed
    doing actual work in php script
    doing actual work in php script
    doing actual work in php script
    doing actual work in php script
    doing actual work in php script
    WATCHDOG DEBUG parent waits child to change it's status...
    WATCHDOG ERROR child exited by receiving signal: 14
 */
#include <sys/wait.h> // wait
#include <unistd.h> // alarm
#include <stdio.h> // printf

int main()
{
    pid_t child;
    int status;
    child = fork();
    if (child < 0)
    {
        // error, no child process created, 
        printf("WATCHDOG ERROR failed to create child process, exiting...\n");
        return -1;
    } else if  (child == 0)
    {
        // I'm the child now

        // NOTE: if you want to add arguments to script, just add them to array, e.g.: {"/foo/bar/baz" , "-foo" , "-bar" , NULL};
        // ALSO NOTE: all paths MUST be absolute, obviously, on your system paths would be different
        const char *arguments[64] = {"/usr/bin/php", "/home/dmitry/fun/ar-help/actual-work.php", NULL}; 
        
        printf("WATCHDOG DEBUG calling php script...\n");

        // system() call is considered problematic, exec* family is better
        if (-1 == execve(arguments[0], (char **) arguments, NULL))
        {
            printf("WATCHDOG ERROR execve() script failed, exiting...");
            return -1;
        }

    } else
    {
        // I'm the parent now
        printf("WATCHDOG DEBUG parent waits child to change it's status...\n");
        wait(&status);
        if (WIFEXITED(status))
        {
            // child exited normally, calling exit(3)
            printf("WATCHDOG INFO child finished normally\n");
        } else if (WIFSIGNALED(status))
        {
            // child exited by receiving signal 
            int signal_id = WTERMSIG(status);
            printf("WATCHDOG ERROR child exited by receiving signal: %d\n", signal_id);
        }
        return 0;
    }
}