Process Management in C

Description

This project contains a series of C programs that demonstrate various aspects of process management in Unix-like operating systems. These programs illustrate the use of system calls such as fork, getpid, and getppid to create and manage processes. Each file showcases different aspects of process creation, process hierarchy, and inter-process communication.

Key Features

• Process Creation: Examples of creating new processes using the fork system call.
• Process Hierarchy: Demonstrations of parent-child relationships between processes.
• Process Identification: Usage of process identifiers (PID) to manage and track processes.
• Process Synchronization: Basic examples of synchronizing processes using sleep and exit functions.

Files

1. A1P5.c

   • Demonstrates process creation and variable sharing between parent and child processes.
   • Key Code Snippet:

     #include <stdio.h>
     #include <unistd.h>
     
     int var = 50;
     
     int main() {
         pid_t pidc;
         printf("** Proceso PID = %d comienza **\n", getpid());
         pidc = fork();
         printf("Proceso PID = %d, pidC = %d ejecutándose\n", getpid(), pidc);
         if(pidc > 0) {
             var = 60;
         }
         else if(pidc == 0) {
             var = 40;
         }
         while(1) {
             sleep(2);
             printf("Procedimiento PID %d, var = %d ejecutándose\n", getpid(), var);
         }
     }

     This code creates a child process and demonstrates how the parent and child processes can modify a shared variable differently.

2. A2P5.c

   • Illustrates basic process creation and differentiation between parent and child processes.
   • Key Code Snippet:

     #include <stdio.h>
     #include <unistd.h>
     
     int main() {
         switch(fork()) {
             case -1:
                 printf("Error\n"); break;
             case 0:
                 printf("Proceso hijo\n"); break;
             default:
                 printf("El proceso padre\n");
         }
     }

     This code uses a switch statement to differentiate actions between the parent and child processes created by fork.

3. A3P5.c

   • Demonstrates process creation and hierarchical relationship between parent and child processes.
   • Key Code Snippet:

     #include <stdio.h>
     #include <stdlib.h>
     #include <sys/types.h>
     #include <unistd.h>
     
     int main() {
         system("clear");
         fprintf(stderr, "Inicia el programa con Proceso Padre: %ld\n", (long)getpid());
     
         if(fork() == 0) {
             fprintf(stderr, "\nInicia el hijo con PID: %ld y Padre PID: %ld\n", (long)getpid(), (long)getppid());
             sleep(1);
             fprintf(stderr, "\nNuevamente el hijo con PID: %ld y Padre PID: %ld\n", (long)getpid(), (long)getppid());
         } else {
             fprintf(stderr, "\nContinua el padre PID: %ld\n", (long)getpid());
             sleep(1);
             fprintf(stderr, "\nAhora finalizará el padre con PID: %ld\n", (long)getpid());
             exit(0);
         }
         exit(0);
     }

     This code shows how the child process gets the PID of its parent and demonstrates the hierarchical relationship between them.

4. A4P5.c

   • Demonstrates process creation and termination, and printing process details.
   • Key Code Snippet:

     #include <stdio.h>
     #include <stdlib.h>
     #include <sys/types.h>
     #include <unistd.h>
     
     int main() {
         int i;
     
         system("clear");
         for (i = 0; i < 4; i++) {
             if(fork())
                 break;
             fprintf(stderr, "\nProceso %i con PID: %ld\tPadre PID: %ld", i, (long)getpid(), (long)getppid());
         }
         fprintf(stderr, "\n\nFinalizado Proceso PID: %ld\n", (long)getpid());
         sleep(1);
         exit(0);
     }

     This code creates multiple child processes and prints their PIDs along with their parent's PID.

How to Use

1. Compilation: Each C file can be compiled using a C compiler such as gcc.

   gcc A1P5.c -o A1P5
   gcc A2P5.c -o A2P5
   gcc A3P5.c -o A3P5
   gcc A4P5.c -o A4P5

2. Execution: Run the compiled programs to see the output of process management operations.

   ./A1P5
   ./A2P5
   ./A3P5
   ./A4P5