mysh.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


//function to get input from user
char*  repl_loop()
{
    char *line = malloc(1024);
    
    while(1)
    {
    do 
    {
    printf("adansh> ");
    fgets(line,1024,stdin);
    if(line == NULL)
    {
        perror("Memory allocation failed\n");
        exit(0);
    }
    }while(line  == NULL || line[0] == '\n');

    printf("You entered: %s", line);
    return line;
    }
    free(line);
}

//function to interprate user input
char* interpret(char* line)
{
    char *delim = " \t\r\n\a";
    char *token;
    token = strtok(line, delim);
    while (token != NULL)
    {
        token = strtok(NULL, delim);
    }

    return token;
}

//function to execute commands
void execute(char **args)
{
    if (args == NULL)
    {
        perror("No command entered\n");
        return;
    }

    //forking a child process
    pid_t pid = fork();
    if (pid < 0)
    {
        perror("Fork failed");
        return;
    }

    if (pid == 0 )
    {
        //child process
        if (execvp(args[0], args) == -1)
        {
            perror("Execution failed");
        }
        exit(EXIT_FAILURE);
    }

    else 
    {
        //This is the parent process - wait for the child to complete
        int status;
        do 
        {
            waitpid(pid, &status, WUNTRACED);
        } while (!WIFEXITED(status) && !WIFSIGNALED(status));
    }
}


//main function
int main()
{
    char *input = repl_loop();
    char *output =interpret(input);
    execute(output)
    free(input);

    return 0;
}