Simple emulation of command-line bash functionality

With Linux for a while, and consistently enter commands under bash but I've always wondered how this bash knows what commands I want to enter, so I use my knowledge to temporarily imitate some bash features and continue to refine the functionality.

First time Version:

/**********************************************************************   * Copyright (c) 2015,wk Studios * Filename:   main.c * compiler:gcc,vs,vc6.0  Win32   * AUTHOR:WK   * time:2015 29 4 ************************* /#include <stdio.h> #include <stdlib.h> #include < string.h> int main () {char cmd[128]={0}; while (1) {printf ("Input command:"); scanf ("%s", cmd); if (0==strcmp (cmd, "help")) {printf ("command\n");} else if (0== (cmd, "Quit") &&strcmp (cmd, "q" )) {exit (0);} else {printf ("Command not found\n");}}}

Second version:

/**********************************************************************   * Copyright (c) 2015,wk Studios * Filename:   bash.h * compiler:gcc,vs,vc6.0  Win32   * AUTHOR:WK   * time:2015 29 4 ************************* /#include <stdio.h> #include <stdlib.h> #include < string.h> #ifndef _bash_h#define _bash_h#define cmd_max_len 128#define desc_len  1024#define CMD_NUM   10int Help (); int quit (); int show (); typedef struct datanode{    char *cmd;    char *desc;    Int (*handler) ();//function pointer    struct DataNode *next;} tdatanode;//  T indicates that typedef defines a static Tdatanode head[]=//linked list array {    {"Help", "This is help cmd", help,&head[1]},    {"Version", "menu Program v1.0", Null,&head[2]},    {"Quit", "This is quit cmd", quit,null}//can add commands to the array, here are only a few commands};tdatanode* find (tdatanode* head,char *cmd); #endif

/**********************************************************************   * Copyright (c) 2015,wk Studios * Filename:   main.c * compiler:gcc,vs,vc6.0  Win32   * AUTHOR:WK   * time:2015 29 4 ************************* /#include "bash.h" tdatanode*  find (Tdatanode *head,char *cmd) { if (head==null| | cmd==null) {return NULL;    } Tdatanode *p=head;while (p!=null) {if (strcmp (p->cmd,cmd) ==0) {return p;} P=p->next;} return NULL;} int Show (Tdatanode *head) {tdatanode *p=head;printf ("menu list:\n"), while (P!=null) {printf ("%s-%s\n", p->cmd,p- >DESC);p =p->next;} return 1;} int Help ()//Print all commands {    show (head); return 1;} int quit () {exit (0);}

/**********************************************************************   * Copyright (c) 2015,wk Studios * Filename:   main.c * compiler:gcc,vs,vc6.0  Win32   * AUTHOR:WK   * time:2015 29 4 ************************* /#include "bash,h" int main () {while (1) {    char cmd[cmd_max_len]; printf ("Input a Command number>"), scanf ("%s", cmd), Tdatanode *p=find (Head,cmd), if (p==null) {printf ("command not Found!\n "); continue;} printf ("%s-%s\n", P->CMD,P->DESC); if (p->handler! = NULL)//a somewhat polymorphic meaning calls the same handler effect differently {            p->handler (); /functiom Point}}return 0;}

Simple emulation of command-line bash functionality