decho.c

This is to bulid a sample linux shell.

// program to echo strings

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
main(int argc,char *argv[10])
{
   int i; 
   char token[15],ch;
   
  if((argc==2)&&(argv[1][0]=='$'))//if the commend contain $____
  {   
       strcpy(token,argv[0]); //reconstruct the commond and excecute
       strcat(token," ");
       strcat(token,argv[1]);
       system(token); 
       exit(0);
  }
  for(i=1;i<argc;i++)
  {
    printf("%s ",argv[i]);          //except arg(commond) print all arguments in single line
  }
   printf("\n");        //back to control;
}