How to Create Your Own Command in C

Program 1

#include<stdio.h>
#include<conio.h>
int main(int argc,char *argv[])
{
    if(argc==2)
    {
      FILE *fp=NULL;
      fp=fopen(argv[1],"r");
      if(fp==NULL)
        printf("File not found");
    else
    {
          char ch;
          while(((ch=fgetc(fp))!=EOF))
          {
              printf("%c",ch);
          }
          fclose(fp);
    }

    }
    else
      printf("Invalid command...."); 


}