/* Compile: 
   cc -G isatty.c -o isatty.so -Kpic
   gcc -shared -o isatty.so isatty.c

 * Use: 
   env LD_PRELOAD=./isatty.so cmd

 * Why:

   This is a sample C program: 

   #include <stdio.h>
   main(argc, argv)
   int    argc;
   char **argv;
   {
     int c;
     while ( (c=getchar()) != EOF ) {
       putchar(c);
     }
   }

   It uses the following shared libraries: 

   $ ldd mi_cat
   libc.so.1 =>     /usr/lib/libc.so.1
   libdl.so.1 =>    /usr/lib/libdl.so.1

   libc.so.1 has a function _isatty which will test if the output is
   a tty, and then decide if to use buffer. 

   $ nm /usr/lib/libc.so.1 | grep isatty
     [3281]  |    247552|      71|FUNC |GLOB |0    |12     |_isatty
     [4400]  |    247552|      71|FUNC |WEAK |0    |12     |isatty
     [1394]  |         0|       0|FILE |LOCL |0    |ABS    |isatty.c

   LD_PRELOAD forces the C program to use preloaded version of _isatty
   which return 1 indicating it is tty though it may not be. This forces
   non-buffering. 
*/

_isatty(int fd) { return 1;}