Mini Shell

/* Standard include files. stdio.h is required. */
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <locale.h>

/* Used for select(2) */
#include <sys/types.h>
#include <sys/select.h>

#include <signal.h>

#include <errno.h>
#include <stdio.h>

/* Standard readline include files. */
#if defined (READLINE_LIBRARY)
#  include "readline.h"
#  include "history.h"
#else
#  include <readline/readline.h>
#  include <readline/history.h>
#endif

extern int errno;

static void cb_linehandler (char *);
static void signandler (int);

int running, sigwinch_received;
const char *prompt = "rltest$ ";

/* Handle SIGWINCH and window size changes when readline is not active and
   reading a character. */
static void
sighandler (int sig)
{
  sigwinch_received = 1;
}

/* Callback function called for each line when accept-line executed, EOF
   seen, or EOF character read.  This sets a flag and returns; it could
   also call exit(3). */
static void
cb_linehandler (char *line)
{
  /* Can use ^D (stty eof) or `exit' to exit. */
  if (line == NULL || strcmp (line, "exit") == 0)
    {
      if (line == 0)
        printf ("\n");
      printf ("exit\n");
      /* This function needs to be called to reset the terminal settings,
	 and calling it from the line handler keeps one extra prompt from
	 being displayed. */
      rl_callback_handler_remove ();

      running = 0;
    }
  else
    {
      if (*line)
	add_history (line);
      printf ("input line: %s\n", line);
      free (line);
    }
}

int
main (int c, char **v)
{
  fd_set fds;
  int r;


  setlocale (LC_ALL, "");

  /* Handle SIGWINCH */
  signal (SIGWINCH, sighandler);
  
  /* Install the line handler. */
  rl_callback_handler_install (prompt, cb_linehandler);

  /* Enter a simple event loop.  This waits until something is available
     to read on readline's input stream (defaults to standard input) and
     calls the builtin character read callback to read it.  It does not
     have to modify the user's terminal settings. */
  running = 1;
  while (running)
    {
      FD_ZERO (&fds);
      FD_SET (fileno (rl_instream), &fds);    

      r = select (FD_SETSIZE, &fds, NULL, NULL, NULL);
      if (r < 0 && errno != EINTR)
	{
	  perror ("rltest: select");
	  rl_callback_handler_remove ();
	  break;
	}
      if (sigwinch_received)
	{
	  rl_resize_terminal ();
	  sigwinch_received = 0;
	}
      if (r < 0)
	continue;

      if (FD_ISSET (fileno (rl_instream), &fds))
	rl_callback_read_char ();
    }

  printf ("rltest: Event loop has exited\n");
  return 0;
}