This file is help.def, from which is created help.c.
It implements the builtin "help" in Bash.

Copyright (C) 1987-2006 Free Software Foundation, Inc.

This file is part of GNU Bash, the Bourne Again SHell.

Bash is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

Bash is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with Bash; see the file COPYING.  If not, write to the Free Software
Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.

$PRODUCES help.c

$BUILTIN help
$FUNCTION help_builtin
$DEPENDS_ON HELP_BUILTIN
$SHORT_DOC help [-s] [pattern ...]
Display helpful information about builtin commands.  If PATTERN is
specified, gives detailed help on all commands matching PATTERN,
otherwise a list of the builtins is printed.  The -s option
restricts the output for each builtin command matching PATTERN to
a short usage synopsis.
$END

#include <config.h>

#if defined (HELP_BUILTIN)
#include <stdio.h>

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include <errno.h>

#include <filecntl.h>

#include "../bashintl.h"

#include "../shell.h"
#include "../builtins.h"
#include "../pathexp.h"
#include "common.h"
#include "bashgetopt.h"

#include <glob/strmatch.h>
#include <glob/glob.h>

#ifndef errno
extern int errno;
#endif

static void show_builtin_command_help __P((void));
static void show_longdoc __P((int));

/* Print out a list of the known functions in the shell, and what they do.
   If LIST is supplied, print out the list which matches for each pattern
   specified. */
int
help_builtin (list)
     WORD_LIST *list;
{
  register int i;
  char *pattern, *name;
  int plen, match_found, sflag;

  sflag = 0;
  reset_internal_getopt ();
  while ((i = internal_getopt (list, "s")) != -1)
    {
      switch (i)
	{
	case 's':
	  sflag = 1;
	  break;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }
  list = loptend;

  if (list == 0)
    {
      show_shell_version (0);
      show_builtin_command_help ();
      return (EXECUTION_SUCCESS);
    }

  /* We should consider making `help bash' do something. */

  if (glob_pattern_p (list->word->word))
    {
      if (list->next)
	printf (_("Shell commands matching keywords `"));
      else
	printf (_("Shell commands matching keyword `"));
      print_word_list (list, ", ");
      printf ("'\n\n");
    }

  for (match_found = 0, pattern = ""; list; list = list->next)
    {
      pattern = list->word->word;
      plen = strlen (pattern);

      for (i = 0; name = shell_builtins[i].name; i++)
	{
	  QUIT;
	  if ((strncmp (pattern, name, plen) == 0) ||
	      (strmatch (pattern, name, FNMATCH_EXTFLAG) != FNM_NOMATCH))
	    {
	      printf ("%s: %s\n", name, shell_builtins[i].short_doc);

	      if (sflag == 0)
		show_longdoc (i);

	      match_found++;
	    }
	}
    }

  if (match_found == 0)
    {
      builtin_error (_("no help topics match `%s'.  Try `help help' or `man -k %s' or `info %s'."), pattern, pattern, pattern);
      return (EXECUTION_FAILURE);
    }

  fflush (stdout);
  return (EXECUTION_SUCCESS);
}

/* By convention, enforced by mkbuiltins.c, if separate help files are being
   used, the long_doc array contains one string -- the full pathname of the
   help file for this builtin.  */
static void
show_longdoc (i)
     int i;
{
  register int j;
  char * const *doc;
  int fd;

  doc = shell_builtins[i].long_doc;

  if (doc && doc[0] && *doc[0] == '/' && doc[1] == (char *)NULL)
    {
      fd = open (doc[0], O_RDONLY);
      if (fd == -1)
	{
	  builtin_error (_("%s: cannot open: %s"), doc[0], strerror (errno));
	  return;
	}
      zcatfd (fd, 1, doc[0]);
      close (fd);
    }
  else
    for (j = 0; doc[j]; j++)
      printf ("%*s%s\n", BASE_INDENT, " ", _(doc[j]));
}

static void
show_builtin_command_help ()
{
  int i, j;
  int height, width;
  char *t, blurb[128];

  printf (
_("These shell commands are defined internally.  Type `help' to see this list.\n\
Type `help name' to find out more about the function `name'.\n\
Use `info bash' to find out more about the shell in general.\n\
Use `man -k' or `info' to find out more about commands not in this list.\n\
\n\
A star (*) next to a name means that the command is disabled.\n\
\n"));

  t = get_string_value ("COLUMNS");
  width = (t && *t) ? atoi (t) : 80;
  if (width <= 0)
    width = 80;

  width /= 2;
  if (width > sizeof (blurb))
    width = sizeof (blurb);
  height = (num_shell_builtins + 1) / 2;	/* number of rows */

  for (i = 0; i < height; i++)
    {
      QUIT;

      /* first column */
      blurb[0] = (shell_builtins[i].flags & BUILTIN_ENABLED) ? ' ' : '*';
      strncpy (blurb + 1, shell_builtins[i].short_doc, width - 2);
      blurb[width - 2] = '>';		/* indicate truncation */
      blurb[width - 1] = '\0';
      printf ("%s", blurb);
      if (((i << 1) >= num_shell_builtins) || (i+height >= num_shell_builtins))
	{
	  printf ("\n");
	  break;
	}

      /* two spaces */
      for (j = strlen (blurb); j < width; j++)
        putc (' ', stdout);

      /* second column */
      blurb[0] = (shell_builtins[i+height].flags & BUILTIN_ENABLED) ? ' ' : '*';
      strncpy (blurb + 1, shell_builtins[i+height].short_doc, width - 3);
      blurb[width - 3] = '>';		/* indicate truncation */
      blurb[width - 2] = '\0';
      printf ("%s\n", blurb);
    }
}
#endif /* HELP_BUILTIN */
