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

Copyright (C) 1987, 1989, 1991 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 1, or (at your option) any later
version.

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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, 675 Mass Ave, Cambridge, MA 02139, USA.

$PRODUCES help.c

$BUILTIN help
$FUNCTION help_builtin
$DEPENDS_ON HELP_BUILTIN
$SHORT_DOC help [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.
$END

#include <config.h>

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

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif

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

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

extern void builtin_error ();
extern void builtin_usage ();

static  void show_builtin_command_help ();

/* 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, j;
  char *pattern, *name;
  int plen, match_found;

  /* Placeholder for future options. */
  reset_internal_getopt ();
  while ((i = internal_getopt (list, "")) != -1)
    {
      switch (i)
	{
	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))
    {
      printf ("Shell commands matching keyword%s `", list->next ? "s" : "");
      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) ||
	      (fnmatch (pattern, name, 0) != FNM_NOMATCH))
	    {
	      printf ("%s: %s\n", name, shell_builtins[i].short_doc);

	      for (j = 0; shell_builtins[i].long_doc[j]; j++)
		printf ("    %s\n", shell_builtins[i].long_doc[j]);

	      match_found++;
	    }
	}
    }

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

  fflush (stdout);
  return (EXECUTION_SUCCESS);
}

static void
show_builtin_command_help ()
{
  int i, j;
  char blurb[36];

  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\
\n\
A star (*) next to a name means that the command is disabled.\n\
\n");

  for (i = 0; i < num_shell_builtins; i++)
    {
      QUIT;
      blurb[0] = (shell_builtins[i].flags & BUILTIN_ENABLED) ? ' ' : '*';
      strncpy (blurb + 1, shell_builtins[i].short_doc, 34);
      blurb[35] = '\0';
      printf ("%s", blurb);

      if (i % 2)
	printf ("\n");
      else
	for (j = strlen (blurb); j < 35; j++)
	  putc (' ', stdout);
    }
  if (i % 2)
    printf ("\n");
}
#endif /* HELP_BUILTIN */