@ignore
This file documents the user interface to the GNU History library.
-Copyright (C) 1988, 1991, 1994, 1996 Free Software Foundation, Inc.
+Copyright (C) 1988-2002 Free Software Foundation, Inc.
Authored by Brian Fox and Chet Ramey.
Permission is granted to make and distribute verbatim copies of this manual
@chapter Programming with GNU History
This chapter describes how to interface programs that you write
-with the GNU History Library.
+with the @sc{gnu} History Library.
It should be considered a technical guide.
-For information on the interactive use of GNU History, @pxref{Using
+For information on the interactive use of @sc{gnu} History, @pxref{Using
History Interactively}.
@menu
@node Introduction to History
@section Introduction to History
-Many programs read input from the user a line at a time. The GNU History
-library is able to keep track of those lines, associate arbitrary data with
-each line, and utilize information from previous lines in composing new
-ones.
+Many programs read input from the user a line at a time. The @sc{gnu}
+History library is able to keep track of those lines, associate arbitrary
+data with each line, and utilize information from previous lines in
+composing new ones.
The programmer using the History library has available functions
for remembering lines on a history list, associating arbitrary data
declared as follows:
@example
+typedef void *histdata_t;
+
typedef struct _hist_entry @{
char *line;
- char *data;
+ histdata_t data;
@} HIST_ENTRY;
@end example
The state of the History library is encapsulated into a single structure:
@example
-/* A structure used to pass the current state of the history stuff around. */
+/*
+ * A structure used to pass around the current state of the history.
+ */
typedef struct _hist_state @{
- HIST_ENTRY **entries; /* Pointer to the entries themselves. */
- int offset; /* The location pointer within this array. */
- int length; /* Number of elements within this array. */
- int size; /* Number of slots allocated to this array. */
+ HIST_ENTRY **entries; /* Pointer to the entries themselves. */
+ int offset; /* The location pointer within this array. */
+ int length; /* Number of elements within this array. */
+ int size; /* Number of slots allocated to this array. */
int flags;
@} HISTORY_STATE;
@end example
@section History Functions
This section describes the calling sequence for the various functions
-present in GNU History.
+exported by the @sc{gnu} History library.
@menu
* Initializing History and State Management:: Functions to call when you
the state of the History library when you want to use the history
functions in your program.
-@deftypefun void using_history ()
+@deftypefun void using_history (void)
Begin a session in which the history functions might be used. This
initializes the interactive variables.
@end deftypefun
-@deftypefun {HISTORY_STATE *} history_get_history_state ()
+@deftypefun {HISTORY_STATE *} history_get_history_state (void)
Return a structure describing the current state of the input history.
@end deftypefun
These functions manage individual entries on the history list, or set
parameters managing the list itself.
-@deftypefun void add_history (char *string)
+@deftypefun void add_history (const char *string)
Place @var{string} at the end of the history list. The associated data
field (if any) is set to @code{NULL}.
@end deftypefun
and containing structure.
@end deftypefun
-@deftypefun {HIST_ENTRY *} replace_history_entry (int which, char *line, char *data)
+@deftypefun {HIST_ENTRY *} replace_history_entry (int which, const char *line, histdata_t data)
Make the history entry at offset @var{which} have @var{line} and @var{data}.
This returns the old entry so you can dispose of the data. In the case
of an invalid @var{which}, a @code{NULL} pointer is returned.
@end deftypefun
-@deftypefun void clear_history ()
+@deftypefun void clear_history (void)
Clear the history list by deleting all the entries.
@end deftypefun
Stifle the history list, remembering only the last @var{max} entries.
@end deftypefun
-@deftypefun int unstifle_history ()
-Stop stifling the history. This returns the previous amount the
-history was stifled. The value is positive if the history was
+@deftypefun int unstifle_history (void)
+Stop stifling the history. This returns the previously-set
+maximum number of history entries (as set by @code{stifle_history()}).
+The value is positive if the history was
stifled, negative if it wasn't.
@end deftypefun
-@deftypefun int history_is_stifled ()
+@deftypefun int history_is_stifled (void)
Returns non-zero if the history is stifled, zero if it is not.
@end deftypefun
These functions return information about the entire history list or
individual list entries.
-@deftypefun {HIST_ENTRY **} history_list ()
-Return a @code{NULL} terminated array of @code{HIST_ENTRY} which is the
+@deftypefun {HIST_ENTRY **} history_list (void)
+Return a @code{NULL} terminated array of @code{HIST_ENTRY *} which is the
current input history. Element 0 of this list is the beginning of time.
If there is no history, return @code{NULL}.
@end deftypefun
-@deftypefun int where_history ()
+@deftypefun int where_history (void)
Returns the offset of the current history element.
@end deftypefun
-@deftypefun {HIST_ENTRY *} current_history ()
+@deftypefun {HIST_ENTRY *} current_history (void)
Return the history entry at the current position, as determined by
-@code{where_history ()}. If there is no entry there, return a @code{NULL}
+@code{where_history()}. If there is no entry there, return a @code{NULL}
pointer.
@end deftypefun
@deftypefun {HIST_ENTRY *} history_get (int offset)
Return the history entry at position @var{offset}, starting from
-@code{history_base}. If there is no entry there, or if @var{offset}
+@code{history_base} (@pxref{History Variables}).
+If there is no entry there, or if @var{offset}
is greater than the history length, return a @code{NULL} pointer.
@end deftypefun
-@deftypefun int history_total_bytes ()
+@deftypefun int history_total_bytes (void)
Return the number of bytes that the primary history entries are using.
This function returns the sum of the lengths of all the lines in the
history.
set or changed.
@deftypefun int history_set_pos (int pos)
-Set the position in the history list to @var{pos}, an absolute index
+Set the current history offset to @var{pos}, an absolute index
into the list.
+Returns 1 on success, 0 if @var{pos} is less than zero or greater
+than the number of history entries.
@end deftypefun
-@deftypefun {HIST_ENTRY *} previous_history ()
+@deftypefun {HIST_ENTRY *} previous_history (void)
Back up the current history offset to the previous history entry, and
return a pointer to that entry. If there is no previous entry, return
a @code{NULL} pointer.
@end deftypefun
-@deftypefun {HIST_ENTRY *} next_history ()
+@deftypefun {HIST_ENTRY *} next_history (void)
Move the current history offset forward to the next history entry, and
return the a pointer to that entry. If there is no next entry, return
a @code{NULL} pointer.
meaning that the string must match at the beginning of the history entry.
@cindex anchored search
-@deftypefun int history_search (char *string, int direction)
-Search the history for @var{string}, starting at the current history
-offset. If @var{direction} < 0, then the search is through previous entries,
-else through subsequent. If @var{string} is found, then
+@deftypefun int history_search (const char *string, int direction)
+Search the history for @var{string}, starting at the current history offset.
+If @var{direction} is less than 0, then the search is through
+previous entries, otherwise through subsequent entries.
+If @var{string} is found, then
the current history index is set to that history entry, and the value
returned is the offset in the line of the entry where
@var{string} was found. Otherwise, nothing is changed, and a -1 is
returned.
@end deftypefun
-@deftypefun int history_search_prefix (char *string, int direction)
+@deftypefun int history_search_prefix (const char *string, int direction)
Search the history for @var{string}, starting at the current history
offset. The search is anchored: matching lines must begin with
-@var{string}. If @var{direction} < 0, then the search is through previous
-entries, else through subsequent. If @var{string} is found, then the
+@var{string}. If @var{direction} is less than 0, then the search is
+through previous entries, otherwise through subsequent entries.
+If @var{string} is found, then the
current history index is set to that entry, and the return value is 0.
Otherwise, nothing is changed, and a -1 is returned.
@end deftypefun
-@deftypefun int history_search_pos (char *string, int direction, int pos)
+@deftypefun int history_search_pos (const char *string, int direction, int pos)
Search for @var{string} in the history list, starting at @var{pos}, an
absolute index into the list. If @var{direction} is negative, the search
proceeds backward from @var{pos}, otherwise forward. Returns the absolute
The History library can read the history from and write it to a file.
This section documents the functions for managing a history file.
-@deftypefun int read_history (char *filename)
-Add the contents of @var{filename} to the history list, a line at a
-time. If @var{filename} is @code{NULL}, then read from
-@file{~/.history}. Returns 0 if successful, or errno if not.
+@deftypefun int read_history (const char *filename)
+Add the contents of @var{filename} to the history list, a line at a time.
+If @var{filename} is @code{NULL}, then read from @file{~/.history}.
+Returns 0 if successful, or @code{errno} if not.
@end deftypefun
-@deftypefun int read_history_range (char *filename, int from, int to)
+@deftypefun int read_history_range (const char *filename, int from, int to)
Read a range of lines from @var{filename}, adding them to the history list.
-Start reading at line @var{from} and end at @var{to}. If
-@var{from} is zero, start at the beginning. If @var{to} is less than
+Start reading at line @var{from} and end at @var{to}.
+If @var{from} is zero, start at the beginning. If @var{to} is less than
@var{from}, then read until the end of the file. If @var{filename} is
@code{NULL}, then read from @file{~/.history}. Returns 0 if successful,
or @code{errno} if not.
@end deftypefun
-@deftypefun int write_history (char *filename)
+@deftypefun int write_history (const char *filename)
Write the current history to @var{filename}, overwriting @var{filename}
-if necessary. If @var{filename} is
-@code{NULL}, then write the history list to @file{~/.history}. Values
-returned are as in @code{read_history ()}.
+if necessary.
+If @var{filename} is @code{NULL}, then write the history list to
+@file{~/.history}.
+Returns 0 on success, or @code{errno} on a read or write error.
@end deftypefun
-@deftypefun int append_history (int nelements, char *filename)
+@deftypefun int append_history (int nelements, const char *filename)
Append the last @var{nelements} of the history list to @var{filename}.
+If @var{filename} is @code{NULL}, then append to @file{~/.history}.
+Returns 0 on success, or @code{errno} on a read or write error.
@end deftypefun
-@deftypefun int history_truncate_file (char *filename, int nlines)
+@deftypefun int history_truncate_file (const char *filename, int nlines)
Truncate the history file @var{filename}, leaving only the last
@var{nlines} lines.
+If @var{filename} is @code{NULL}, then @file{~/.history} is truncated.
+Returns 0 on success, or @code{errno} on failure.
@end deftypefun
@node History Expansion
@subsection History Expansion
-These functions implement @code{csh}-like history expansion.
+These functions implement history expansion.
@deftypefun int history_expand (char *string, char **output)
Expand @var{string}, placing the result into @var{output}, a pointer
@table @code
@item 0
If no expansions took place (or, if the only change in
-the text was the de-slashifying of the history expansion
+the text was the removal of escape characters preceding the history expansion
character);
@item 1
if expansions did take place;
error message.
@end deftypefun
-@deftypefun {char *} history_arg_extract (int first, int last, char *string)
-Extract a string segment consisting of the @var{first} through @var{last}
-arguments present in @var{string}. Arguments are broken up as in Bash.
-@end deftypefun
-
-@deftypefun {char *} get_history_event (char *string, int *cindex, int qchar)
+@deftypefun {char *} get_history_event (const char *string, int *cindex, int qchar)
Returns the text of the history event beginning at @var{string} +
@var{*cindex}. @var{*cindex} is modified to point to after the event
specifier. At function entry, @var{cindex} points to the index into
to the ``normal'' terminating characters.
@end deftypefun
-@deftypefun {char **} history_tokenize (char *string)
+@deftypefun {char **} history_tokenize (const char *string)
Return an array of tokens parsed out of @var{string}, much as the
-shell might. The tokens are split on white space and on the
-characters @code{()<>;&|$}, and shell quoting conventions are
-obeyed.
+shell might. The tokens are split on the characters in the
+@var{history_word_delimiters} variable,
+and shell quoting conventions are obeyed.
+@end deftypefun
+
+@deftypefun {char *} history_arg_extract (int first, int last, const char *string)
+Extract a string segment consisting of the @var{first} through @var{last}
+arguments present in @var{string}. Arguments are split using
+@code{history_tokenize}.
@end deftypefun
@node History Variables
@section History Variables
-This section describes the externally visible variables exported by
-the GNU History Library.
+This section describes the externally-visible variables exported by
+the @sc{gnu} History Library.
@deftypevar int history_base
The logical offset of the first entry in the history list.
The number of entries currently stored in the history list.
@end deftypevar
-@deftypevar int max_input_history
+@deftypevar int history_max_entries
The maximum number of history entries. This must be changed using
-@code{stifle_history ()}.
+@code{stifle_history()}.
@end deftypevar
@deftypevar char history_expansion_char
-The character that starts a history event. The default is @samp{!}.
+The character that introduces a history event. The default is @samp{!}.
+Setting this to 0 inhibits history expansion.
@end deftypevar
@deftypevar char history_subst_char
This is disabled by default.
@end deftypevar
+@deftypevar {char *} history_word_delimiters
+The characters that separate tokens for @code{history_tokenize()}.
+The default value is @code{" \t\n()<>;&|"}.
+@end deftypevar
+
@deftypevar {char *} history_no_expand_chars
The list of characters which inhibit history expansion if found immediately
-following @var{history_expansion_char}. The default is whitespace and
-@samp{=}.
+following @var{history_expansion_char}. The default is space, tab, newline,
+carriage return, and @samp{=}.
@end deftypevar
@deftypevar {char *} history_search_delimiter_chars
The list of additional characters which can delimit a history search
-string, in addition to whitespace, @samp{:} and @samp{?} in the case of
+string, in addition to space, TAB, @samp{:} and @samp{?} in the case of
a substring search. The default is empty.
@end deftypevar
character. The default value is 0.
@end deftypevar
-@deftypevar {Function *} history_inhibit_expansion_function
+@deftypevar {rl_linebuf_func_t *} history_inhibit_expansion_function
This should be set to the address of a function that takes two arguments:
-a @code{char *} (@var{string}) and an integer index into that string (@var{i}).
+a @code{char *} (@var{string})
+and an @code{int} index into that string (@var{i}).
It should return a non-zero value if the history expansion starting at
@var{string[i]} should not be performed; zero if the expansion should
be done.
It is intended for use by applications like Bash that use the history
expansion character for additional purposes.
-By default, this variable is set to NULL.
+By default, this variable is set to @code{NULL}.
@end deftypevar
@node History Programming Example
@section History Programming Example
-The following program demonstrates simple use of the GNU History Library.
+The following program demonstrates simple use of the @sc{gnu} History Library.
@smallexample
-main ()
+#include <stdio.h>
+#include <readline/history.h>
+
+main (argc, argv)
+ int argc;
+ char **argv;
@{
char line[1024], *t;
int len, done = 0;
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