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HISTORY(3) HISTORY(3)
NNAAMMEE
history - GNU History Library
CCOOPPYYRRIIGGHHTT
The GNU History Library is Copyright (C) 1989-2002 by the
Free Software Foundation, Inc.
DDEESSCCRRIIPPTTIIOONN
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 uti-
lize information from previous lines in composing new
ones.
HHIISSTTOORRYY EEXXPPAANNSSIIOONN
The history library supports a history expansion feature
that is identical to the history expansion in bbaasshh.. This
section describes what syntax features are available.
History expansions introduce words from the history list
into the input stream, making it easy to repeat commands,
insert the arguments to a previous command into the cur-
rent input line, or fix errors in previous commands
quickly.
History expansion is usually performed immediately after a
complete line is read. It takes place in two parts. The
first is to determine which line from the history list to
use during substitution. The second is to select portions
of that line for inclusion into the current one. The line
selected from the history is the _e_v_e_n_t, and the portions
of that line that are acted upon are _w_o_r_d_s. Various _m_o_d_i_-
_f_i_e_r_s are available to manipulate the selected words. The
line is broken into words in the same fashion as bbaasshh does
when reading input, so that several words that would oth-
erwise be separated are considered one word when sur-
rounded by quotes (see the description of hhiissttoorryy__ttookk--
eenniizzee(()) below). History expansions are introduced by the
appearance of the history expansion character, which is !!
by default. Only backslash (\\) and single quotes can
quote the history expansion character.
EEvveenntt DDeessiiggnnaattoorrss
An event designator is a reference to a command line entry
in the history list.
!! Start a history substitution, except when followed
by a bbllaannkk, newline, = or (.
!!_n Refer to command line _n.
!!--_n Refer to the current command line minus _n.
!!!! Refer to the previous command. This is a synonym
for `!-1'.
GNU History 4.3 2002 January 31 1
HISTORY(3) HISTORY(3)
!!_s_t_r_i_n_g
Refer to the most recent command starting with
_s_t_r_i_n_g.
!!??_s_t_r_i_n_g[[??]]
Refer to the most recent command containing _s_t_r_i_n_g.
The trailing ?? may be omitted if _s_t_r_i_n_g is followed
immediately by a newline.
^^_s_t_r_i_n_g_1^^_s_t_r_i_n_g_2^^
Quick substitution. Repeat the last command,
replacing _s_t_r_i_n_g_1 with _s_t_r_i_n_g_2. Equivalent to
``!!:s/_s_t_r_i_n_g_1/_s_t_r_i_n_g_2/'' (see MMooddiiffiieerrss below).
!!## The entire command line typed so far.
WWoorrdd DDeessiiggnnaattoorrss
Word designators are used to select desired words from the
event. A :: separates the event specification from the
word designator. It may be omitted if the word designator
begins with a ^^, $$, **, --, or %%. Words are numbered from
the beginning of the line, with the first word being
denoted by 0 (zero). Words are inserted into the current
line separated by single spaces.
00 ((zzeerroo))
The zeroth word. For the shell, this is the com-
mand word.
_n The _nth word.
^^ The first argument. That is, word 1.
$$ The last argument.
%% The word matched by the most recent `?_s_t_r_i_n_g?'
search.
_x--_y A range of words; `-_y' abbreviates `0-_y'.
** All of the words but the zeroth. This is a synonym
for `_1_-_$'. It is not an error to use ** if there is
just one word in the event; the empty string is
returned in that case.
xx** Abbreviates _x_-_$.
xx-- Abbreviates _x_-_$ like xx**, but omits the last word.
If a word designator is supplied without an event specifi-
cation, the previous command is used as the event.
MMooddiiffiieerrss
After the optional word designator, there may appear a
sequence of one or more of the following modifiers, each
preceded by a `:'.
hh Remove a trailing file name component, leaving only
the head.
tt Remove all leading file name components, leaving
the tail.
rr Remove a trailing suffix of the form _._x_x_x, leaving
the basename.
ee Remove all but the trailing suffix.
pp Print the new command but do not execute it.
GNU History 4.3 2002 January 31 2
HISTORY(3) HISTORY(3)
qq Quote the substituted words, escaping further sub-
stitutions.
xx Quote the substituted words as with qq, but break
into words at bbllaannkkss and newlines.
ss//_o_l_d//_n_e_w//
Substitute _n_e_w for the first occurrence of _o_l_d in
the event line. Any delimiter can be used in place
of /. The final delimiter is optional if it is the
last character of the event line. The delimiter
may be quoted in _o_l_d and _n_e_w with a single back-
slash. If & appears in _n_e_w, it is replaced by _o_l_d.
A single backslash will quote the &. If _o_l_d is
null, it is set to the last _o_l_d substituted, or, if
no previous history substitutions took place, the
last _s_t_r_i_n_g in a !!??_s_t_r_i_n_g[[??]] search.
&& Repeat the previous substitution.
gg Cause changes to be applied over the entire event
line. This is used in conjunction with `::ss' (e.g.,
`::ggss//_o_l_d//_n_e_w//') or `::&&'. If used with `::ss', any
delimiter can be used in place of /, and the final
delimiter is optional if it is the last character
of the event line.
PPRROOGGRRAAMMMMIINNGG WWIITTHH HHIISSTTOORRYY FFUUNNCCTTIIOONNSS
This section describes how to use the History library in
other programs.
IInnttrroodduuccttiioonn ttoo HHiissttoorryy
The programmer using the History library has available
functions for remembering lines on a history list, associ-
ating arbitrary data with a line, removing lines from the
list, searching through the list for a line containing an
arbitrary text string, and referencing any line in the
list directly. In addition, a history _e_x_p_a_n_s_i_o_n function
is available which provides for a consistent user inter-
face across different programs.
The user using programs written with the History library
has the benefit of a consistent user interface with a set
of well-known commands for manipulating the text of previ-
ous lines and using that text in new commands. The basic
history manipulation commands are identical to the history
substitution provided by bbaasshh.
If the programmer desires, he can use the Readline
library, which includes some history manipulation by
default, and has the added advantage of command line edit-
ing.
Before declaring any functions using any functionality the
History library provides in other code, an application
writer should include the file _<_r_e_a_d_l_i_n_e_/_h_i_s_t_o_r_y_._h_> in any
file that uses the History library's features. It sup-
plies extern declarations for all of the library's public
GNU History 4.3 2002 January 31 3
HISTORY(3) HISTORY(3)
functions and variables, and declares all of the public
data structures.
HHiissttoorryy SSttoorraaggee
The history list is an array of history entries. A his-
tory entry is declared as follows:
_t_y_p_e_d_e_f _v_o_i_d _* hhiissttddaattaa__tt;;
typedef struct _hist_entry {
char *line;
histdata_t data;
} HIST_ENTRY;
The history list itself might therefore be declared as
_H_I_S_T___E_N_T_R_Y _*_* tthhee__hhiissttoorryy__lliisstt;;
The state of the History library is encapsulated into a
single structure:
/*
* 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. */
int flags;
} HISTORY_STATE;
If the flags member includes HHSS__SSTTIIFFLLEEDD, the history has
been stifled.
HHiissttoorryy FFuunnccttiioonnss
This section describes the calling sequence for the vari-
ous functions exported by the GNU History library.
IInniittiiaalliizziinngg HHiissttoorryy aanndd SSttaattee MMaannaaggeemmeenntt
This section describes functions used to initialize and
manage the state of the History library when you want to
use the history functions in your program.
_v_o_i_d uussiinngg__hhiissttoorryy (_v_o_i_d)
Begin a session in which the history functions might be
used. This initializes the interactive variables.
_H_I_S_T_O_R_Y___S_T_A_T_E _* hhiissttoorryy__ggeett__hhiissttoorryy__ssttaattee (_v_o_i_d)
Return a structure describing the current state of the
input history.
_v_o_i_d hhiissttoorryy__sseett__hhiissttoorryy__ssttaattee (_H_I_S_T_O_R_Y___S_T_A_T_E _*_s_t_a_t_e)
GNU History 4.3 2002 January 31 4
HISTORY(3) HISTORY(3)
Set the state of the history list according to _s_t_a_t_e.
HHiissttoorryy LLiisstt MMaannaaggeemmeenntt
These functions manage individual entries on the history
list, or set parameters managing the list itself.
_v_o_i_d aadddd__hhiissttoorryy (_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g)
Place _s_t_r_i_n_g at the end of the history list. The associ-
ated data field (if any) is set to NNUULLLL.
_H_I_S_T___E_N_T_R_Y _* rreemmoovvee__hhiissttoorryy (_i_n_t _w_h_i_c_h)
Remove history entry at offset _w_h_i_c_h from the history.
The removed element is returned so you can free the line,
data, and containing structure.
_H_I_S_T___E_N_T_R_Y _* rreeppllaaccee__hhiissttoorryy__eennttrryy (_i_n_t _w_h_i_c_h_, _c_o_n_s_t _c_h_a_r
_*_l_i_n_e_, _h_i_s_t_d_a_t_a___t _d_a_t_a)
Make the history entry at offset _w_h_i_c_h have _l_i_n_e and _d_a_t_a.
This returns the old entry so you can dispose of the data.
In the case of an invalid _w_h_i_c_h, a NNUULLLL pointer is
returned.
_v_o_i_d cclleeaarr__hhiissttoorryy (_v_o_i_d)
Clear the history list by deleting all the entries.
_v_o_i_d ssttiiffllee__hhiissttoorryy (_i_n_t _m_a_x)
Stifle the history list, remembering only the last _m_a_x
entries.
_i_n_t uunnssttiiffllee__hhiissttoorryy (_v_o_i_d)
Stop stifling the history. This returns the previously-
set maximum number of history entries (as set by ssttii--
ffllee__hhiissttoorryy(())). history was stifled. The value is posi-
tive if the history was stifled, negative if it wasn't.
_i_n_t hhiissttoorryy__iiss__ssttiifflleedd (_v_o_i_d)
Returns non-zero if the history is stifled, zero if it is
not.
IInnffoorrmmaattiioonn AAbboouutt tthhee HHiissttoorryy LLiisstt
These functions return information about the entire his-
tory list or individual list entries.
_H_I_S_T___E_N_T_R_Y _*_* hhiissttoorryy__lliisstt (_v_o_i_d)
Return a NNUULLLL terminated array of _H_I_S_T___E_N_T_R_Y _* which is
the current input history. Element 0 of this list is the
beginning of time. If there is no history, return NNUULLLL.
_i_n_t wwhheerree__hhiissttoorryy (_v_o_i_d)
Returns the offset of the current history element.
_H_I_S_T___E_N_T_R_Y _* ccuurrrreenntt__hhiissttoorryy (_v_o_i_d)
GNU History 4.3 2002 January 31 5
HISTORY(3) HISTORY(3)
Return the history entry at the current position, as
determined by wwhheerree__hhiissttoorryy(()). If there is no entry
there, return a NNUULLLL pointer.
_H_I_S_T___E_N_T_R_Y _* hhiissttoorryy__ggeett (_i_n_t _o_f_f_s_e_t)
Return the history entry at position _o_f_f_s_e_t, starting from
hhiissttoorryy__bbaassee. If there is no entry there, or if _o_f_f_s_e_t is
greater than the history length, return a NNUULLLL pointer.
_i_n_t hhiissttoorryy__ttoottaall__bbyytteess (_v_o_i_d)
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.
MMoovviinngg AArroouunndd tthhee HHiissttoorryy LLiisstt
These functions allow the current index into the history
list to be set or changed.
_i_n_t hhiissttoorryy__sseett__ppooss (_i_n_t _p_o_s)
Set the current history offset to _p_o_s, an absolute index
into the list. Returns 1 on success, 0 if _p_o_s is less
than zero or greater than the number of history entries.
_H_I_S_T___E_N_T_R_Y _* pprreevviioouuss__hhiissttoorryy (_v_o_i_d)
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 NNUULLLL pointer.
_H_I_S_T___E_N_T_R_Y _* nneexxtt__hhiissttoorryy (_v_o_i_d)
Move the current history offset forward to the next his-
tory entry, and return the a pointer to that entry. If
there is no next entry, return a NNUULLLL pointer.
SSeeaarrcchhiinngg tthhee HHiissttoorryy LLiisstt
These functions allow searching of the history list for
entries containing a specific string. Searching may be
performed both forward and backward from the current his-
tory position. The search may be _a_n_c_h_o_r_e_d, meaning that
the string must match at the beginning of the history
entry.
_i_n_t hhiissttoorryy__sseeaarrcchh (_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g_, _i_n_t _d_i_r_e_c_t_i_o_n)
Search the history for _s_t_r_i_n_g, starting at the current
history offset. If _d_i_r_e_c_t_i_o_n is less than 0, then the
search is through previous entries, otherwise through sub-
sequent entries. If _s_t_r_i_n_g 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
_s_t_r_i_n_g was found. Otherwise, nothing is changed, and a -1
is returned.
_i_n_t hhiissttoorryy__sseeaarrcchh__pprreeffiixx (_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g_, _i_n_t
GNU History 4.3 2002 January 31 6
HISTORY(3) HISTORY(3)
_d_i_r_e_c_t_i_o_n)
Search the history for _s_t_r_i_n_g, starting at the current
history offset. The search is anchored: matching lines
must begin with _s_t_r_i_n_g. If _d_i_r_e_c_t_i_o_n is less than 0, then
the search is through previous entries, otherwise through
subsequent entries. If _s_t_r_i_n_g 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.
_i_n_t hhiissttoorryy__sseeaarrcchh__ppooss (_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g_, _i_n_t _d_i_r_e_c_t_i_o_n_,
_i_n_t _p_o_s)
Search for _s_t_r_i_n_g in the history list, starting at _p_o_s, an
absolute index into the list. If _d_i_r_e_c_t_i_o_n is negative,
the search proceeds backward from _p_o_s, otherwise forward.
Returns the absolute index of the history element where
_s_t_r_i_n_g was found, or -1 otherwise.
MMaannaaggiinngg tthhee HHiissttoorryy FFiillee
The History library can read the history from and write it
to a file. This section documents the functions for man-
aging a history file.
_i_n_t rreeaadd__hhiissttoorryy (_c_o_n_s_t _c_h_a_r _*_f_i_l_e_n_a_m_e)
Add the contents of _f_i_l_e_n_a_m_e to the history list, a line
at a time. If _f_i_l_e_n_a_m_e is NNUULLLL, then read from _~_/_._h_i_s_-
_t_o_r_y. Returns 0 if successful, or eerrrrnnoo if not.
_i_n_t rreeaadd__hhiissttoorryy__rraannggee (_c_o_n_s_t _c_h_a_r _*_f_i_l_e_n_a_m_e_, _i_n_t _f_r_o_m_,
_i_n_t _t_o)
Read a range of lines from _f_i_l_e_n_a_m_e, adding them to the
history list. Start reading at line _f_r_o_m and end at _t_o.
If _f_r_o_m is zero, start at the beginning. If _t_o is less
than _f_r_o_m, then read until the end of the file. If _f_i_l_e_-
_n_a_m_e is NNUULLLL, then read from _~_/_._h_i_s_t_o_r_y. Returns 0 if
successful, or eerrrrnnoo if not.
_i_n_t wwrriittee__hhiissttoorryy (_c_o_n_s_t _c_h_a_r _*_f_i_l_e_n_a_m_e)
Write the current history to _f_i_l_e_n_a_m_e, overwriting _f_i_l_e_-
_n_a_m_e if necessary. If _f_i_l_e_n_a_m_e is NNUULLLL, then write the
history list to _~_/_._h_i_s_t_o_r_y. Returns 0 on success, or
eerrrrnnoo on a read or write error.
_i_n_t aappppeenndd__hhiissttoorryy (_i_n_t _n_e_l_e_m_e_n_t_s_, _c_o_n_s_t _c_h_a_r _*_f_i_l_e_n_a_m_e)
Append the last _n_e_l_e_m_e_n_t_s of the history list to _f_i_l_e_n_a_m_e.
If _f_i_l_e_n_a_m_e is NNUULLLL, then append to _~_/_._h_i_s_t_o_r_y. Returns 0
on success, or eerrrrnnoo on a read or write error.
_i_n_t hhiissttoorryy__ttrruunnccaattee__ffiillee (_c_o_n_s_t _c_h_a_r _*_f_i_l_e_n_a_m_e_, _i_n_t
_n_l_i_n_e_s)
Truncate the history file _f_i_l_e_n_a_m_e, leaving only the last
_n_l_i_n_e_s lines. If _f_i_l_e_n_a_m_e is NNUULLLL, then _~_/_._h_i_s_t_o_r_y is
GNU History 4.3 2002 January 31 7
HISTORY(3) HISTORY(3)
truncated. Returns 0 on success, or eerrrrnnoo on failure.
HHiissttoorryy EExxppaannssiioonn
These functions implement history expansion.
_i_n_t hhiissttoorryy__eexxppaanndd (_c_h_a_r _*_s_t_r_i_n_g_, _c_h_a_r _*_*_o_u_t_p_u_t)
Expand _s_t_r_i_n_g, placing the result into _o_u_t_p_u_t, a pointer
to a string. Returns:
0 If no expansions took place (or, if the only
change in the text was the removal of escape
characters preceding the history expansion
character);
1 if expansions did take place;
-1 if there was an error in expansion;
2 if the returned line should be displayed,
but not executed, as with the ::pp modifier.
If an error ocurred in expansion, then _o_u_t_p_u_t contains a
descriptive error message.
_c_h_a_r _* ggeett__hhiissttoorryy__eevveenntt (_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g_, _i_n_t _*_c_i_n_d_e_x_,
_i_n_t _q_c_h_a_r)
Returns the text of the history event beginning at _s_t_r_i_n_g
+ _*_c_i_n_d_e_x. _*_c_i_n_d_e_x is modified to point to after the
event specifier. At function entry, _c_i_n_d_e_x points to the
index into _s_t_r_i_n_g where the history event specification
begins. _q_c_h_a_r is a character that is allowed to end the
event specification in addition to the ``normal'' termi-
nating characters.
_c_h_a_r _*_* hhiissttoorryy__ttookkeenniizzee (_c_o_n_s_t _c_h_a_r _*_s_t_r_i_n_g)
Return an array of tokens parsed out of _s_t_r_i_n_g, much as
the shell might. The tokens are split on the characters
in the hhiissttoorryy__wwoorrdd__ddeelliimmiitteerrss variable, and shell quoting
conventions are obeyed.
_c_h_a_r _* hhiissttoorryy__aarrgg__eexxttrraacctt (_i_n_t _f_i_r_s_t_, _i_n_t _l_a_s_t_, _c_o_n_s_t
_c_h_a_r _*_s_t_r_i_n_g)
Extract a string segment consisting of the _f_i_r_s_t through
_l_a_s_t arguments present in _s_t_r_i_n_g. Arguments are split
using hhiissttoorryy__ttookkeenniizzee(()).
HHiissttoorryy VVaarriiaabblleess
This section describes the externally-visible variables
exported by the GNU History Library.
_i_n_t hhiissttoorryy__bbaassee
The logical offset of the first entry in the history list.
_i_n_t hhiissttoorryy__lleennggtthh
The number of entries currently stored in the history
list.
GNU History 4.3 2002 January 31 8
HISTORY(3) HISTORY(3)
_i_n_t hhiissttoorryy__mmaaxx__eennttrriieess
The maximum number of history entries. This must be
changed using ssttiiffllee__hhiissttoorryy(()).
_c_h_a_r hhiissttoorryy__eexxppaannssiioonn__cchhaarr
The character that introduces a history event. The
default is !!. Setting this to 0 inhibits history expan-
sion.
_c_h_a_r hhiissttoorryy__ssuubbsstt__cchhaarr
The character that invokes word substitution if found at
the start of a line. The default is ^^.
_c_h_a_r hhiissttoorryy__ccoommmmeenntt__cchhaarr
During tokenization, if this character is seen as the
first character of a word, then it and all subsequent
characters up to a newline are ignored, suppressing his-
tory expansion for the remainder of the line. This is
disabled by default.
_c_h_a_r _* hhiissttoorryy__wwoorrdd__ddeelliimmiitteerrss
The characters that separate tokens for hhiissttoorryy__ttookk--
eenniizzee(()). The default value is "" \\tt\\nn(())<<>>;;&&||"".
_c_h_a_r _* hhiissttoorryy__nnoo__eexxppaanndd__cchhaarrss
The list of characters which inhibit history expansion if
found immediately following hhiissttoorryy__eexxppaannssiioonn__cchhaarr. The
default is space, tab, newline, \\rr, and ==.
_c_h_a_r _* hhiissttoorryy__sseeaarrcchh__ddeelliimmiitteerr__cchhaarrss
The list of additional characters which can delimit a his-
tory search string, in addition to space, tab, _: and _? in
the case of a substring search. The default is empty.
_i_n_t hhiissttoorryy__qquuootteess__iinnhhiibbiitt__eexxppaannssiioonn
If non-zero, single-quoted words are not scanned for the
history expansion character. The default value is 0.
_r_l___l_i_n_e_b_u_f___f_u_n_c___t _* hhiissttoorryy__iinnhhiibbiitt__eexxppaannssiioonn__ffuunnccttiioonn
This should be set to the address of a function that takes
two arguments: a cchhaarr ** (_s_t_r_i_n_g) and an iinntt index into
that string (_i). It should return a non-zero value if the
history expansion starting at _s_t_r_i_n_g_[_i_] should not be per-
formed; zero if the expansion should be done. It is
intended for use by applications like bbaasshh that use the
history expansion character for additional purposes. By
default, this variable is set to NNUULLLL.
FFIILLEESS
_~_/_._h_i_s_t_o_r_y
Default filename for reading and writing saved his-
tory
GNU History 4.3 2002 January 31 9
HISTORY(3) HISTORY(3)
SSEEEE AALLSSOO
_T_h_e _G_n_u _R_e_a_d_l_i_n_e _L_i_b_r_a_r_y, Brian Fox and Chet Ramey
_T_h_e _G_n_u _H_i_s_t_o_r_y _L_i_b_r_a_r_y, Brian Fox and Chet Ramey
_b_a_s_h(1)
_r_e_a_d_l_i_n_e(3)
AAUUTTHHOORRSS
Brian Fox, Free Software Foundation
bfox@gnu.org
Chet Ramey, Case Western Reserve University
chet@ins.CWRU.Edu
BBUUGG RREEPPOORRTTSS
If you find a bug in the hhiissttoorryy library, you should
report it. But first, you should make sure that it really
is a bug, and that it appears in the latest version of the
hhiissttoorryy library that you have.
Once you have determined that a bug actually exists, mail
a bug report to _b_u_g_-_r_e_a_d_l_i_n_e@_g_n_u_._o_r_g. If you have a fix,
you are welcome to mail that as well! Suggestions and
`philosophical' bug reports may be mailed to _b_u_g_-_r_e_a_d_-
_l_i_n_e@_g_n_u_._o_r_g or posted to the Usenet newsgroup
ggnnuu..bbaasshh..bbuugg.
Comments and bug reports concerning this manual page
should be directed to _c_h_e_t_@_i_n_s_._C_W_R_U_._E_d_u.
GNU History 4.3 2002 January 31 10