history.3

这个是LINUX下的GDB调度工具的源码

This section describes the calling sequence for the various functions
exported by the GNU History library.
.SS Initializing History and State Management
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.

.Fn1 void using_history void
Begin a session in which the history functions might be used.  This
initializes the interactive variables.

.Fn1 "HISTORY_STATE *" history_get_history_state void
Return a structure describing the current state of the input history.

.Fn1 void history_set_history_state "HISTORY_STATE *state"
Set the state of the history list according to \fIstate\fP.

.SS History List Management

These functions manage individual entries on the history list, or set
parameters managing the list itself.

.Fn1 void add_history "const char *string"
Place \fIstring\fP at the end of the history list.  The associated data
field (if any) is set to \fBNULL\fP.

.Fn1 "HIST_ENTRY *" remove_history "int which"
Remove history entry at offset \fIwhich\fP from the history.  The
removed element is returned so you can free the line, data,
and containing structure.

.Fn3 "HIST_ENTRY *" replace_history_entry "int which" "const char *line" "histdata_t data"
Make the history entry at offset \fIwhich\fP have \fIline\fP and \fIdata\fP.
This returns the old entry so you can dispose of the data.  In the case
of an invalid \fIwhich\fP, a \fBNULL\fP pointer is returned.

.Fn1 void clear_history "void"
Clear the history list by deleting all the entries.

.Fn1 void stifle_history "int max"
Stifle the history list, remembering only the last \fImax\fP entries.

.Fn1 int unstifle_history "void"
Stop stifling the history.  This returns the previously-set
maximum number of history entries (as set by \fBstifle_history()\fP).
history was stifled.  The value is positive if the history was
stifled, negative if it wasn't.

.Fn1 int history_is_stifled "void"
Returns non-zero if the history is stifled, zero if it is not.

.SS Information About the History List

These functions return information about the entire history list or
individual list entries.

.Fn1 "HIST_ENTRY **" history_list "void"
Return a \fBNULL\fP terminated array of \fIHIST_ENTRY *\fP which is the
current input history.  Element 0 of this list is the beginning of time.
If there is no history, return \fBNULL\fP.

.Fn1 int where_history "void"
Returns the offset of the current history element.

.Fn1 "HIST_ENTRY *" current_history "void"
Return the history entry at the current position, as determined by
\fBwhere_history()\fP.  If there is no entry there, return a \fBNULL\fP
pointer.

.Fn1 "HIST_ENTRY *" history_get "int offset"
Return the history entry at position \fIoffset\fP, starting from
\fBhistory_base\fP.
If there is no entry there, or if \fIoffset\fP
is greater than the history length, return a \fBNULL\fP pointer.

.Fn1 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.

.SS Moving Around the History List

These functions allow the current index into the history list to be
set or changed.

.Fn1 int history_set_pos "int pos"
Set the current history offset to \fIpos\fP, an absolute index
into the list.
Returns 1 on success, 0 if \fIpos\fP is less than zero or greater
than the number of history entries.

.Fn1 "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 \fBNULL\fP pointer.

.Fn1 "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 \fBNULL\fP pointer.

.SS Searching the History List

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 history position.  The search may be \fIanchored\fP,
meaning that the string must match at the beginning of the history entry.

.Fn2 int history_search "const char *string" "int direction"
Search the history for \fIstring\fP, starting at the current history offset.
If \fIdirection\fP is less than 0, then the search is through
previous entries, otherwise through subsequent entries.
If \fIstring\fP 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
\fIstring\fP was found.  Otherwise, nothing is changed, and a -1 is
returned.

.Fn2 int history_search_prefix "const char *string" "int direction"
Search the history for \fIstring\fP, starting at the current history
offset.  The search is anchored: matching lines must begin with
\fIstring\fP.  If \fIdirection\fP is less than 0, then the search is
through previous entries, otherwise through subsequent entries.
If \fIstring\fP 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. 

.Fn3 int history_search_pos "const char *string" "int direction" "int pos"
Search for \fIstring\fP in the history list, starting at \fIpos\fP, an
absolute index into the list.  If \fIdirection\fP is negative, the search
proceeds backward from \fIpos\fP, otherwise forward.  Returns the absolute
index of the history element where \fIstring\fP was found, or -1 otherwise.

.SS Managing the History File
The History library can read the history from and write it to a file.
This section documents the functions for managing a history file.

.Fn1 int read_history "const char *filename"
Add the contents of \fIfilename\fP to the history list, a line at a time.
If \fIfilename\fP is \fBNULL\fP, then read from \fI~/.history\fP.
Returns 0 if successful, or \fBerrno\fP if not.

.Fn3 int read_history_range "const char *filename" "int from" "int to"
Read a range of lines from \fIfilename\fP, adding them to the history list.
Start reading at line \fIfrom\fP and end at \fIto\fP.
If \fIfrom\fP is zero, start at the beginning.  If \fIto\fP is less than
\fIfrom\fP, then read until the end of the file.  If \fIfilename\fP is
\fBNULL\fP, then read from \fI~/.history\fP.  Returns 0 if successful,
or \fBerrno\fP if not.

.Fn1 int write_history "const char *filename"
Write the current history to \fIfilename\fP, overwriting \fIfilename\fP
if necessary.
If \fIfilename\fP is \fBNULL\fP, then write the history list to \fI~/.history\fP.
Returns 0 on success, or \fBerrno\fP on a read or write error.


.Fn2 int append_history "int nelements" "const char *filename"
Append the last \fInelements\fP of the history list to \fIfilename\fP.
If \fIfilename\fP is \fBNULL\fP, then append to \fI~/.history\fP.
Returns 0 on success, or \fBerrno\fP on a read or write error.

.Fn2 int history_truncate_file "const char *filename" "int nlines"
Truncate the history file \fIfilename\fP, leaving only the last
\fInlines\fP lines.
If \fIfilename\fP is \fBNULL\fP, then \fI~/.history\fP is truncated.
Returns 0 on success, or \fBerrno\fP on failure.

.SS History Expansion

These functions implement history expansion.

.Fn2 int history_expand "char *string" "char **output"
Expand \fIstring\fP, placing the result into \fIoutput\fP, a pointer
to a string.  Returns:
.RS
.PD 0
.TP
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);
.TP
1
if expansions did take place;
.TP
-1
if there was an error in expansion;
.TP
2
if the returned line should be displayed, but not executed,
as with the \fB:p\fP modifier.
.PD
.RE
If an error ocurred in expansion, then \fIoutput\fP contains a descriptive
error message.

.Fn3 "char *" get_history_event "const char *string" "int *cindex" "int qchar"
Returns the text of the history event beginning at \fIstring\fP +
\fI*cindex\fP.  \fI*cindex\fP is modified to point to after the event
specifier.  At function entry, \fIcindex\fP points to the index into
\fIstring\fP where the history event specification begins.  \fIqchar\fP
is a character that is allowed to end the event specification in addition
to the ``normal'' terminating characters.

.Fn1 "char **" history_tokenize "const char *string"
Return an array of tokens parsed out of \fIstring\fP, much as the
shell might.
The tokens are split on the characters in the
\fBhistory_word_delimiters\fP variable,
and shell quoting conventions are obeyed.

.Fn3 "char *" history_arg_extract "int first" "int last" "const char *string"
Extract a string segment consisting of the \fIfirst\fP through \fIlast\fP
arguments present in \fIstring\fP.  Arguments are split using
\fBhistory_tokenize()\fP.

.SS History Variables

This section describes the externally-visible variables exported by
the GNU History Library.

.Vb int history_base
The logical offset of the first entry in the history list.

.Vb int history_length
The number of entries currently stored in the history list.

.Vb int history_max_entries
The maximum number of history entries.  This must be changed using
\fBstifle_history()\fP.

.Vb char history_expansion_char
The character that introduces a history event.  The default is \fB!\fP.
Setting this to 0 inhibits history expansion.

.Vb char history_subst_char
The character that invokes word substitution if found at the start of
a line.  The default is \fB^\fP.

.Vb char history_comment_char
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 history expansion for the remainder of the line.
This is disabled by default.

.Vb "char *" history_word_delimiters
The characters that separate tokens for \fBhistory_tokenize()\fP.
The default value is \fB"\ \et\en()<>;&|"\fP.

.Vb "char *" history_no_expand_chars
The list of characters which inhibit history expansion if found immediately
following \fBhistory_expansion_char\fP.  The default is space, tab, newline,
\fB\er\fP, and \fB=\fP.

.Vb "char *" history_search_delimiter_chars
The list of additional characters which can delimit a history search
string, in addition to space, tab, \fI:\fP and \fI?\fP in the case of
a substring search.  The default is empty.

.Vb int history_quotes_inhibit_expansion
If non-zero, single-quoted words are not scanned for the history expansion
character.  The default value is 0.

.Vb "rl_linebuf_func_t *" history_inhibit_expansion_function
This should be set to the address of a function that takes two arguments:
a \fBchar *\fP (\fIstring\fP)
and an \fBint\fP index into that string (\fIi\fP).
It should return a non-zero value if the history expansion starting at
\fIstring[i]\fP should not be performed; zero if the expansion should
be done.
It is intended for use by applications like \fBbash\fP that use the history
expansion character for additional purposes.
By default, this variable is set to \fBNULL\fP.
.SH FILES
.PD 0 
.TP
.FN ~/.history
Default filename for reading and writing saved history
.PD
.SH "SEE ALSO"
.PD 0
.TP
\fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey
.TP
\fIThe Gnu History Library\fP, Brian Fox and Chet Ramey
.TP
\fIbash\fP(1)
.TP
\fIreadline\fP(3)
.PD
.SH AUTHORS
Brian Fox, Free Software Foundation
.br
[e-mail]
.PP
Chet Ramey, Case Western Reserve University
.br
[e-mail]
.SH BUG REPORTS
If you find a bug in the
.B history
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
.B history
library that you have.
.PP
Once you have determined that a bug actually exists, mail a
bug report to \fIbug\-readline\fP@\fIgnu.org\fP.
If you have a fix, you are welcome to mail that
as well!  Suggestions and `philosophical' bug reports may be mailed
to \fPbug-readline\fP@\fIgnu.org\fP or posted to the Usenet
newsgroup
.BR gnu.bash.bug .
.PP
Comments and bug reports concerning
this manual page should be directed to
.IR [e-mail] .