diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/history.3 | 687 |
1 files changed, 687 insertions, 0 deletions
diff --git a/doc/history.3 b/doc/history.3 new file mode 100644 index 0000000..df6cd37 --- /dev/null +++ b/doc/history.3 @@ -0,0 +1,687 @@ +.\" +.\" MAN PAGE COMMENTS to +.\" +.\" Chet Ramey +.\" Information Network Services +.\" Case Western Reserve University +.\" chet.ramey@case.edu +.\" +.\" Last Change: Fri Jul 17 09:43:01 EDT 2020 +.\" +.TH HISTORY 3 "2020 July 17" "GNU History 8.1" +.\" +.\" File Name macro. This used to be `.PN', for Path Name, +.\" but Sun doesn't seem to like that very much. +.\" +.de FN +\fI\|\\$1\|\fP +.. +.ds lp \fR\|(\fP +.ds rp \fR\|)\fP +.\" FnN return-value fun-name N arguments +.de Fn1 +\fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3\fP\\*(rp +.br +.. +.de Fn2 +.if t \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3,\|\\$4\fP\\*(rp +.if n \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3, \\$4\fP\\*(rp +.br +.. +.de Fn3 +.if t \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3,\|\\$4,\|\\$5\fP\|\\*(rp +.if n \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3, \\$4, \\$5\fP\\*(rp +.br +.. +.de Vb +\fI\\$1\fP \fB\\$2\fP +.br +.. +.SH NAME +history \- GNU History Library +.SH COPYRIGHT +.if t The GNU History Library is Copyright \(co 1989-2020 by the Free Software Foundation, Inc. +.if n The GNU History Library is Copyright (C) 1989-2020 by the Free Software Foundation, Inc. +.SH DESCRIPTION +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. +.PP +.SH "HISTORY EXPANSION" +The history library supports a history expansion feature that +is identical to the history expansion in +.BR bash. +This section describes what syntax features are available. +.PP +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 current input line, or +fix errors in previous commands quickly. +.PP +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 \fIevent\fP, +and the portions of that line that are acted upon are \fIwords\fP. +Various \fImodifiers\fP are available to manipulate the selected words. +The line is broken into words in the same fashion as \fBbash\fP +does when reading input, +so that several words that would otherwise be separated +are considered one word when surrounded by quotes (see the +description of \fBhistory_tokenize()\fP below). +History expansions are introduced by the appearance of the +history expansion character, which is \^\fB!\fP\^ by default. +Only backslash (\^\fB\e\fP\^) and single quotes can quote +the history expansion character. +.SS Event Designators +An event designator is a reference to a command line entry in the +history list. +Unless the reference is absolute, events are relative to the current +position in the history list. +.PP +.PD 0 +.TP +.B ! +Start a history substitution, except when followed by a +.BR blank , +newline, = or (. +.TP +.B !\fIn\fR +Refer to command line +.IR n . +.TP +.B !\-\fIn\fR +Refer to the current command minus +.IR n . +.TP +.B !! +Refer to the previous command. This is a synonym for `!\-1'. +.TP +.B !\fIstring\fR +Refer to the most recent command +preceding the current position in the history list +starting with +.IR string . +.TP +.B !?\fIstring\fR\fB[?]\fR +Refer to the most recent command +preceding the current position in the history list +containing +.IR string . +The trailing \fB?\fP may be omitted if +.I string +is followed immediately by a newline. +If \fIstring\fP is missing, the string from the most recent search is used; +it is an error if there is no previous search string. +.TP +.B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u +Quick substitution. Repeat the last command, replacing +.I string1 +with +.IR string2 . +Equivalent to +``!!:s\d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u'' +(see \fBModifiers\fP below). +.TP +.B !# +The entire command line typed so far. +.PD +.SS Word Designators +Word designators are used to select desired words from the event. +A +.B : +separates the event specification from the word designator. +It may be omitted if the word designator begins with a +.BR ^ , +.BR $ , +.BR * , +.BR \- , +or +.BR % . +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. +.PP +.PD 0 +.TP +.B 0 (zero) +The zeroth word. For the shell, this is the command +word. +.TP +.I n +The \fIn\fRth word. +.TP +.B ^ +The first argument. That is, word 1. +.TP +.B $ +The last word. This is usually the last argument, but will expand to the +zeroth word if there is only one word in the line. +.TP +.B % +The first word matched by the most recent `?\fIstring\fR?' search, +if the search string begins with a character that is part of a word. +.TP +.I x\fB\-\fPy +A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'. +.TP +.B * +All of the words but the zeroth. This is a synonym +for `\fI1\-$\fP'. It is not an error to use +.B * +if there is just one +word in the event; the empty string is returned in that case. +.TP +.B x* +Abbreviates \fIx\-$\fP. +.TP +.B x\- +Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word. +If \fBx\fP is missing, it defaults to 0. +.PD +.PP +If a word designator is supplied without an event specification, the +previous command is used as the event. +.SS Modifiers +After the optional word designator, there may appear a sequence of +one or more of the following modifiers, each preceded by a `:'. +These modify, or edit, the word or words selected from the history event. +.PP +.PD 0 +.PP +.TP +.B h +Remove a trailing file name component, leaving only the head. +.TP +.B t +Remove all leading file name components, leaving the tail. +.TP +.B r +Remove a trailing suffix of the form \fI.xxx\fP, leaving the +basename. +.TP +.B e +Remove all but the trailing suffix. +.TP +.B p +Print the new command but do not execute it. +.TP +.B q +Quote the substituted words, escaping further substitutions. +.TP +.B x +Quote the substituted words as with +.BR q , +but break into words at +.B blanks +and newlines. +The \fBq\fP and \fBx\fP modifiers are mutually exclusive; the last one +supplied is used. +.TP +.B s/\fIold\fP/\fInew\fP/ +Substitute +.I new +for the first occurrence of +.I old +in the event line. +Any character may be used as the delimiter in place of /. +The final delimiter is optional if it is the last character of the +event line. +The delimiter may be quoted in +.I old +and +.I new +with a single backslash. If & appears in +.IR new , +it is replaced by +.IR old . +A single backslash will quote the &. +If +.I old +is null, it is set to the last +.I old +substituted, or, if no previous history substitutions took place, +the last +.I string +in a +.B !?\fIstring\fR\fB[?]\fR +search. +If +.I new +is null, each matching +.I old +is deleted. +.TP +.B & +Repeat the previous substitution. +.TP +.B g +Cause changes to be applied over the entire event line. This is +used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR') +or `\fB:&\fP'. If used with +`\fB:s\fP', any delimiter can be used +in place of /, and the final delimiter is optional +if it is the last character of the event line. +An \fBa\fP may be used as a synonym for \fBg\fP. +.TP +.B G +Apply the following `\fBs\fP' or `\fB&\fP' modifier once to each word +in the event line. +.PD +.SH "PROGRAMMING WITH HISTORY FUNCTIONS" +This section describes how to use the History library in other programs. +.SS Introduction to History +A programmer using the History library has available functions +for remembering lines on a history list, associating 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 \fIexpansion\fP function +is available which provides for a consistent user interface across +different programs. +.PP +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 previous lines and using that text +in new commands. The basic history manipulation commands are +identical to +the history substitution provided by \fBbash\fP. +.PP +The programmer can also use the Readline library, which +includes some history manipulation by default, and has the added +advantage of command line editing. +.PP +Before declaring any functions using any functionality the History +library provides in other code, an application writer should include +the file +.FN <readline/history.h> +in any file that uses the +History library's features. It supplies extern declarations for all +of the library's public functions and variables, and declares all of +the public data structures. +.SS History Storage +The history list is an array of history entries. A history entry is +declared as follows: +.PP +.Vb "typedef void *" histdata_t; +.PP +.nf +typedef struct _hist_entry { + char *line; + char *timestamp; + histdata_t data; +} HIST_ENTRY; +.fi +.PP +The history list itself might therefore be declared as +.PP +.Vb "HIST_ENTRY **" the_history_list; +.PP +The state of the History library is encapsulated into a single structure: +.PP +.nf +/* + * 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; +.fi +.PP +If the flags member includes \fBHS_STIFLED\fP, the history has been +stifled. +.SH "History Functions" +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. +If the maximum number of history entries has been set using +\fBstifle_history()\fP, and the new number of history entries would exceed +that maximum, the oldest history entry is removed. + +.Fn1 void add_history_time "const char *string" +Change the time stamp associated with the most recent history entry to +\fIstring\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. + +.Fn1 "histdata_t" free_history_entry "HIST_ENTRY *histent" +Free the history entry \fIhistent\fP and any history library private +data associated with it. Returns the application-specific data +so the caller can dispose of it. + +.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 the caller can dispose of any +application-specific 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. +The history list will contain only \fImax\fP entries at a time. + +.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. +The range of valid values of \fIoffset\fP starts at \fBhistory_base\fP +and ends at \fBhistory_length\fP \- 1. +If there is no entry there, or if \fIoffset\fP is outside the valid +range, return a \fBNULL\fP pointer. + +.Fn1 "time_t" history_get_time "HIST_ENTRY *" +Return the time stamp associated with the history entry passed as the argument. + +.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" +If the current history offset refers to a valid history entry, +increment the current history offset. +If the possibly-incremented history offset refers to a valid history +entry, return a pointer to that entry; +otherwise, 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 occurred 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 int history_write_timestamps +If non-zero, timestamps are written to the history file, so they can be +preserved between sessions. The default value is 0, meaning that +timestamps are not saved. +The current timestamp format uses the value of \fIhistory_comment_char\fP +to delimit timestamp entries in the history file. If that variable does +not have a value (the default), timestamps will not be written. + +.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, double-quoted words are not scanned for the history expansion +character or the history comment 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 +bfox@gnu.org +.PP +Chet Ramey, Case Western Reserve University +.br +chet.ramey@case.edu +.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 chet.ramey@case.edu . |