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ActiveTcl User Guide |
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- NAME
- history - Manipulate the history list
- SYNOPSIS
- history ?option? ?arg arg ...?
- DESCRIPTION
- history
- history add
command ?exec?
- history change
newValue ?event?
- history
clear
- history event
?event?
- history info
?count?
- history keep
?count?
- history
nextid
- history redo
?event?
- HISTORY REVISION
- KEYWORDS
history - Manipulate the history list
history ?option? ?arg arg ...?
The history command performs one of several operations
related to recently-executed commands recorded in a history list.
Each of these recorded commands is referred to as an ``event''. When specifying an event to the
history command, the following forms may be used:
- [1]
- A number: if positive, it refers to the event with that number
(all events are numbered starting at 1). If the number is negative,
it selects an event relative to the current event (-1 refers
to the previous event, -2 to the one before that, and so
on). Event 0 refers to the current event.
- [2]
- A string: selects the most recent event that matches the
string. An event is considered to match the string either if the
string is the same as the first characters of the event, or if the
string matches the event in the sense of the string match command.
The history command can take any of the following
forms:
- history
- Same as history info, described below.
- history add command
?exec?
- Adds the command argument to the history list as a new
event. If exec is specified (or abbreviated) then the
command is also executed and its result is returned. If exec
isn't specified then an empty string is returned as result.
- history change newValue
?event?
- Replaces the value recorded for an event with newValue.
Event specifies the event to replace, and defaults to the
current event (not event -1). This command is
intended for use in commands that implement new forms of history
substitution and wish to replace the current event (which invokes
the substitution) with the command created through substitution.
The return value is an empty string.
- history clear
- Erase the history list. The current keep limit is retained. The
history event numbers are reset.
- history event ?event?
- Returns the value of the event given by event.
Event defaults to -1.
- history info ?count?
- Returns a formatted string (intended for humans to read) giving
the event number and contents for each of the events in the history
list except the current event. If count is specified then
only the most recent count events are returned.
- history keep ?count?
- This command may be used to change the size of the history list
to count events. Initially, 20 events are retained in the
history list. If count is not specified, the current keep
limit is returned.
- history nextid
- Returns the number of the next event to be recorded in the
history list. It is useful for things like printing the event
number in command-line prompts.
- history redo ?event?
- Re-executes the command indicated by event and returns
its result. Event defaults to -1. This command
results in history revision: see below for details.
Pre-8.0 Tcl had a complex history revision mechanism. The current
mechanism is more limited, and the old history operations
substitute and words have been removed. (As a
consolation, the clear operation was added.)
The history option redo results in much simpler ``history
revision''. When this option is invoked then the most recent event
is modified to eliminate the history command and replace it with
the result of the history command. If you want to redo an event
without modifying history, then use the event operation to retrieve some
event, and the add operation to add it to history and
execute it.
event, history, record
Copyright © 1993 The Regents of the University of California.
Copyright © 1994-1997 Sun Microsystems, Inc.
Copyright © 1995-1997 Roger E. Critchlow Jr.