history - Manipulate the history list
? ?arg arg ...
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:
- 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.
- 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.
command can take any of the following forms:
- 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 is not 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
- 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
- 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
- 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
have been removed. (As a consolation, the clear
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