1history(n)                   Tcl Built-In Commands                  history(n)
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NAME

8       history - Manipulate the history list
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SYNOPSIS

11       history ?option? ?arg arg ...?
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DESCRIPTION

15       The  history  command  performs  one  of  several operations related to
16       recently-executed commands recorded in a history list.  Each  of  these
17       recorded  commands  is  referred  to as an “event”.  When specifying an
18       event to the history command, the following forms may be used:
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20       [1]    A number:  if positive, it refers to the event with that  number
21              (all events are numbered starting at 1).  If the number is nega‐
22              tive, it selects an event relative  to  the  current  event  (-1
23              refers  to the previous event, -2 to the one before that, and so
24              on).  Event 0 refers to the current event.
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26       [2]    A string:  selects  the  most  recent  event  that  matches  the
27              string.   An  event  is considered to match the string either if
28              the string is the same as the first characters of the event,  or
29              if the string matches the event in the sense of the string match
30              command.
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32       The history command can take any of the following forms:
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34       history
35              Same as history info, described below.
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37       history add command ?exec?
38              Adds the command argument to the history list as  a  new  event.
39              If  exec  is specified (or abbreviated) then the command is also
40              executed and its result is returned.  If exec is  not  specified
41              then an empty string is returned as result.
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43       history change newValue ?event?
44              Replaces  the  value recorded for an event with newValue.  Event
45              specifies the event to replace,  and  defaults  to  the  current
46              event  (not event -1).  This command is intended for use in com‐
47              mands that implement new forms of history substitution and  wish
48              to  replace  the  current event (which invokes the substitution)
49              with the command created through substitution.  The return value
50              is an empty string.
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52       history clear
53              Erase  the  history  list.   The current keep limit is retained.
54              The history event numbers are reset.
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56       history event ?event?
57              Returns the value of the event given by event.   Event  defaults
58              to -1.
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60       history info ?count?
61              Returns  a formatted string (intended for humans to read) giving
62              the event number and contents for each of the events in the his‐
63              tory  list except the current event.  If count is specified then
64              only the most recent count events are returned.
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66       history keep ?count?
67              This command may be used to change the size of the history  list
68              to  count events.  Initially, 20 events are retained in the his‐
69              tory list.  If count is not specified, the current keep limit is
70              returned.
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72       history nextid
73              Returns  the number of the next event to be recorded in the his‐
74              tory list.  It is useful for things like printing the event num‐
75              ber in command-line prompts.
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77       history redo ?event?
78              Re-executes  the  command  indicated  by  event  and returns its
79              result.  Event defaults to -1.  This command results in  history
80              revision:  see below for details.
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HISTORY REVISION

83       Pre-8.0  Tcl  had  a  complex  history revision mechanism.  The current
84       mechanism is more limited, and the old  history  operations  substitute
85       and  words  have  been removed.  (As a consolation, the clear operation
86       was added.)
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88       The history option redo results in  much  simpler  “history  revision”.
89       When  this  option is invoked then the most recent event is modified to
90       eliminate the history command and replace it with  the  result  of  the
91       history  command.   If you want to redo an event without modifying his‐
92       tory, then use the event operation to retrieve some event, and the  add
93       operation to add it to history and execute it.
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KEYWORDS

96       event, history, record
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100Tcl                                                                 history(n)
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