103 lines
4.1 KiB
Plaintext
103 lines
4.1 KiB
Plaintext
'\"
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'\" Copyright (c) 1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH history n "" Tcl "Tcl Built-In Commands"
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.so man.macros
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.BS
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'\" Note: do not modify the .SH NAME line immediately below!
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.SH NAME
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history \- Manipulate the history list
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.SH SYNOPSIS
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\fBhistory \fR?\fIoption\fR? ?\fIarg arg ...\fR?
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.BE
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.SH DESCRIPTION
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.PP
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The \fBhistory\fR command performs one of several operations related to
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recently-executed commands recorded in a history list. Each of
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these recorded commands is referred to as an
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.QW event .
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When specifying an event to the \fBhistory\fR command, the following
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forms may be used:
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.IP [1]
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A number: if positive, it refers to the event with
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that number (all events are numbered starting at 1). If the number
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is negative, it selects an event relative to the current event
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(\fB\-1\fR refers to the previous event, \fB\-2\fR to the one before that, and
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so on). Event \fB0\fR refers to the current event.
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.IP [2]
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A string: selects the most recent event that matches the string.
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An event is considered to match the string either if the string is
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the same as the first characters of the event, or if the string
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matches the event in the sense of the \fBstring match\fR command.
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.PP
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The \fBhistory\fR command can take any of the following forms:
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.TP
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\fBhistory\fR
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Same
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as \fBhistory info\fR, described below.
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.TP
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\fBhistory add\fI command \fR?\fBexec\fR?
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Adds the \fIcommand\fR argument to the history list as a new event. If
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\fBexec\fR is specified (or abbreviated) then the command is also
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executed and its result is returned. If \fBexec\fR is not specified
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then an empty string is returned as result.
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.TP
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\fBhistory change\fI newValue\fR ?\fIevent\fR?
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Replaces the value recorded for an event with \fInewValue\fR. \fIEvent\fR
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specifies the event to replace, and
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defaults to the \fIcurrent\fR event (not event \fB\-1\fR). This command
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is intended for use in commands that implement new forms of history
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substitution and wish to replace the current event (which invokes the
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substitution) with the command created through substitution. The return
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value is an empty string.
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.TP
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\fBhistory clear\fR
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Erase the history list. The current keep limit is retained.
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The history event numbers are reset.
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.TP
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\fBhistory event\fR ?\fIevent\fR?
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Returns the value of the event given by \fIevent\fR. \fIEvent\fR
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defaults to \fB\-1\fR.
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.TP
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\fBhistory info \fR?\fIcount\fR?
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Returns a formatted string (intended for humans to read) giving
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the event number and contents for each of the events in the history
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list except the current event. If \fIcount\fR is specified
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then only the most recent \fIcount\fR events are returned.
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.TP
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\fBhistory keep \fR?\fIcount\fR?
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This command may be used to change the size of the history list to
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\fIcount\fR events. Initially, 20 events are retained in the history
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list. If \fIcount\fR is not specified, the current keep limit is returned.
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.TP
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\fBhistory nextid\fR
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Returns the number of the next event to be recorded
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in the history list. It is useful for things like printing the
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event number in command-line prompts.
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.TP
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\fBhistory redo \fR?\fIevent\fR?
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Re-executes the command indicated by \fIevent\fR and returns its result.
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\fIEvent\fR defaults to \fB\-1\fR. This command results in history
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revision: see below for details.
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.SH "HISTORY REVISION"
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.PP
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Pre-8.0 Tcl had a complex history revision mechanism.
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The current mechanism is more limited, and the old
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history operations \fBsubstitute\fR and \fBwords\fR have been removed.
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(As a consolation, the \fBclear\fR operation was added.)
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.PP
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The history option \fBredo\fR results in much simpler
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.QW "history revision" .
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When this option is invoked then the most recent event
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is modified to eliminate the history command and replace it with
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the result of the history command.
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If you want to redo an event without modifying history, then use
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the \fBevent\fR operation to retrieve some event,
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and the \fBadd\fR operation to add it to history and execute it.
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.SH KEYWORDS
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event, history, record
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