Rdb: Ruby-Nachbau der MWC /rdb-Werkzeuge

man/replace.man

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+.TH replace "" "" "/rdb Command"
+.PC "Insert a record into a file at specified location"
+\fBreplace [\-a] [\-m[bhirs] \fItableorlist from to \fB[\fIxfrom xto\fB] < \fIintableorlist\fR
+.PP
+.II row^replace
+The command
+.B replace
+replaces the row at offsets
+.I from
+through
+.I to
+in
+.I tableorlist
+with the contents of
+.IR intableorlist .
+.B replace
+will not insert a record larger than
+.I to
+minus
+.IR from .
+It adds spaces to the
+.I last
+column of records within
+.I tableorlist
+that are smaller than the input record.
+.PP
+.I xfrom
+and
+.I xto
+give the beginning and end of the offsets of the index entry within
+.IR tableorlist 's
+associated fast-access table, should there be one.
+.PP
+To obtain painlessly the offsets of the record and its index entry, use
+the command
+.BR seek .
+This is demonstrated in the following example.
+.PP
+The command
+.B update
+remembers the location and size of the record it takes out of a file
+and passes it to
+.B replace
+so that only a correctly sized file goes back into that file.
+.SH Options
+.B replace
+recognizes the following options:
+.IP \fB\-a\fR
+Do not append the record in
+.I intableorlist
+to the end of
+.IR tableorlist .
+The default to append if the record is too big
+to fit back into the location from which it was taken.
+This option allows you to prevent appending.
+If you want a binary file to stay
+sorted, you will either have to resort it or not allow appending.
+.IP \fB\-m[bhirs]\fR
+Fast access methods.
+See the manual page for
+.B index
+for a description of what each of these options means.
+.SH Example
+If table
+.B recordtable
+contains one record, you use can insert that record into table
+.B bigfile
+with the following command:
+.DM
+	replace bigfile 1421 1487 0 8 < recordtable
+.DE
+.PP
+Note that the contents of
+.B recordtable
+replace rows 1421 through 1487 within
+.BR bigfile .
+.PP
+For the second example, consider again table
+.BR inventory ,
+as follows:
+.DM
+Item    Amount  Cost    Value   Description   
+----    ------  ----    -----   --------------
+   1         3    50      150   rubber gloves
+   2       100     5      500   test tubes
+   3         5    80      400   clamps
+   4        23    19      437   plates
+   5        99    24     2376   cleaning cloth
+   6        89   147    13083   bunsen burners
+   7         5   175      875   scales
+.DE
+.PP
+First, let's use the command
+.B seek
+to extract a record, and save its offset in the shell variable
+.BR LOCATION :
+.DM
+	LOCATION=`echo 5 | seek -mr -o tmpfile inventory Item`
+.DE
+.PP
+.B $LOCATION
+is initialized to the following
+.DM
+	207 245 54 62
+.DE
+.PP
+and
+.B tmpfile
+contains the following:
+.DM
+Item    Amount  Cost    Value   Description   
+----    ------  ----    -----   --------------
+   5        99    24     2376   cleaning cloth
+.DE
+.PP
+Here we use the record fast-access method.
+.PP
+Now let's
+change 99 to 199 within
+.BR tmpfile ,
+so we can see a change:
+.DM
+Item    Amount  Cost    Value   Description   
+----    ------  ----    -----   --------------
+   5       199    24     2376   cleaning cloth
+.DE
+.PP
+Now we can replace the edited record in
+.BR inventory :
+.DM
+	replace -mr inventory $LOCATION < tmpfile
+.DE
+.PP
+.B inventory
+now appears as follows:
+.DM
+Item    Amount  Cost    Value   Description   
+----    ------  ----    -----   --------------
+   1         3    50      150   rubber gloves
+   2       100     5      500   test tubes
+   3         5    80      400   clamps
+   4        23    19      437   plates
+   5       199    24     2376   cleaning cloth
+   6        89   147    13083   bunsen burners
+   7         5   175      875   scales
+.DE
+.PP
+You can see that row 5 has been updated, because it now has
+199 in it.
+.SH "See Also"
+.B
+seek,
+update
+.R