You did not show your input document, but I assume it is the following, taken from the xmlstarlet documentation:
<xml>
<table>
<rec id="1">
<numField>123</numField>
<stringField>String Value</stringField>
</rec>
<rec id="2">
<numField>346</numField>
<stringField>Text Value</stringField>
</rec>
<rec id="3">
<numField>-23</numField>
<stringField>stringValue</stringField>
</rec>
</table>
</xml>
xmlstarlet modifies the file, but the result is sent to standard output, not saved in the original file. Use another option --inplace
to modify the file in place:
$ xml ed --inplace -u "/xml/table/rec[@id='3']/@id" -v 5 rec.xml
Then:
$ cat rec.xml
<?xml version="1.0"?>
<xml>
<table>
<rec id="1">
<numField>123</numField>
<stringField>String Value</stringField>
</rec>
<rec id="2">
<numField>346</numField>
<stringField>Text Value</stringField>
</rec>
<rec id="5">
<numField>-23</numField>
<stringField>stringValue</stringField>
</rec>
</table>
</xml>
By the way, this question seems to ask something very similar to this question.
EDIT: As suggested by @npostavs, this option is listed in the edit help:
$ xml edit --help
...
-L (or --inplace) - edit file inplace
...
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