CODEWITHSUNDEEP
bashsed
Attila H
Attila H

Reputation: 3606

How to modify an integer using Bash sed

I have an XML node like this:

<point type="2D" x="61" y="273" />

I wish to multiply x by 2 using Bash. I had tried the following:

echo '<rect key="frame" x="61" y="273" width="199" height="21"/>' | sed "s/x=\"\([[:digit:]]*\)\"/x=\"$((\1 * 2))\"/"

But it failed with:

syntax error: operand expected (error token is "\\1 * 2")

Any idea how to make this work?

Upvotes: 0

Views: 62

Answers (2)

anubhava
anubhava

Reputation: 784878

sed is not the the right tool for this. You can use this gnu awk command with a custom record separator:

awk -v RS='.*x="|".*' '!NF{ s=RT } NF{ print s $1*2 RT }' file
<point type="2D" x="122" y="273" />

However it is better to use a proper XML parser for thorough XML parsing.

Upvotes: 3

nlu
nlu

Reputation: 1963

This is quite easy to achieve with perl:

perl -p -e 's/x="([0-9]+)"/"x=\"".($1*2)."\""/e' input.xml

To replace directly, add -i like you would with sed.

Upvotes: 1

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