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Justin
Asked: 2011-09-09 14:26:20 +0800 CST

How To Search authorized_keys For Public Key And Remove It

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Hello I am looking for assistance searching /root/.ssh/authorized_keys for a given public key (call it $pub_key) and removing it. Want to do this in bash script.

What's the best way to accomplish this?

linux bash

3 Answers

  1. Best Answer

    Would grep -v $pub_key /root/.ssh/authorized_keys > /tmp/authorized_keys.new work? You can compared to two files to verify the work. Given the long strings of random characters that comprise the keys, it's probably sufficient to do this using a substring of $pub_key.

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  2. Never forget the power of perl oneliners!

    $pub_key="AAAABCD"; perl -i "/$pub_key/ or print" /root/.ssh/authorized_keys

    That will perform an in-place edit and remove the offending key.

    Or, perhaps you have a really really long authorized_keys file and you want to process it in parallel with gnu parallel?

    pub_key="AAAABCD"; parallel -k "echo {} | grep -v $pub_key" </root/.ssh/authorized_keys

    the possibilities are endless.

    update: fixed typo that Ole pointed out. Thanks Ole!

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  3. I think I need to use sed, but can't figure out the syntax, here is what I have thus far: 

    sed -i '/$pub_key/ d' /root/.ssh/authorized_keys

    Remove the space before d, it will work as you expect:

    sed -i '/$pub_key/d' /root/.ssh/authorized_keys
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