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Accepted
Gerald Schneider
Asked: 2019-05-10 11:49:46 +0800 CST

grep exclude multiline pattern

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Searching for multiline patterns in files with grep is trivial. Inverting that pattern not so much.

Background: I want to create clean variable files without passwords so I can commit them into a repository.

Example of a variable file containing an encrypted password:

ansible_user: rick
ansible_become_password: !vault |
        $ANSIBLE_VAULT;1.1;AES256
        35623732646263636163383738353230626565383533626261313564383832643334363632383134
        3833316539376436333462303564636236646662376535300a356631346166626632333365353465
        30343138313363666434343938393464343861666234633434383037393230633333333364383835
        3962383339373731610a316362326239386539633638646331636633333330633231383730323634
        33653332353239353662366631373037653135303163663365633532643535663933
never: 'gonna,give,you,up'

Intended result:

ansible_user: rick
never: 'gonna,give,you,up'

I can easily match the lines containing the passwords with this command:

grep -Pz '.+\: !vault \|(\n\s+.+){2,}' host_vars/host.yml

The problem: The parameter -v, which usually inverts the result, doesn't work with -P

How can I create a copy of the variable files without the password lines?

ansible

2 Answers

  1. It's hackish because it wouldn't work in you have other multiline variables, but in this case:

    grep -v -e password -e '^\s'

    So it would just skip anything that starts with white space. If you want a more elegant solution I would use a command line program for dealing with yaml files and see if you can exclude values. Dealing with yaml files using the cli is covered in detail in other posts on this site: https://stackoverflow.com/questions/5014632/how-can-i-parse-a-yaml-file-from-a-linux-shell-script

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  2. Best Answer

    I got it working using pcregrep:

    pcregrep -vM "\!vault.+\n(\s{4,}.+\n){2,}" host_vars/host.yml

    But that requires to install pcregrep, which at least on ubuntu is not standard. Therefore I'm still open for better suggestions.

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