How do I add lines to every file inside a folder?
<p>I am trying to add license declaration to all files inside a folder. Is there any shortcuts / linux commands to do that? If this can be done to files of a specific extension that will be even better.</p>

<p>Edit: This was my final command based on @vimsha's answer:
<code>
find . -type f -name "*.js" -exec sh -c 'echo "/* @flow */\n$(cat $0)" &gt; $0' {} \;
</code></p>