Mage::getSingleton('adminhtml/session')->addError($this->__('Failed to save.'));

Dumping with on-the-fly gzip and speed indicator*.

$ mysqldump -u root -p database | pv | gzip -c > database.sql.gz

Loading with on-the-fly gunzip and speed indicator*.

$ pv database.sql.gz | gunzip | mysql -u root -p database

* Package pv should be installed

<reference name="head">
   <block type="core/text" name="google.cdn.jquery">
      <action method="setText">
        <text>
           <![CDATA[<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script><script type="text/javascript">jQuery.noConflict();</script>]]>
        </text>
      </action>
   </block>
</reference>

tar -zcvf filename.tar.gz /path/to/dir
tar -zxvf filename.tar.gz -C /tmp

sudo diff -urN some/first/folder  some/second/folder > /path/to/patch/file/some_file.patch

rm -rf var/generation/
rm -rf pub/static/frontend/
rm -rf pub/static/_requirejs/frontend/
rm -rf var/view_preprocessed/
rm -rf var/cache/
rm -rf var/page_cache/
php bin/magento setup:upgrade
php bin/magento setup:static-content:deploy
php bin/magento cache:flush
sudo service varnish restart

mysqldump -u user -p dbname | gzip -c | cat > ~/backup/db-dev-$(date +%Y-%m-%d-%H.%M.%S).sql.gz