SQL: powerful tricks with self-joins
If you are using SQL you know about the many types of joins, like inner join, left join, right, etc.. one particular powerful type of join…
cat sql-powerful-tricks-with-self-joins.md →$ ls -lh ./posts
// also on this box: ./practice, ./tools and ./games
SQL: return a random percentage of rows from a query
Assume you have the following task, you need to get a random percentage of records from a query, how do you do this? it might sound a bit…
cat sql-return-a-random-percentage-of-rows-from-a-query.md →
SQL: How to find the diff between two record sets
In this article, I will show you how to subtract one result set from another. The database I will use is SQLite which supports the EXCEPT…
cat sql-how-to-find-the-diff-between-two-record-sets.md →
How to troubleshoot crontab issues
Crontabs are super useful, you can schedule tasks to run recurrently at specific times or intervals, but there are common pitfalls that can…
cat how-to-troubleshoot-crontab-issues.md →
We are creating UUIDs with 3 different languages, which is faster?
Creating UUID is an effortless task with modern languages, all of them have libraries to develop them straightforwardly, but do they differ…
cat we-are-creating-uuids-with-3-different-languages-which-is-faster.md →
sslscan: Audit the SSL\TLS configuration of your web server
sslscan is a command line tool that gathers information about the SSL/TLS configuration of your web services which allows you to identify…
cat sslscan-audit-the-ssl-tls-configuration-of-your-web-server.md →
How to hide a file inside another file
Assume the following scenario! you are a spy and you want to hide your files! Since you are an expert spy you know that just making your…
cat how-to-hide-a-file-inside-another-file.md →
Python: How to swap variables without using a temporary variable
I guess everybody who has studied programming had an example of how to swap variables, all those examples because they were intended for…
cat python-how-to-swap-variables-without-using-a-temporary-variable.md →
Linux: How to find files with specific extensions and scp them to another host
One very common task of Sysadmins / Devops is to transfer files from one server to another, the most common way is to use scp, a tool that…
cat linux-how-to-find-files-with-specific-extensions-and-scp-them-to-another-host.md →
Linux: how to find files in a directory and compress them
One of the most common operations as a sysadmin / devops engineer is to find files in a directory and compress them. Let's see some handy…
cat linux-how-to-find-files-in-a-directory-and-compress-them.md →