Finding out the username by user id (uid) in Unix is not as common a task as determining the uid by a username, but if you need to do it – I'll show you how.
If you tried installing or upgrading Ubuntu recently, you probably noticed that all the storage devices are now using UUID – Universally Unique IDentifiers. I'm not claiming to know everything there is to know about UUIDs, but have become quite comfortable managing them lately, so hopefully this post will help you achieve the same.
What is a UUID exactly?
UUID is a Universally Unique IDentifier. It's a identification code given to each storage device you have on your system, aimed to help you uniquely identify each device no matter what.
Any Unix shell script longer than a line will most likely involve using variables. Variables are used to store temporary values to simply using them in various Unix commands of your script. The beauty of using variables is that they can be evaluated and set ones, but then reused as many times as you like without your shell interpreter having to re-evaluate them again.
Defining a variable in Unix shell
To specify a value for a variable, you need to decide on the variable name – can be any word or combination of English alphabet symbols and digits, and specify the value.
Showing your processes in a hierarchical list is very useful for confirming the relationship between every process running on your system. Today I'd like to show you how you can get tree-like processes lists using various commands.