Linux

This article will show you how to use a Heredoc (Here Document) in Bash/Shell scripts to work with multi-line text. Heredocs are most useful for accepting multi-line input- the user can enter a line of text, press enter, then enter the next line, and so on. It can also be used to define multi-line text in scripts. It can also send multiple commands into an interactive program – this will be shown in the examples later. The examples in this article will work in both … Read more

This article will show you some practical examples for using the printf command in the Bash/Shell on Linux. The printf command outputs text much like the echo command does – but it allows for more control over the output formatting. It’s a useful tool for generating your own formatted text output – especially if you need to embed variables in text, include newlines, align and format text, and even display converted values. printf Syntax The printf command has the following syntax: printf [-v var] format [arguments]… Note that: The -v option … Read more

This short tutorial will teach you to prompt the user for typed input from your Bash/Shell scripts. It’s easy to learn, easy to do, so read on! The read Command To read user input in shell scripts, use the aptly named read command. It has the following syntax: read OPTIONS VARIABLES Note that: The read command will read a line from standard input and split that input into fields Usually, standard input is the terminal with input from your keyboard, but you can also pipe or redirect input to the read command From the users perspective, they will … Read more

This article will show you how to run commands in the Linux (including Ubuntu) shell background. This is useful when working remotely via SSH. Say you’re connected remotely via SSH to a remote computer, and you want to execute a lengthy task. While the task is running, usually, you’d have to keep the connection open, with the terminal window open. However, this can be a hassle if you need to close the window to perform another task or if you have a spotty internet connection … Read more

The tr (translate) command in Linux reads text from standard input, performs some modification to the text, and then sends it to standard output. This article explains and shows why and how you might use it. tr Command Syntax Here’s the syntax you’ll need to use the command: tr OPTIONS SET1 [SET2] Note that: OPTIONS should be a list of options from the below table The characters in SET1 will be replaced with the characters in the corresponding position in SET2 These are optional – some of the OPTIONS are capable of performing translations, … Read more

This tutorial will teach you how to use the which command in Linux with some simple examples. The which command will tell you the path to the executable used by a command on the system if it exists. Why is this useful? Say you’ve got two copies of the MySQL executable installed on your system (installed via different means), and you want to know which one is actually in use so that the other can be removed – the which command can tell you which of the two is called when you execute MySQL on … Read more