Category: Linux

Mark Wilkinson hits us with some basic Bash output management:

If you have experience with PowerShell, some properties of Bash variables will feel familiar. In Bash, variables are denoted with a $ just like in PowerShell, but unlike PowerShell the $ is only needed when they are being referenced. When you are assigning a value to a variable, the $ is left off:

#!/bin/bash
set -e
set -u

my_var="World"

printf "Hello ${my_var}\n"

Above we assigned a value to my_var without using the $, but when we then referenced it in the printf statement, we had to use a $. We also enclosed the variable name in curly braces. This is not required in all cases, but it is a good idea to get in the habit of using them. In cases where you are using positional parameters above 9 (we’ll talk about this later) or you are using a variable in the middle of a string the braces are required, but there is no harm in adding them every time you use a variable in a string.

The basic syntax is pretty familiar to most programming languages, and there’s nothing scary about outputs, even when Mark starts getting into streams.

Mark Wilkinson has started a new series on Bash.  His first post is an introduction to the scripting language:

Bash (the Bourne Again Shell) was created in 1989 for the GNU Project as a free replacement for the Unix Bourne shell. Most modern Linux systems use Bash as their default command line shell, so if you have ever dropped to a command line on a Linux system, you have probably used Bash. Just like PowerShell, Bash is both a scripting language and a command shell/interpreter. So not only can you execute commands in an interactive shell session, but you can also write scripts that incorporate multiple commands.

Once you get your hands dirty with Bash you’ll notice a lot of features that were incorporated into PowerShell. Things like command substitution: $(Get-Date) were directly pulled from Bash $(date). Other features will look familiar as well, like the ability to pipe multiple commands together.

One thing you need to understand right away is that Bash is string based, not object based like PowerShell. This means you’ll find yourself doing a lot more string processing to get tasks done. Things like string splitting will be much more common. Bash does support objects, like arrays, but few if any commands output an array. As we go through this series you’ll see that this might not be as limiting as it sounds.

The best part about learning Bash is that you can then get into arguments about Bash vs ksh vs zsh.