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Asked: 2024-09-26T01:14:37+05:30 In:

What is the reason for linking the sh shell to dash in Ubuntu?

I’ve been diving deep into Ubuntu recently and came across something that’s had me scratching my head. So, I stumbled upon the fact that in Ubuntu, they’ve linked the sh shell to dash instead of bash. At first, it seems like just a simple technical choice, but I can’t help but wonder what’s at the heart of this decision. I mean, bash has been the go-to shell for many users and scripts for ages, right?

From what I’ve read, dash is supposed to be faster and more efficient, especially for running scripts. But is that really the only reason they decided to make this switch? I feel like there has to be more to it than just speed. What about compatibility? A lot of scripts out there are written in bash, so does that mean that if you run them in dash, you’re likely to run into issues?

And here’s another thing that’s puzzling me: when you’re using Ubuntu, if you’re used to typing bash commands, does switching to dash require you to learn new syntax or adjust how you think about shell scripting? I’ve heard that some functions in bash aren’t available in dash. Is that something that would catch a lot of beginners off guard?

I also wonder about the performance aspect. Sure, dash is faster for script execution, but does that speed have a noticeable impact in real-world usage for most users? I mean, most of the time, we’re not running scripts non-stop—at least I’m not. So, would the average Ubuntu user really notice a difference, or is this more of a backend optimization that mostly benefits developers?

I’d love to hear what others think about this. If you’ve experienced issues or advantages with the switch from bash to dash or if you have insights about how this impacts script writing or system performance, please share! I’m really curious to get different perspectives on this whole shell linking decision. It feels like a rabbit hole just waiting for someone to explore!

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    2 Answers



    1. Why Ubuntu Uses Dash Instead of Bash

      Why Does Ubuntu Use Dash as /bin/sh?

      So, you’re diving into Ubuntu and come across this sh linked to dash instead of bash thing. It’s super interesting! 😄

      Performance and Efficiency

      You’re spot on about dash being faster! It’s way lighter and can execute scripts quicker, which is especially helpful when a lot of scripts are run during boot or system updates. Think of it as the lightweight runner in a race—fast and efficient! But yeah, that does bring up questions like, “Is speed the only reason?”

      Script Compatibility

      As for compatibility, that’s a good point! While most simple scripts will run fine in dash, anything that uses bash-specific features (like arrays or certain built-in commands) might throw errors. So, if you’re diving into writing scripts, just remember that some of the cooler bash features won’t work in dash!

      Learning Curve

      Now about learning new syntax—good news is, if you’re just using the basic commands, you might not need to change much. But if you rely on those fancy bash functions, you might want to brush up on what works in dash. It could catch beginners off guard, for sure!

      Real-World Impact

      Regarding performance for regular users, unless you’re writing a lot of scripts or running them all the time, you probably won’t notice a huge difference in day-to-day tasks. It’s definitely more of a developer benefit or for the system to run smoother in the background, you know?

      In Closing

      Overall, it feels like Ubuntu’s decision to link sh to dash is mostly about making things faster and cleaner for the system. But it also has some implications for script writers. If you’re experimenting with scripting, just keep in mind the limitations of dash compared to bash, and maybe try dipping your toes into writing scripts in both shells. Happy exploring!



    2. Ubuntu’s decision to link the sh shell to dash instead of bash stems primarily from performance and efficiency considerations. Dash is designed to be lightweight and faster when executing scripts, which can be particularly beneficial for system boot processes and script-heavy environments. While bash offers a rich set of features and is widely used among users for interactive shells, it can introduce overhead that isn’t necessary for script execution. Consequently, many users might not notice this speed difference in their day-to-day interactions but it provides a substantial improvement for automated processes and server environments where script execution time can impact performance. Compatibility is indeed a concern when switching from bash to dash, as some bash features and extensions, such as arrays and certain read options, are not available in dash. For those relying on complex bash scripts, this could lead to potential issues.

      As for the learning curve, users accustomed to bash will generally not need to overhaul their entire approach to shell scripting when using dash for basic tasks. However, it’s important to be aware of the limitations in syntax and features that could confuse beginners who might be unaware of the nuances between the two shells. While the performance gains of dash are more evident in backend processes, end-users running typical interactive commands via bash might find the difference negligible. Overall, while script execution benefits from the switch to dash, the impact on an average user’s day-to-day command line experience is likely minimal. It ultimately encourages developers to write lighter, more portable scripts without relying on bash specific features that could limit script usability across different environments.


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