On 6/17/20 2:36 PM, David Rosenstrauch wrote:

On 6/17/20 2:18 PM, Piscium via arch-general wrote:

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Today I set dash as my default shell [1] on two PCs. We will see if I get into trouble.

This question was asked years ago but maybe good to ask again. Could dash be made the default shell in Arch?

Couldn't you just set it as the default for your user using chsh?

This isn't about using it as a login shell. Describing this as "my default shell" is a very bad description. This is actually about setting dash as the system /bin/sh implementation. -- Eli Schwartz Bug Wrangler and Trusted User

On Wed, 17 Jun 2020 at 20:37, David Rosenstrauch wrote:

On 6/17/20 2:18 PM, Piscium via arch-general wrote:

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Today I set dash as my default shell [1] on two PCs. We will see if I get into trouble.

This question was asked years ago but maybe good to ask again. Could dash be made the default shell in Arch?

Couldn't you just set it as the default for your user using chsh?

I don't think many people will want to use dash as interactive shell. It's more about running shell scripts with a #!/bin/sh shebang. It is still possible to do that system wide of course, with a symlink in /usr/local/bin . The question whether it makes sense as default /bin/sh on Arch Linux remains valid though. I personally would be positive towards that change. -- Maarten

On 6/17/20 3:05 PM, NTS wrote:

On 17 Jun 2020 8:36 p.m., "David Rosenstrauch" wrote:

On 6/17/20 2:18 PM, Piscium via arch-general wrote:

...

Today I set dash as my default shell [1] on two PCs. We will see if I get into trouble.

This question was asked years ago but maybe good to ask again. Could dash be made the default shell in Arch?

Couldn't you just set it as the default for your user using chsh?

Yes, that would probably more safe. Also, you could have a user "doot" or whatever name with user ID 0 and shell /bin/dash to log in as a sys admin with dash.

Alternatively when you "su" interactively you could instead do "sudo dash".

Used to do the same (new user with ID 0 I mean) under Solaris and it worked flawlessly.

It would be extremely safe because it wouldn't do anything, not even what the original poster wanted. It's completely unrelated to anything whatsoever. -- Eli Schwartz Bug Wrangler and Trusted User

On June 17, 2020 7:06:01 PM UTC, "Jack L. Frost" wrote:

On Wed, Jun 17, 2020 at 07:18:33PM +0100, Piscium via arch-general wrote:

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What do you think?

I'm not sure how much utility is in doing this

Pretty much this, to be honest. I don't really see the point of changing everyone's /bin/sh for one person's personal preference when there isn't really any point in doing so to begin with.

On June 17, 2020 7:27:29 PM UTC, Piscium via arch-general wrote:

On Wed, 17 Jun 2020 at 20:19, Kusoneko wrote:

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Pretty much this, to be honest. I don't really see the point of changing everyone's /bin/sh for one person's personal preference when there isn't really any point in doing so to begin with.

The reasons Ubuntu switched in 2006 and Debian in 2011 were speed, less bugs and more security. A simple benchmark I ran with several shells using konsole (which is one of the fastest terminals according to my simple benchmarks):

time ls -R /

• dash 8.45 • zsh 8.53 (1 % bigger) • bash 17.1 • fish 19.55

Times are in seconds, on my desktop that has a spinning drive. The first time it takes longer as the system caches stuff so the times above are after running a few times. I read that in some benchmarks dash is up to 4 times faster than bash.

Sure. I personally don't really have a dog in this fight, as I don't really do shell scripting and use zsh as my login shell in most cases, and bash otherwise, but someone has to play devil's advocate and point out the cost of changing something that is this widely establish across so many distros. Of course, as most things are made with Ubuntu as a baseline because it is supposedly the most user-friendly, I'd bet the issue I pointed out isn't widespread, but it is likely still there and needs to be pointed out.

Another proper consideration is continuity of development. If a death causes a shell to become abandonware as a result of a developer failing to arrange for another to take the project on updates if they happen at all will take some time. On Wed, 17 Jun 2020, Piscium via arch-general wrote:

Date: Wed, 17 Jun 2020 15:27:29 From: Piscium via arch-general To: General Discussion about Arch Linux Cc: Piscium Subject: Re: [arch-general] dash as default shell?

On Wed, 17 Jun 2020 at 20:19, Kusoneko wrote:

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Pretty much this, to be honest. I don't really see the point of changing everyone's /bin/sh for one person's personal preference when there isn't really any point in doing so to begin with.

The reasons Ubuntu switched in 2006 and Debian in 2011 were speed, less bugs and more security. A simple benchmark I ran with several shells using konsole (which is one of the fastest terminals according to my simple benchmarks):

time ls -R /

? dash 8.45 ? zsh 8.53 (1 % bigger) ? bash 17.1 ? fish 19.55

Times are in seconds, on my desktop that has a spinning drive. The first time it takes longer as the system caches stuff so the times above are after running a few times. I read that in some benchmarks dash is up to 4 times faster than bash.

--

On Wed, 17 Jun 2020 19:18:59 +0000, Kusoneko wrote:

I don't really see the point of changing everyone's /bin/sh for one person's personal preference when there isn't really any point in doing so to begin with.

See OP's first post:

I did some simple benchmarks and dash is much faster than bash, moreover being far smaller there is less chance of bugs.

-- Merlin Büge

On June 17, 2020 7:35:27 PM UTC, Eli Schwartz via arch-general wrote:

On 6/17/20 3:18 PM, Kusoneko wrote:

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On June 17, 2020 7:06:01 PM UTC, "Jack L. Frost" wrote:

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On Wed, Jun 17, 2020 at 07:18:33PM +0100, Piscium via arch-general wrote:

...

What do you think?

I'm not sure how much utility is in doing this

Pretty much this, to be honest. I don't really see the point of changing everyone's /bin/sh for one person's personal preference when there isn't really any point in doing so to begin with.

Completely free, no cost speed improvements have no utility? Reread the original post.

-- Eli Schwartz Bug Wrangler and Trusted User

It has the cost that everyone who uses scripts that use bashisms will inevitably have issues, furthermore, considering Arch only supports x86_64, I've yet to see systems under that architecture have low amounts of memory and 6MB of disk storage is incredibly small. The real question here is "Is it worth forcing people to remove bashisms or specify that the script is meant for bash in their scripts (whichever ones don't do so already) for a speed improvement on a shell scripts that work with dash?" Note that some upstreams will likely not care, and maintainers will have to patch the scripts manually in that case.

On 6/17/20 3:54 PM, Kusoneko wrote:

It has the cost that everyone who uses scripts that use bashisms will inevitably have issues, furthermore, considering Arch only supports x86_64, I've yet to see systems under that architecture have low amounts of memory and 6MB of disk storage is incredibly small. The real question here is "Is it worth forcing people to remove bashisms or specify that the script is meant for bash in their scripts (whichever ones don't do so already) for a speed improvement on a shell scripts that work with dash?" Note that some upstreams will likely not care, and maintainers will have to patch the scripts manually in that case.

Debian/Ubuntu has extensive prior art in this matter. It was very important and resulted in very noticeable speed improvements on x86_64 systems with lots of memory and disk storage, because pid 1 used to be shellscripts and doing it in bash is slow and gets even slower the more you fork new scripts. :) Also Linux isn't everything :) and there are plenty of systems where bash is not installed by default. e.g. the *BSDs. Also also, bash is not installed on systems such as alpine linux. So any script assuming /bin/sh is bash, is broken on lots of systems. ... This is not actually a problem, I've used dash as my /bin/sh for years and haven't once encountered a broken script. -- Eli Schwartz Bug Wrangler and Trusted User

On 6/17/20 15:58, brent s. wrote:

This is false. Or at the least, grievously inaccurate.

To clarify: This is less-so aimed at OP; the only issue there was a poor choice of words and explaining the suggested switch. The previous post was aimed moreso at those that do not understand there are two shells: one the system uses in scripts (usually init scripts, but more on that in a moment) vs. one the user uses, the interactive shell (the one you run commands from). /bin/sh should be fully POSIX-compatible, /bin/bash has extra features that users would find useful (such as various completion functions, etc.) dash is written to be POSIX-compliant, but no more. Now, to init- because Arch uses systemd (and, yes, now Debian and Ubuntu), one must wonder what benefit, if any, this actually serves. systemd invokes the command directly, it does not spawn a shell to run an init script like sysvinit, upstart, openrc, etc. This is, primarily, the purpose of the system shell. I don't really see much of a benefit to it being that Arch uses systemd. Granted, it probably wouldn't harm much either given the purpose of the system shell, and probably why those who have already changed it haven't seen any noticeable effects. It just seems like an unnecessary change. -- brent saner https://square-r00t.net/ GPG info: https://square-r00t.net/gpg-info

On Wed, Jun 17, 2020 at 11:17:08PM +0100, Piscium via arch-general wrote:

But switching to dash would also be about security, as less code means less bugs [5].

Usage of a more concise, powerful and clean shell language is much more suitable as a point when bringing forth an argument of there being less bugs. I'd say that the amount of bugs in the underlying implementation of a shell almost does matter nothing when compared to the horrors of hacked-together shell scripts that try to be as "basic" as possible, trying to be as "compatible" as possible with anything, exchanging cleanliness and expressiveness for horrible Debian init script-style code. Saving a pseudo-array into a string just to manually reconstruct the pseudo-list when the occasion arises to access a specific element is just one example of what awaits people who ignore the benefits of Bash arrays when they could have had them just by using a different shebang. And nearly everybody who has to write this quickly will do it wrong.

On 18/06/2020 18.22, Eli Schwartz via arch-general wrote:

On 6/18/20 12:08 PM, lists@2ion.de wrote:

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On Wed, Jun 17, 2020 at 11:17:08PM +0100, Piscium via arch-general wrote:

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But switching to dash would also be about security, as less code means less bugs [5].

Usage of a more concise, powerful and clean shell language is much more suitable as a point when bringing forth an argument of there being less bugs.

I'd say that the amount of bugs in the underlying implementation of a shell almost does matter nothing when compared to the horrors of hacked-together shell scripts that try to be as "basic" as possible, trying to be as "compatible" as possible with anything, exchanging cleanliness and expressiveness for horrible Debian init script-style code.

Saving a pseudo-array into a string just to manually reconstruct the pseudo-list when the occasion arises to access a specific element is just one example of what awaits people who ignore the benefits of Bash arrays when they could have had them just by using a different shebang.

Why does this have anything to do with switching /bin/sh? Scripts which do not "ignore the benefits of bash arrays when they could have had them just by using a different shebang", would not be affected by such a change as they do not, in fact, use a different shebang.

Meanwhile, scripts which use bashisms but a /bin/sh shebang are broken even if /bin/sh is a symlink to bash. Bash disables some, but not all, features of bash if it is invoked in POSIX mode, such as via a symlink named /bin/sh -- so, you do not even get the benefits of bash, and never have, if you used /bin/sh as your shebang.

This is a valid argument.

...

And nearly everybody who has to write this quickly will do it wrong.

And yet, some do not. Some write elegant, simple POSIX sh scripts which do it right. For example, people often forget that pipelines and functions are an option, and sometimes a much faster and better option than global state variables.

And most people who are writing /bin/bash scripts are *also* doing it wrong because they don't really know what they are doing. Just saying. :p

This is an argument from the Perfect/Robot programmer and is utterly false. We should just collectively face the truth that shell is not a good way to program anything non-trivial. :D Regards,

On 6/18/20 12:11 AM, David C. Rankin wrote:

On 06/17/2020 01:18 PM, Piscium via arch-general wrote:

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Today I set dash as my default shell [1] on two PCs. We will see if I get into trouble.

This question was asked years ago but maybe good to ask again. Could dash be made the default shell in Arch?

Please NO. Bash has been the default, and while there is nothing wrong with a Bourne-again (or Debian Almquist) type shell, it would break more than a decade of setups...

If you want Dash, make the change after install.

You pulled this assertion out of thin air, do you have any proof that it "breaks more than a decade of setups"? Note that as has already been pointed out, any setup which it breaks is inherently flawed, and in addition was broken on Debian, the most popular linux distribution by sheer numbers, as well as most non-Linux forms of Unix. It's actually in practice very unlikely that this will break anyone's setup. Also if you really think Arch Linux is afraid to break people's setups, I suggest you reread https://www.archlinux.org/news/python-is-now-python-3/ -- Eli Schwartz Bug Wrangler and Trusted User

On 18/06/2020 06.33, Eli Schwartz via arch-general wrote:

On 6/18/20 12:11 AM, David C. Rankin wrote:

...

On 06/17/2020 01:18 PM, Piscium via arch-general wrote:

...

Today I set dash as my default shell [1] on two PCs. We will see if I get into trouble.

This question was asked years ago but maybe good to ask again. Could dash be made the default shell in Arch?

Please NO. Bash has been the default, and while there is nothing wrong with a Bourne-again (or Debian Almquist) type shell, it would break more than a decade of setups...

If you want Dash, make the change after install.

You pulled this assertion out of thin air, do you have any proof that it "breaks more than a decade of setups"?

OP is the one making an assertion, so the burden of proof is on them. That said... I suspect most the system-wide breakage that would have been expected would be due to init scripts and systemd ameliorates that to a large degree.

Note that as has already been pointed out, any setup which it breaks is inherently flawed, and in addition was broken on Debian, the most popular linux distribution by sheer numbers, as well as most non-Linux forms of Unix.

Inherent flaws in a setup doesn't mean that shit doesn't break. Ideally, yes, there would be no flaws, but this is the real world. Doubtless, we all try to strive towards perfection, but there is no such thing in practice.

It's actually in practice very unlikely that this will break anyone's setup.

Also if you really think Arch Linux is afraid to break people's setups, I suggest you reread https://www.archlinux.org/news/python-is-now-python-3/

In practice, I agree that it probably won't break much, but your arguments largely don't hold water. Regards and FWIW,

On 19/06/2020 00.18, Eli Schwartz via arch-general wrote:

I've provided rationale why I don't believe it will break much, you *agree* with me, and yet you say my arguments don't hold water?

Heh, I'm too tired to get into a detailed debate, but it's very possible to be right for the wrong reasons! :) Regards,

On 6/18/20 7:15 PM, Chris Billington via arch-general wrote:

I haven't seen this mentioned yet which makes me wonder if I've misunderstood, but isn't it already the case that bash runs in a posix-compatible mode if executed as /bin/sh?

I remember a bug a while back [1] that broke graphical login because flatpak used a bashism in an X startup script. Does this not imply that any bashisms executed with /bin/sh would already be causing breakage today on Arch Linux?

[1] https://bugs.archlinux.org/task/61420#comment176360

Yep -- as I said earlier in the thread:

Meanwhile, scripts which use bashisms but a /bin/sh shebang are broken even if /bin/sh is a symlink to bash. Bash disables some, but not all, features of bash if it is invoked in POSIX mode, such as via a symlink named /bin/sh -- so, you do not even get the benefits of bash, and never have, if you used /bin/sh as your shebang.

-- Eli Schwartz Bug Wrangler and Trusted User