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I'm genuinely curious, why? If you're writing generic scripts designed to run across multiple platforms then fine, but in the context of Google (or most other c

I'm genuinely curious, why? If you're writing generic scripts designed to run across multiple platforms then fine, but in the context of Google (or most other companies) they'll have a standard set of tooling available on all their machines, which presumably includes Bash if they're making that statement. What about POSIX shell makes it superior for scripting?

JepZ 8y ago
Maybe one day there will be another cool and dominating shell. That shell is more likely to be POSIX compliant than bash compliant.
- deleted 8y ago
  [deleted]
- oblio 8y ago
  All the cool new shells I've seen are either completely POSIX incompatible (powershell, xonsh, etc.) or they try to be bash supersets (zsh, osh, etc.). Bash is a de facto modern standard. The only new purely POSIX shells I know are for embedded stuff (dash) and that space is neither fast moving nor in dire need of a better shell, since most modern shell features target interactive use. Or they make coding easier and/or safer, in which case we're back to point 1, with the POSIX incompatibility.
  - JepZ 8y ago
    Maybe the missing POSIX compatibility is the reason why they haven't replaced bash yet.
    - oblio 8y ago
      Nothing will replace bash within my lifetime. Zsh didn't even though it was superior for over a decade. Heck, Microsoft barely managed to supplant cmd 1-2 years ago, and that's in a non-standard, proprietary environment by what is arguably the biggest commercial platform maker in the world.
Sir_Cmpwn 8y ago
Google also makes it difficult to compile Chromium on platforms where /usr/bin/python is python 3, because their shebangs are: #!/usr/bin/env python Rather than the more portable: #!/usr/bin/env python3 Notably this causes problems for people on Arch Linux, and in the near future, Fedora. This post is presented as a style guide that others should adopt. Google may have bash ubiquiotously available internally, but their approach should not be taken as a model for others. Google's approach has caused real problems for their software's portability in exchange for dubious value-adds. >What about POSIX shell makes it superior for scripting? To address this specifically, I have written a blog article on the subject: https://drewdevault.com/2018/02/05/Introduction-to-POSIX-shell.html https://drewdevault.com/2018/02/05/Introduction-to-POSIX-she... The main points are: - bash is far from as ubiquitous as some people seem to think it is - sh is formally standardized and has multiple competing implementations, whereas bash is defined by its implementation and there is only one - sh is perfectly competent and easy to target, bash's value add is questionable - By the time you need the things bash offers you might as well not use a shell script at all
- marcoperaza 8y ago
  Competing implementations sounds like a potential downside to me. That’s just more possible configurations where a bug could be hiding. Even if you use standard posix shell, you’d be wise to target a single implementation and stick to it.
  - Sir_Cmpwn 8y ago
    So you think that competition between gcc and clang is harmful to the C and C++ ecosystems? If you find bugs in an implementation of POSIX sh, you should report it to that implementation. Multiple competing implementations is a sign of a good standard, it proves the standard's correctness and demonstrates its maturity. There is no standard to hold bash to. Any strange behavior of it might be decided as by design and kept forever (and replicated by anything which tries to be bash compatible) or it could be determined to be a bug and, when fixed, break the scripts which worked around it or depended on it. There's no way to know how this is going to shake out because there is no objective specification for the language. At least when there's a bug in one of these competing sh implementations that you're so worried about, it's objectively a bug and can be fixed.
simias 8y ago
I don't feel as strongly about it as Sir_Cmpwn does but I agree with him. The logic goes something like: you should only use shell scripts for small scripts and not complex applications. Ergo the added functionality of bash scripts should not be necessary anyway and might actually lead you to believe that it's a proper programming language. Or to put it the other way around: if you find yourself writing a POSIX shell script and find that you'd like to use more advanced features then one of two things can happen: - You need portability to SunOS 4, so you suck it up and keep hacking your script because bash is not an option anyway; - You don't need portability, so then why not use a proper programming language like python, perl or ruby rather than upgrading from crappy sh to slightly-less-crappy bash?
- avar 8y ago
  This logic is insane. This is like a company that mainly does C++ or Java saying that if you must use a scripting language it must be Tcl, not Perl or Python, least you get too comfortable with it. If you want a policy against shellscripts growing out of hand have a policy against that, not that you must use the lowest common denominator even though you have Bash everywhere. And I'm saying this as someone who almost exclusively writes POSIX sh for portability reasons, but my software isn't meant to target just Google's infra.
  - simias 8y ago
    I think it would be perfectly sane for a company to dictate which scripting language their environment will support. Shell scripts are a bit different though because if you write a large enough software system on a unix-like OS you'll probably want to write a few shell scripts here and there to glue things together, so forbidding them completely would be a bit silly and counterproductive. Saying "avoid shell scripts, if you really have to write one it must be simple and use POSIX sh" is not particularly insane to me. But anyway my argument was more about my opinion about a developer talking for myself, not a company style guide. Life's too short to learn two shell dialects so I can either learn POSIX which will work basically everywhere and will let me write any simple script just fine or write Bash whose added complexity I probably won't need or even want. The fact that I'm an embedded dev probably biases my view though, I generally target environments where bash isn't an option anyway.
nurettin 8y ago
Probably because he can't use bash code in his BusyBox based router
- pas 8y ago
  And what's the magically amazing script that anyone would like to run on routers and AIXes alike, that it has to be POSIX portable? :)

JepZ 8y ago

Maybe one day there will be another cool and dominating shell. That shell is more likely to be POSIX compliant than bash compliant.

deleted 8y ago
[deleted]
oblio 8y ago
All the cool new shells I've seen are either completely POSIX incompatible (powershell, xonsh, etc.) or they try to be bash supersets (zsh, osh, etc.). Bash is a de facto modern standard. The only new purely POSIX shells I know are for embedded stuff (dash) and that space is neither fast moving nor in dire need of a better shell, since most modern shell features target interactive use. Or they make coding easier and/or safer, in which case we're back to point 1, with the POSIX incompatibility.
- JepZ 8y ago
  Maybe the missing POSIX compatibility is the reason why they haven't replaced bash yet.
  - oblio 8y ago
    Nothing will replace bash within my lifetime. Zsh didn't even though it was superior for over a decade. Heck, Microsoft barely managed to supplant cmd 1-2 years ago, and that's in a non-standard, proprietary environment by what is arguably the biggest commercial platform maker in the world.

Sir_Cmpwn 8y ago

Google also makes it difficult to compile Chromium on platforms where /usr/bin/python is python 3, because their shebangs are: #!/usr/bin/env python Rather than the more portable: #!/usr/bin/env python3 Notably this causes problems for people on Arch Linux, and in the near future, Fedora. This post is presented as a style guide that others should adopt. Google may have bash ubiquiotously available internally, but their approach should not be taken as a model for others. Google's approach has caused real problems for their software's portability in exchange for dubious value-adds. >What about POSIX shell makes it superior for scripting? To address this specifically, I have written a blog article on the subject: https://drewdevault.com/2018/02/05/Introduction-to-POSIX-shell.html https://drewdevault.com/2018/02/05/Introduction-to-POSIX-she... The main points are: - bash is far from as ubiquitous as some people seem to think it is - sh is formally standardized and has multiple competing implementations, whereas bash is defined by its implementation and there is only one - sh is perfectly competent and easy to target, bash's value add is questionable - By the time you need the things bash offers you might as well not use a shell script at all

marcoperaza 8y ago
Competing implementations sounds like a potential downside to me. That’s just more possible configurations where a bug could be hiding. Even if you use standard posix shell, you’d be wise to target a single implementation and stick to it.
- Sir_Cmpwn 8y ago
  So you think that competition between gcc and clang is harmful to the C and C++ ecosystems? If you find bugs in an implementation of POSIX sh, you should report it to that implementation. Multiple competing implementations is a sign of a good standard, it proves the standard's correctness and demonstrates its maturity. There is no standard to hold bash to. Any strange behavior of it might be decided as by design and kept forever (and replicated by anything which tries to be bash compatible) or it could be determined to be a bug and, when fixed, break the scripts which worked around it or depended on it. There's no way to know how this is going to shake out because there is no objective specification for the language. At least when there's a bug in one of these competing sh implementations that you're so worried about, it's objectively a bug and can be fixed.

simias 8y ago

I don't feel as strongly about it as Sir_Cmpwn does but I agree with him. The logic goes something like: you should only use shell scripts for small scripts and not complex applications. Ergo the added functionality of bash scripts should not be necessary anyway and might actually lead you to believe that it's a proper programming language. Or to put it the other way around: if you find yourself writing a POSIX shell script and find that you'd like to use more advanced features then one of two things can happen: - You need portability to SunOS 4, so you suck it up and keep hacking your script because bash is not an option anyway; - You don't need portability, so then why not use a proper programming language like python, perl or ruby rather than upgrading from crappy sh to slightly-less-crappy bash?

avar 8y ago
This logic is insane. This is like a company that mainly does C++ or Java saying that if you must use a scripting language it must be Tcl, not Perl or Python, least you get too comfortable with it. If you want a policy against shellscripts growing out of hand have a policy against that, not that you must use the lowest common denominator even though you have Bash everywhere. And I'm saying this as someone who almost exclusively writes POSIX sh for portability reasons, but my software isn't meant to target just Google's infra.
- simias 8y ago
  I think it would be perfectly sane for a company to dictate which scripting language their environment will support. Shell scripts are a bit different though because if you write a large enough software system on a unix-like OS you'll probably want to write a few shell scripts here and there to glue things together, so forbidding them completely would be a bit silly and counterproductive. Saying "avoid shell scripts, if you really have to write one it must be simple and use POSIX sh" is not particularly insane to me. But anyway my argument was more about my opinion about a developer talking for myself, not a company style guide. Life's too short to learn two shell dialects so I can either learn POSIX which will work basically everywhere and will let me write any simple script just fine or write Bash whose added complexity I probably won't need or even want. The fact that I'm an embedded dev probably biases my view though, I generally target environments where bash isn't an option anyway.

nurettin 8y ago

Probably because he can't use bash code in his BusyBox based router

pas 8y ago
And what's the magically amazing script that anyone would like to run on routers and AIXes alike, that it has to be POSIX portable? :)