3 ms·

Just to clarify, Bash is installed under /usr/local because it’s from packages and not part of the base system. The base shell, ksh, is at /bin/ksh. You proba

by adamrt 5y ago

Just to clarify, Bash is installed under /usr/local because it’s from packages and not part of the base system. The base shell, ksh, is at /bin/ksh. You probably know that but I just felt like being pedantic this morning :).

chasil 5y ago
...and that ksh descended from pdksh, and is distributed as the oksh portable project here: https://github.com/ibara/oksh https://github.com/ibara/oksh The MirBSD Korn Shell also descended from pdksh, and it can be found here: http://www.mirbsd.org/mksh.htm http://www.mirbsd.org/mksh.htm I don't know about the feature differences and code quality between these two; they both implement most of ksh88, and a small amount of ksh93. I prefer mksh when I need something more than a POSIX shell.
yabones 5y ago
Yes, absolutely true. The idea is that `ksh` is good enough, and the extra features of bash are extraneous or unnecessary, making it an add-on rather than a core feature. It's an interesting idea, and while I feel bash is absolutely 'good enough' to be part of the base system, I wouldn't want zsh or fish part of my base system - so it's then a matter of opinion whose shell is bloat and whose is essential. So I respect their decision to not include bash in the base image - it's meant to be uncompromisingly lean and simple.
- chasil 5y ago
  Another issue is size. This is what I see on CentOS: $ ls -l /bin/bash /bin/dash /bin/mksh -rwxr-xr-x. 1 root root 964536 Nov 22 2019 /bin/bash -rwxr-xr-x. 1 root root 113536 Nov 5 2018 /bin/dash -rwxr-xr-x. 1 root root 296192 Jan 27 2018 /bin/mksh The Debian Almquist shell has nearly nothing beyond POSIX (I believe that local function variables are the only extension). This is the Ubuntu system shell, and it tolerates no bashisms. Alternate POSIX shell implementations in OCaml (and somewhat ADA) accuse Almquist of not using formal grammars and imply that dash is not a safe implementation. https://www.irif.fr/_media/rencontres/pps2018/regis-gianas.pdf https://www.irif.fr/_media/rencontres/pps2018/regis-gianas.p... I would say that mksh implements 80% of bash functionality in much less space, and closely follows ksh88; mksh is also licensed such that Android uses it as /bin/sh. Apple has switched from bash to zsh. I don't know the motivations for this, but preferences for shells wax and wane. BSD doesn't include bash (in base) more because of license than code quality. POSIX seems to be all that we can agree on, but I do wish that standard could grow; it's stuck in the '70s.
  - petre 5y ago
    > Apple has switched from bash to zsh. I don't know the motivations for this GPLv3 vs BSD or MIT license. I lived zsh anyway, switched some of my BSD shells to it afterwards.
    - edgyquant 5y ago
      I love zsh but it’s history doesn’t segregate based on the tty and it locks up a lot during autocompletion for me (on Ubuntu.)
      - massysett 5y ago
        This is not typically the default setting in zsh (it is if it’s acting like ksh.) Your distributor has probably “helpfully” set it up this way. man zshoptions and look for “SHARE_HISTORY”.
        edgyquant 5y ago
        It's Ubuntu 18.04 with Oh My Zsh
      - petre 5y ago
        I'm using it without any plugins and disabled autocompletion anyway, because it just gets in the way irrespective of the shell. Like not completing tar filenames if it doesn't like the extension (tar axvf) even if the file is there. Modren distributions 'helpfully' enable completion by default. I don't like the fact that you have no way to clear the history buffer if you've accidentally dropped a password at the prompt. Bash has history -c. I don't have shared history enabled, you could unset that and it'll stop segregating. Anyway, zsh is a lot more versatile and familiar than tcsh for instance, so it's almost always my go to shell on FreeBSD as /bin/sh is quite limited, but also miles ahead of the Debian shell regarding features.
  - rsfinn 5y ago
    Apple avoids GPLv3-licensed software, which may explain why they continue to ship an older version of bash (3.2, the last GPLv2 version). Eventually they must have decided that was too outdated to keep as the default shell and switched to zsh, which has an MIT-derived license.

by adamrt 5y ago

chasil 5y ago

...and that ksh descended from pdksh, and is distributed as the oksh portable project here: https://github.com/ibara/oksh https://github.com/ibara/oksh The MirBSD Korn Shell also descended from pdksh, and it can be found here: http://www.mirbsd.org/mksh.htm http://www.mirbsd.org/mksh.htm I don't know about the feature differences and code quality between these two; they both implement most of ksh88, and a small amount of ksh93. I prefer mksh when I need something more than a POSIX shell.

yabones 5y ago

Yes, absolutely true. The idea is that `ksh` is good enough, and the extra features of bash are extraneous or unnecessary, making it an add-on rather than a core feature. It's an interesting idea, and while I feel bash is absolutely 'good enough' to be part of the base system, I wouldn't want zsh or fish part of my base system - so it's then a matter of opinion whose shell is bloat and whose is essential. So I respect their decision to not include bash in the base image - it's meant to be uncompromisingly lean and simple.

chasil 5y ago
Another issue is size. This is what I see on CentOS: $ ls -l /bin/bash /bin/dash /bin/mksh -rwxr-xr-x. 1 root root 964536 Nov 22 2019 /bin/bash -rwxr-xr-x. 1 root root 113536 Nov 5 2018 /bin/dash -rwxr-xr-x. 1 root root 296192 Jan 27 2018 /bin/mksh The Debian Almquist shell has nearly nothing beyond POSIX (I believe that local function variables are the only extension). This is the Ubuntu system shell, and it tolerates no bashisms. Alternate POSIX shell implementations in OCaml (and somewhat ADA) accuse Almquist of not using formal grammars and imply that dash is not a safe implementation. https://www.irif.fr/_media/rencontres/pps2018/regis-gianas.pdf https://www.irif.fr/_media/rencontres/pps2018/regis-gianas.p... I would say that mksh implements 80% of bash functionality in much less space, and closely follows ksh88; mksh is also licensed such that Android uses it as /bin/sh. Apple has switched from bash to zsh. I don't know the motivations for this, but preferences for shells wax and wane. BSD doesn't include bash (in base) more because of license than code quality. POSIX seems to be all that we can agree on, but I do wish that standard could grow; it's stuck in the '70s.
- petre 5y ago
  > Apple has switched from bash to zsh. I don't know the motivations for this GPLv3 vs BSD or MIT license. I lived zsh anyway, switched some of my BSD shells to it afterwards.
  - edgyquant 5y ago
    I love zsh but it’s history doesn’t segregate based on the tty and it locks up a lot during autocompletion for me (on Ubuntu.)
    - massysett 5y ago
      This is not typically the default setting in zsh (it is if it’s acting like ksh.) Your distributor has probably “helpfully” set it up this way. man zshoptions and look for “SHARE_HISTORY”.
      - edgyquant 5y ago
        It's Ubuntu 18.04 with Oh My Zsh
    - petre 5y ago
      I'm using it without any plugins and disabled autocompletion anyway, because it just gets in the way irrespective of the shell. Like not completing tar filenames if it doesn't like the extension (tar axvf) even if the file is there. Modren distributions 'helpfully' enable completion by default. I don't like the fact that you have no way to clear the history buffer if you've accidentally dropped a password at the prompt. Bash has history -c. I don't have shared history enabled, you could unset that and it'll stop segregating. Anyway, zsh is a lot more versatile and familiar than tcsh for instance, so it's almost always my go to shell on FreeBSD as /bin/sh is quite limited, but also miles ahead of the Debian shell regarding features.
- rsfinn 5y ago
  Apple avoids GPLv3-licensed software, which may explain why they continue to ship an older version of bash (3.2, the last GPLv2 version). Eventually they must have decided that was too outdated to keep as the default shell and switched to zsh, which has an MIT-derived license.