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Can we actually improve the POSIX shell? Can we reform it, perhaps into a "D-shell," that is an LR-parsed language? AWK had a yacc grammar for many years. Why

by chasil 4y ago

Can we actually improve the POSIX shell? Can we reform it, perhaps into a "D-shell," that is an LR-parsed language? AWK had a yacc grammar for many years. Why can't this be the language of the shell, at least for the sake of maintainability and comprehension? https://archive.fosdem.org/2018/schedule/event/code_parsing_posix_s_hell/ https://archive.fosdem.org/2018/schedule/event/code_parsing_...

msla 4y ago
The problem with making a shell more like a "real" interpreter REPL is the purpose of a shell: Running arbitrary programs not known to the author of the shell, such that any unknown word in a shell script is probably the name of a program as opposed to a misspelled reserved word or variable name. Those programs having arbitrary command-line arguments and having to operate on files with arbitrary names is another complexity.
- pasc1878 4y ago
  It has been done. See xonsh a python shell which manages the distinction you mention. Also see scsh and rash for scheme Fish for non posix but sane syntax
- actionfromafar 4y ago
  It's interesting to see how so many things grow into each other. A shell is what you say, but there are many efforts to change that. Bash has its magic autocomplete which knows about options of many, many programs. Powershell has an object-model with knowledge of many of its commands.
deafpolygon 4y ago
> Can we actually improve the POSIX shell? PowerShell?
- chasil 4y ago
  No, that won't work. $ ll /bin/dash -rwxr-xr-x 1 root root 85368 Jan 5 09:52 /bin/dash If you can make Powershell in a binary that size, then you have a valid point.
  - shubhamkrm 4y ago
    But why? Storage is much cheaper today than it was in the 80s. While I myself don’t like huge Electron apps, trying to save every byte of storage is simply not worth it.
    - chasil 4y ago
      Embedded applications on smaller systems are why. The POSIX shell is common, from the largest supercomputer down to the smallest ARM. I don't think that there will be any new developments covering that full scope.
      - deafpolygon 4y ago
        Embedded systems don't exclude PowerShell from being a replacement for POSIX shells. Maybe embedded systems should not strive to be POSIX.
      - pjmlp 4y ago
        Many embedded systems hardly have any shell, and even when they do, it isn't bash (which isn't POSIX anyway), rather a tiny subset with the basic tooling for maintenance.

by chasil 4y ago

msla 4y ago

The problem with making a shell more like a "real" interpreter REPL is the purpose of a shell: Running arbitrary programs not known to the author of the shell, such that any unknown word in a shell script is probably the name of a program as opposed to a misspelled reserved word or variable name. Those programs having arbitrary command-line arguments and having to operate on files with arbitrary names is another complexity.

pasc1878 4y ago
It has been done. See xonsh a python shell which manages the distinction you mention. Also see scsh and rash for scheme Fish for non posix but sane syntax
actionfromafar 4y ago
It's interesting to see how so many things grow into each other. A shell is what you say, but there are many efforts to change that. Bash has its magic autocomplete which knows about options of many, many programs. Powershell has an object-model with knowledge of many of its commands.

deafpolygon 4y ago

> Can we actually improve the POSIX shell? PowerShell?

chasil 4y ago
No, that won't work. $ ll /bin/dash -rwxr-xr-x 1 root root 85368 Jan 5 09:52 /bin/dash If you can make Powershell in a binary that size, then you have a valid point.
- shubhamkrm 4y ago
  But why? Storage is much cheaper today than it was in the 80s. While I myself don’t like huge Electron apps, trying to save every byte of storage is simply not worth it.
  - chasil 4y ago
    Embedded applications on smaller systems are why. The POSIX shell is common, from the largest supercomputer down to the smallest ARM. I don't think that there will be any new developments covering that full scope.
    - deafpolygon 4y ago
      Embedded systems don't exclude PowerShell from being a replacement for POSIX shells. Maybe embedded systems should not strive to be POSIX.
    - pjmlp 4y ago
      Many embedded systems hardly have any shell, and even when they do, it isn't bash (which isn't POSIX anyway), rather a tiny subset with the basic tooling for maintenance.