On 2016-08-12 22:52, Mattias Andrée wrote:
Also, the names of shells conventionally end with
sh, just do go with ssh (which incidentally is not
a shell but ends with “sh” because the full name ends
with “shell”.)
On Fri, 12 Aug 2016 23:48:29 +0200
Mattias Andrée <maand...@kth.se> wrote:
Sorry for replying before reading, but I don't think a
single-character name is a good idea. Two-characters
should also be avoided, but it's acceptable. The number
of available names are severely limited and introduces
an unnecessarily high risk of collision. Short names,
and single-character name in particular, are best left
for user-defined aliases.
I will probably not read this message, because
writing another shell is not on my priority list.
On Fri, 12 Aug 2016 22:41:16 +0100
<ra...@openmailbox.org> wrote:
> Hello!
>
> GNU Bash is 138227 lines of code. I wrote a simpler
> shell* in 800 lines: https://notabug.org/rain1/s/
>
> *It is not a true POSIX shell. You can't run existing
> scripts with it. It's technically just a command
> interpreter.
>
> With that out the way here's an overview of how it
> works:
>
> Tokenization [tokenizer.c]: Instead of the strange and
> complex way that normal shells work (where "$X" is
> different to $X for example) s works by a strict
> tokenize -> variable expansion -> parse -> execute
> pipeline. This makes it much easier to program with and
> less likely for scripts to break simply because your
> CWD has a space in it.
>
> Variable expansion [variables.c]: The expander supports
> both $FOO and ${FOO} syntax, it just resolves
> environment variables.
>
> Parsing [parser.c]: There are just 3 binary operations
> |, && and || and '&' optional at the end of a line.
> There is no "if" or looping or anything. parser.c is 85
> lines of code and uses my region [region.c] based
> allocator to simplify teardown of the structure when it
> needs to be free'd.
>
> [interpreter.c] The interpreter is a simple recursive
> process that walks the AST, creating pipes and forking
> off children.
>
> [supporting/*.c] Instead of redirection operators like
> <,
> > and >> being part of the language they are simply
> > provided as supporting programs
> that should be added to the $PATH: < is basically just
> cat. The redirection operators are all packaged together
> in busybox style. Similarly glob is not part of the
> language, it is a 20 line script instead. You use it
> like this: glob rm *py
>
> [builtins.c] Of course a shell cannot do everything by
> external tools - so the builtins cd, source, set, unset
> are provided (and treated specially by the interpreter).
>
> It can run scripts you supply, shebang works, using it
> in a terminal interactively works. In theory enough for
> practical every day use.
>
> Except for the low linecount (it is even smaller than
> execline) and simplicity of the lexical aspect of the
> shell language it does not have strong benefits over
> existing shells (especially since it is not POSIX
> compatible) but I hope that the code may be interesting
> or refreshing to others who are unhappy with the excess
> of bloat most software has.
>
>
such stupid comments Mattias!
