Bash is a terrible language, and needs to die.
Contrast that with:
subprocess.run("some_thing with-output")
subprocess.run("the_next_thing")
I guess it is the same situation with all programming -- diligent programmers can make it work, less disciplined users inflict pain upon all downstream users of poorly coded scripts
For a short while I was following https://github.com/matz/streem (from the original author of Ruby) with interest in possibly being adapted to superseed Bash. I have no idea how realistic that actually is.
I also use fish a lot, but it has a lot of it's own problems.
The thing about all these "shells" that really seperates them from Python (et all) is that they lookup commands from PATH and execute them directly. Anything else is simply not a shell language no matter how great it is at scripting.
("ls".execute() | "grep -i old".execute()).waitForProcessOutput(System.out, System.out)
It can also be written as
"ls".execute().or("grep -i old".execute()).waitForProcessOutput(System.out, System.out)
It's not exactly the same because it uses a thread and a buffer instead of an OS pipe but I guess it's close enough.
"Or" is the name of the "|" operator. From the looks of it it's impossible to overload "||" in groovy.
By the way the "|" operator and the "or" method both call "pipeTo" directly so a third way to write it would be:
"ls".execute().pipeTo("grep -i old".execute()).waitForProcessOutput(System.out, System.out)
for filename in os.listdir(os.curdir):
if 'old' in filename.lower():
print(filename)
The problem I have with a lot of shells is that their variable syntax is almost completely broken if you want to do anything slightly harder than trivial. A recent example I had was trying to write a script that reads a shell and executes the last line with some extra arguments. So that should be `PROG=$(tail -n1 commands.sh); creduce-script "$PROG"`, nothing hard about that... except the last line was `clang "-DFOO= " bar.c`.
A shell is a REPL designed to use quickly and easily for one-off jobs. Shell scripts are also sometimes just simpler to string together than referencing a whole new language.
ls | ? name -eq old
ls | ? Name -match '^old$'
But yes, this isn't Python.
You would write a script with os.listdir and 'if "old" in path' if you wanted to automate it.
If you were doing things interactively in a python minded OS, you might either have something much like shell is today(Maybe very stripped down without a focus on programming features beyond glob, expansion, and pipes), or you would have python library of misc utils.
Maybe you would do
x=ls() search(x, "old")
But that would be rather slow. Maybe you'd have some completely new model of text based interaction that was more menu driven and looked a lot like VS Code's command palette.
You'd press tab at the beginning of a line(Arbitrary easy to reach shortcut), and get your command pallet. Start typing and fuzzy search happens.
Select "Search filenames", and maybe that's a common enough snippet that it would be built in. Now you have that whole script, and your cursor is already in the search term field.
Press tab there. You get a menu of recently set variables, recently used short strings, etc, that the heuristic might want you to have.
With better UI we could afford a more explicit traditional language syntax.
Both scripting and shell could be a lot better.
* These languages prefer to operate on structured data. If it parses from json, you have a much easier time. But, most commands you'd invoke from the shell emit unstructured text by default. You can deal with this, but it's a pain point, and it means any serious scripting starts off with a "here's how you parse the output of <foo>", and several rounds of debugging.
* The shell's first and foremost usage is a user-facing interactive interface to the computer. Most of what you do is invoking other programs and seeing their output, and doing this is very easy. While python & ruby have REPLs, these are mostly focused on trying out language features or testing code, not invoking other programs, nor navigating a file tree. A lot of shell scripts start as 1-liners that grow and grow.
* Invoking other programs: In sh, invoking other programs is the primary activity, and it's relatively straightforward - you type the name of that program, press enter, and hope that it's on your path. In Python or Ruby, it requires importing the proper library, choosing the correct command, wrapping it and arguments, and ensuring everything escaped correctly. [Ruby _does_ have the backticks operator, which does actually make a lot of 1-off scripts easy, but this is not a panacea]
* In sh, a lot of the 'utility' programs like cut, sed, awk, grep, head, tail, etc., are standing in for the capabilities of the language itself. In pure Python or Ruby, you'd do these kinds of things with language built-ins. But, that's a learning curve, and perhaps a bit more error-prone than "| head".
* On top of all that, yes, momentum. If tomorrow you showed me a shell replacement for nix that was unambiguously* improved in every way, had excellent documentation, community support, and was actually pre-installed on every machine, it would still take a decade or more before it was really a default.
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I want it to happen, so I'd never discourage anyone from taking a swing. IMO, some of the top-level considerations that are necessary for making a successful sh alternative are:
* minimize the additional # of characters required to invoke a program with arguments, compared to bash.
* Decide which suite of typical utilities should actually be built-ins (i.e., things like cd, ls, cp, grep, curl), and make those standard library, built-in, without additional import or namespacing.
* Focus on an append-style workflow. Functional programing styles can kind of help here. Wrapping things in loops or blocks is a point of friction.
* An additional highly-desired feature which just isn't in sh by default, to overcome momentum. I have no idea what this would be. More reliability and better workflow are _nice_, but sh is sticky.
Bash is good at being a programmable shell, and bad at being a poor programming language. It's great to be able to express complex operations in the command line, but once you start putting them in files you're gonna have headaches.
i'm surprised how bash survives.. I think it's part of a few traditions that are tied to *nix, just like sysvinit, or raw string pipes as IPC .. they'll soon fall in sequence