This may make some people pull their hair out, but I’d love to hear some arguments. I’ve had the impression that people really don’t like bash, not from here, but just from people I’ve worked with.
There was a task at work where we wanted something that’ll run on a regular basis, and doesn’t do anything complex aside from reading from the database and sending the output to some web API. Pretty common these days.
I can’t think of a simpler scripting language to use than bash. Here are my reasons:
- Reading from the environment is easy, and so is falling back to some value; just do
${VAR:-fallback}; no need to write another if-statement to check for nullity. Wanna check if a variable’s set to something expected?if [[ <test goes here> ]]; then <handle>; fi - Reading from arguments is also straightforward; instead of a
import os; os.args[1]in Python, you just do$1. - Sending a file via HTTP as part of an
application/x-www-form-urlencodedrequest is super easy withcurl. In most programming languages, you’d have to manually open the file, read them into bytes, before putting it into your request for the http library that you need to import.curlalready does all that. - Need to read from a
curlresponse and it’s JSON? Reach forjq. - Instead of having to set up a connection object/instance to your database, give
sqlite,psql,duckdbor whichever cli db client a connection string with your query and be on your way. - Shipping is… fairly easy? Especially if docker is common in your infrastructure. Pull
Ubuntuordebianoralpine, install your dependencies through the package manager, and you’re good to go. If you stay within Linux and don’t have to deal with differences in bash and core utilities between different OSes (looking at you macOS), and assuming you tried to not to do anything too crazy and bring in necessary dependencies in the form of calling them, it should be fairly portable.
Sure, there can be security vulnerability concerns, but you’d still have to deal with the same problems with your Pythons your Rubies etc.
For most bash gotchas, shellcheck does a great job at warning you about them, and telling how to address those gotchas.
There are probably a bunch of other considerations but I can’t think of them off the top of my head, but I’ve addressed a bunch before.
So what’s the dealeo? What am I missing that may not actually be addressable?
“Use the best tool for the job, that the person doing the job is best at.” That’s my approach.
I will use bash or python dart or whatever the project uses.
One thing that I don’t think anyone else has mentioned is data structures. Bash does have arrays and hashmaps at least but I’ve found that working with them is significantly more awkward than in e.g. python. This is one of several reasons for why bash doesn’t scale up well, but sure for small enough scripts it can be fine (if you don’t care about windows)
I think I mentioned it, but inverse: The only data type I’m comfortable with in bash are simple string scalars; plus some simple integer handling I suppose. Once I have to think about stuff like
"${foo[@]}"and the like I feel like I should’ve switched languages already.Plus I rarely actually want arrays, it’s way more likely I want something in the shape of
@dataclass(frozen=True) class Foo: # … foos: set[Foo] = …
We are not taking about use of Bash in dev vs use Bash in production. This is imho incorrect question that skirts around the real problem in software development. We talk about use of Bash for simple enough tasks where code is rarely changed ( if not written once and thrown away ) and where every primitive language or DSL is ok, where when it comes to building of medium or complex size software systems where decomposition, complex data structures support, unit tests, error handling, concurrency, etc is a big of a deal - Bash really sucks because it does not allow one to deal with scaling challenges, by scaling I mean where you need rapidly change huge code base according changes of requirements and still maintain good quality of entire code. Bash is just not designed for that.
But not everything needs to scale, at least, if you don’t buy into the doctrine that everything has to be designed and written to live forever. If robust, scalable solutions is the nature of your work and there’s nothing else that can exist, then yeah, Bash likely have no place in that world. If you need any kind of handling more complicated than just getting an error and doing something else, then Bash is not it.
Just because Bash isn’t designed for something you want to do, doesn’t mean it sucks. It’s just not the right tool. Just because you don’t practice law, doesn’t mean you suck; you just don’t do law. You can say that you suck at law though.
If your company ever has >2 people, it will become a problem.
You’re speaking prophetically there and I simply do not agree with that prophecy.
If you and your team think you need to extend that bash script to do more, stop and consider writing it in some other languages. You’ve move the goalpost, so don’t expect that you can just build on your previous strategy and that it’ll work.
If your “problem” stems from “well your colleagues will not likely be able to read or write bash well enough”, well then just don’t write it in bash.
Honestly, if a script grows to more than a few tens of lines I’m off to a different scripting language because I’ve written enough shell script to know that it’s hard to get right.
Shellcheck is great, but what’s greater is a language that doesn’t have as many gotchas from the get go.
I’ve worked in bash. I’ve written tools in bash that ended up having a significant lifetime.
Personally, you lost me at
reading from the database
Database drivers exist for a reason. Shelling out to a database cli interface is full of potential pitfalls that don’t exist in any language with a programmatic interface to the database. Dealing with query parameterization in bash sounds un-fun and that’s table stakes, security-wise.
Same with making web API calls. Error handling in particular is going to require a lot of boilerplate code that you would get mostly for free in languages like Python or Ruby or Go, especially if there’s an existing library that wraps the API you want to use in native language constructs.
This is almost a strawman argument.
You don’t have to shell out to a db cli. Most of them will gladly take some SQL and spit out some output. Now that output might be in some tabular format with some pretty borders around them that you have to deal with, if you are about the output within your script, but that’s your choice and so deal with it if it’s within your comfort zone to do so. Now if you don’t care about the output and just want it in some file, that’s pretty straightforward, and it’s not too different from just some cli that spits something out and you’ve redirected that output to a file.
I’ve mentioned in another comment where if you need to accept input and use that for your queries, psql is absolutely not the tool to use. If you can’t do it properly in bash and tools, just don’t. That’s fine.
With web API calls, same story really; you may not be all that concerned about the response. Calling a webhook? They’re designed to be a fire and forget, where we’re fine with losing failed connections. Some APIs don’t really follow strict rules with REST, and will gladly include an “ok” as a value in their response to tell you if a request was successful. If knowing that is important to the needs of the program, then, well, there you have it. Otherwise, there are still ways you can get the HTTP code and handle appropriately. If you need to do anything complex with the contents of the response, then you should probably look elsewhere.
My entire post is not to say that “you can do everything in bash and you should”. My point is that there are many cases where bash seems like a good sufficient tool to get that simple job done, and it can do it more easily with less boilerplate than, say, Python or Ruby.
You can do everything in bash with things not written in bash, and the parts not written in bash would be alright.
I’m afraid your colleagues are completely right and you are wrong, but it sounds like you genuinely are curious so I’ll try to answer.
I think the fundamental thing you’re forgetting is robustness. Yes Bash is convenient for making something that works once, in the same way that duct tape is convenient for fixes that work for a bit. But for production use you want something reliable and robust that is going to work all the time.
I suspect you just haven’t used Bash enough to hit some of the many many footguns. Or maybe when you did hit them you thought “oops I made a mistake”, rather than “this is dumb; I wouldn’t have had this issue in a proper programming language”.
The main footguns are:
- Quoting. Trust me you’ve got this wrong even with
shellcheck. I have too. That’s not a criticism. It’s basically impossible to get quoting completely right in any vaguely complex Bash script. - Error handling. Sure you can
set -e, but then that breaks pipelines and conditionals, and you end up with really monstrous pipelines full ofpipefailnoise. It’s also extremely easy to forgetset -e. - General robustness. Bash silently does the wrong thing a lot.
instead of a
import os; os.args[1]in Python, you just do$1No. If it’s missing
$1will silently become an empty string.os.args[1]will throw an error. Much more robust.Sure, there can be security vulnerability concerns, but you’d still have to deal with the same problems with your Pythons your Rubies etc.
Absolutely not. Python is strongly typed, and even statically typed if you want. Light years ahead of Bash’s mess. Quoting is pretty easy to get right in Python.
I actually started keeping a list of bugs at work that were caused directly by people using Bash. I’ll dig it out tomorrow and give you some real world examples.
Agreed.
Also gtfobins is a great resource in addition to shellcheck to try to make secure scripts.
For instance I felt upon a script like this recently:
#!/bin/bash # ... some stuff ... tar -caf archive.tar.bz2 "$@"Quotes are OK, shellcheck is happy, but, according to gtfobins, you can abuse tar, so running the script like this:
./test.sh /dev/null --checkpoint=1 --checkpoint-action=exec=/bin/shends up spawning an interactive shell…So you can add up binaries insanity on top of bash’s mess.
Quotes are OK, shellcheck is happy, but, according to gtfobins, you can abuse tar, so running the script like this: ./test.sh /dev/null --checkpoint=1 --checkpoint-action=exec=/bin/sh ends up spawning an interactive shell…
This runs into a part of the unix philosophy about doing one thing and doing it well: Extending programs to have more (absolutely useful) functionality winds up becoming a security risk. The shell is generally geared towards being a collection of shortcuts rather than a normal, predictable but tedious API.
For a script like that you’d generally want to validate that the input is actually what you expect if it needs to handle hostile users, though. It’ll likely help the sleepy users too.
- Quoting. Trust me you’ve got this wrong even with
What gave you the impression that this was just for development? Bash is widely used in production environments for scripting all over enterprises. The people you work with just don’t have much experience at lots of shops I would think.
It’s just not wise to write an entire system in bash. Just simple little tasks to do quick things. Yes, in production. The devops world runs on bash scripts.
Bash is widely used in production environments for scripting all over enterprises.
But it shouldn’t be.
The people you work with just don’t have much experience at lots of shops I would think.
More likely they do have experience of it and have learnt that it’s a bad idea.
I’ve never had that impression, and I know that even large enterprises have Bash scripts essentially supporting a lot of the work of a lot of their employees. But there are also many very loud voices that seems to like screaming that you shouldn’t use Bash almost at all.
You can take a look at the other comments to see how some are entirely turned off by even the idea of using bash, and there aren’t just a few of them.
This Lemmy thread isn’t representative of the real world. I’ve been a dev for 40 years. You use what works. Bash is a fantastic scripting tool.
