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Bashing the Bash – Replacing Shell Scripts with Python (2017)

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Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#61

Post by Arnavion »

deathanatos wrote: post #55
yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

We had some problem, roughly, "run a tool on all YAML files in the directory" or something. The first attempt that led to a production outage: (It is late, bash examples are approximate. Don't sweat the syntax.) the_tool *.yaml There weren't any YAML files, so argv[1] was literally "*.yaml", which then wasn't found, leading to errors, etc. shopt -s nullglob the_tool *.yaml (Don't even get me started on how there's sh…

    find . -maxdepth 1 -name '*.yaml' -print0 | xargs -r0 the_tool
>To say "you're holding it wrong" is just folly. Bash is worthy of the same treatment that "A Fractal of Bad Design" gave PHP, and it has no place in anything that wants to call itself engineering.

If you have a problem that involves "run a command with a list of parameters but not if the list is empty" and you don't immediately think of `xargs -r`, then consider that it's because you don't understand the tools, not because the tools are bad.

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#62

Post by kafkaIncarnate »

Brian_K_White wrote: post #59

I have ksh scripts I wrote over 20 years ago on xenix, which still work today on bash or ksh. Meanwhile I have python apps that didn't make it a year. Any particular version of Python is a saner choice, if you could pick one and freeze it retroactively for the last 20 years and for at least the next 20. But that is not how Python works. Python breaks every 11 minutes. I would not write anything in Python that I cared…

That's what Python2.7 is and why every major proprietary product won't adopt anything else. It's also why it won't go away.

All of my Python 2.6-2.7 scripts haven't been touched in 10 years in production and they aren't likely to ever be updated. I actually now refuse to write new Python that isn't compatible with both 2&3 for this reason. Python3 refuses to stabilize.

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#63

Post by Izkata »

deathanatos wrote: post #55
yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

We had some problem, roughly, "run a tool on all YAML files in the directory" or something. The first attempt that led to a production outage: (It is late, bash examples are approximate. Don't sweat the syntax.) the_tool *.yaml There weren't any YAML files, so argv[1] was literally "*.yaml", which then wasn't found, leading to errors, etc. shopt -s nullglob the_tool *.yaml (Don't even get me started on how there's sh…

My preferred way under those conditions would be more along the lines of "see if a safe command fails, do the desired command if not", like:

  if ls *.yaml > /dev/null; then
    the_tool *.yaml
  fi

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#64

Post by yjftsjthsd-h »

drewcoo wrote: post #46
readingnews wrote: post #36

I have some bad news for you, from a long, long, long time CS/EE/Sysadmin person: I can probably run my bash script on every linux I ever touched. I can probably have that python code break on half of the linux boxen I use. This one does not have module X installed. This one is too old, this one is too new, this python is not holding its mouth just at the right angle to work. Yeah, bash bash all you want. I have pull…

But which one is more likely to also run on Windows? /s

... Hilariously, I think shell might actually win that; neither is installed by default, but you get some sort of bash/sh with any of interix, WSL1/2, git, cygwin, or mingw.

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#65

Post by kafkaIncarnate »

noasaservice wrote: post #30

Im dealing with some python3 crap today on my main laptop. Primarily, because of a library I compiled and installed, I'm getting other nasty side effects form it. Primarily that protonvpn-cli isnt now running becasue of some broken library. I've never had bash break like that. Quirks, sure. But never this sort of brokenness.

I had a similar problem with the YouTube plugin for Kodi recently. Turned out to be some weird Python 3.10 regression that took over a month to fix.

For ProtonVPN you can also use the OpenVPN config files they provide to avoid any Python client issues. Ironically I have a Bash script written around that to generate individual ovpn files as needed from the zip for myself.

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#66

Post by theteapot »

deathanatos wrote: post #55
yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

We had some problem, roughly, "run a tool on all YAML files in the directory" or something. The first attempt that led to a production outage: (It is late, bash examples are approximate. Don't sweat the syntax.) the_tool *.yaml There weren't any YAML files, so argv[1] was literally "*.yaml", which then wasn't found, leading to errors, etc. shopt -s nullglob the_tool *.yaml (Don't even get me started on how there's sh…

Didn't know "Fractal of Bad Design" even existed. I like aspects of PHP. Sorry.

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#67

Post by theteapot »

deathanatos wrote: post #55
yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

We had some problem, roughly, "run a tool on all YAML files in the directory" or something. The first attempt that led to a production outage: (It is late, bash examples are approximate. Don't sweat the syntax.) the_tool *.yaml There weren't any YAML files, so argv[1] was literally "*.yaml", which then wasn't found, leading to errors, etc. shopt -s nullglob the_tool *.yaml (Don't even get me started on how there's sh…

What happens if someone runs `the_tool this-file-does-not-exist.yaml` or the yaml file is removed by some other means before you get a chance to process it? Does your world also come tumbling down in these cases? If yes, please stop blaming Bash for it.

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#68

Post by zaphirplane »

deathanatos wrote: post #55
yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

We had some problem, roughly, "run a tool on all YAML files in the directory" or something. The first attempt that led to a production outage: (It is late, bash examples are approximate. Don't sweat the syntax.) the_tool *.yaml There weren't any YAML files, so argv[1] was literally "*.yaml", which then wasn't found, leading to errors, etc. shopt -s nullglob the_tool *.yaml (Don't even get me started on how there's sh…

This isn’t you are holding it wrong It is in the “do as I want not as I say” category

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#69

Post by Xavdidtheshadow »

yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

> obscure and difficult-to-predict

I mean, I think there's something to that. Bash has a lot of arcane rules; I personally never write an `if` statement right, what with the `[[` vs `[` and having to surround the condition with whitespace. I find that bash scripts carry a million little gotchas that will cause variables to not evaluate/expand the way you'd expect.

Say what you will about Python, but it's much easier to reason about what a script will do as compared to bash (unless the bash is _extremely_ simplistic).

Re: Bashing the Bash – Replacing Shell Scripts with Python (2017)

#70

Post by 1vuio0pswjnm7 »

deathanatos wrote: post #55
yjftsjthsd-h wrote: post #8

I was hoping someone finally had a library or something to make python good at the things shell does well (mostly, running stuff and piping output around). If only. This really just reads like someone who doesn't know shell and does know python, but thinks the problem is the tool. They continually describe shell with phrases like "obscure and difficult-to-predict" while talking through things that are either obvious…

We had some problem, roughly, "run a tool on all YAML files in the directory" or something. The first attempt that led to a production outage: (It is late, bash examples are approximate. Don't sweat the syntax.) the_tool *.yaml There weren't any YAML files, so argv[1] was literally "*.yaml", which then wasn't found, leading to errors, etc. shopt -s nullglob the_tool *.yaml (Don't even get me started on how there's sh…

Personally, I never use bash for scripting. I use the system's scripting shell, Debian's Dash or NetBSD Ash. Rhetorical question: If Bash was great for shell scripting, why doesn't the OS project choose it for scripting. When I compile the OS kernel and userland, the project (NetBSD) uses shell scripts not Python. Not suggesting the shell is necessarily better but I am suggesting it works and people understand it.

There are many ways to run a command on every .yaml file in a directory. Personally I like using xtrace. Something like:

   echo cd the_directory > 1.sh
   echo "test -f *.yaml" >> 1.sh
   ls -1 *.yaml|sed 's/^/the_tool /' >> 1.sh
   chmod +x 1.sh
   less 1.sh
   sh -ex 1.sh
As mostly a day-to-day shell user who automates some things, I do not use Python. Never had an outage.
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