Safe ways to do things in bash
161–170 of 255 posts
Re: Safe ways to do things in bash
#162If you reached a point where you need to require bash and not a posix shell and need to enforce these rules just use python or lua if you can or some scheme or whatever else... it's not worth the wasted time hunting bash cruft. if you are on busybox with ash none of this is helping (except shellcheck which is great).
Bash is available on almost every system. The portability is desirable sometimes.
How many people need that portability? Most of the shell scripts are quick work that needs to run on small amount of environments.
Re: Safe ways to do things in bash
#163Backticks are very error prone $(cat foo.txt) is much more explicit and visually clearer for command substitution.
fish forces you to use braces. (Even without the dollar sign.)
Re: Safe ways to do things in bash
#164Earlier quoted context omitted.
I have made a lot of DNS products and doing the same thing happening here is a few lines of code in most any language. This code, while entertaining, cannot handle very simple DNS packets because of its "compression encoding.
This is ran behind PowerDNS, which handles the compression prior to handing off to this code, so that shouldn't be a problem.
Which means it’s not really doing any of the heavy lifting.
Re: Safe ways to do things in bash
#165Step 1 to write safer shell scripts: use a safer shell. Zsh gives the user much more control, has safer defaults, and is itself quite portable (even if Zsh scripts are not portable to other shells).
unfortunately, zsh is installed on probably about 1% of Linux systems worldwide. maybe it can be installed almost anywhere, but the fact is it isn't, and you might as well use Python or something at that point.
And how many on the system that you actually touch? How hard is it to (ask to) install a new shell?
Obviously if you're distributing your script publicly no one would write that in zsh compatible way.
Re: Safe ways to do things in bash
#166A tip from me, based on a mistake I made yesterday: don't `source ~/.bash_history` instead of `~/.bash_profile`. (Luckily it entered vim relatively soon, from where I could kill the process).
At least it's not recursive.
Re: Safe ways to do things in bash
#167Earlier quoted context omitted.
I did a talk on this a while ago: https://www.youtube.com/watch?v=pb3k0sGKrjQ&t=457s 'Take bash seriously'
It's time we need a better shell than bash instead of thinking it's great after bleeding with it for years and gets used to it.
I’d vote for PowerShell in a heartbeat. It passes real objects instead of strings. It’s cross platform and open source. It’s imperative but borrows some functional concepts.
Re: Safe ways to do things in bash
#168> POSIX mandates /bin/sh Nope. On the contrary, it says: Applications should note that the standard PATH to the shell cannot be assumed to be either /bin/sh or /usr/bin/sh Source: http://pubs.opengroup.org/onlinepubs/009695399/utilities/sh.... A pedantically-compliant shell script should not have shebang at all.
Distros that places symlinks to bash in all those locations solves this, and allows all POSIX-compliant shebangs for sh and bash. On Arch Linux, /bin/bash, /bin/sh and /usr/bin/sh all point to /usr/bin/bash.
Re: Safe ways to do things in bash
#169> POSIX mandates /bin/sh Nope. On the contrary, it says: Applications should note that the standard PATH to the shell cannot be assumed to be either /bin/sh or /usr/bin/sh Source: http://pubs.opengroup.org/onlinepubs/009695399/utilities/sh.... A pedantically-compliant shell script should not have shebang at all.
What's wrong with `#!/usr/bin/env sh`?
"/usr/bin/env" is relying on a binary being present in a specific location just as much as relying on a binary being present in "/bin/bash". For most distros and BSDs, "/usr/bin/env" is more likely to be present, but it's not guaranteed for neither "/bin/bash" nor "/usr/bin/env".
Re: Safe ways to do things in bash
#170I've written a ridiculous amount of shell script in my day, especially when doing "devops" before we had a term like "devops" to describe it. I've fallen in almost every pit bash has. With that background, here is my opinion. 1. This article contains excellent advice and should be starred for later retrieval. 2. Having basic scripting skills will make you a way better programmer. Many times I've done huge refactors a…
I think it's time people start using something better than bash/zsh that is decades old, like fish or even come up with a more modern shell. Even by looking at these examples, you see it has less verbosity like "then" and "do", you can reference arguments as $argv instead of cryptic $@ and exit status code as $status instead of $? which is confusing with $! and the likes. https://blog.codeship.com/lets-talk-about-she…
I think a big issue is that bash is available everywhere, while fish might not be.
There's also the fact that a lot of us have fancy dotfiles for our work/home computers, and switching to another shell would mean having to rewrite them in the target shell language.