91–100 of 114 posts
In the 2000s, I was running extensive sets of simulations and data reduction scripts for a scientific experiment, and I was heavy relying on scripts to run the programs, collect the results, and distribute them over several servers. At first I developed those scripts using bash, but I needed to do math and complex iterations over file names and different parameter files, and I continuously stumbled upon weird behavio…
A lot of commenters suggesting "pipefail" aren't realising the full extent of the problem. Here's an example that might be clearer, from https://david.rothlis.net/shell-set-e This prints “a”, as you’d expect: set -e myfun() { printf a; false; printf b; } myfun printf c ...because the “set -e” terminates the whole script immediately after running the “false” command. But this script prints “a-b-True”, where some peopl…
https://www.oilshell.org/release/latest/doc/error-handling.h...
Here's a demo of how Oil fixes it, which I mentioned in this thread:
$ osh hn.sh
a-b-True
$ osh -o strict_errexit hn.sh
if myfun; then
^~
hn.sh:3: errexit was disabled for this construct
if myfun; then
^~~~~
hn.sh:3: fatal: Can't run a proc while errexit is disabled. Use 'try' or wrap it in a process with $0 myproc
$ oil hn.sh
A lot of commenters suggesting "pipefail" aren't realising the full extent of the problem. Here's an example that might be clearer, from https://david.rothlis.net/shell-set-e This prints “a”, as you’d expect: set -e myfun() { printf a; false; printf b; } myfun printf c ...because the “set -e” terminates the whole script immediately after running the “false” command. But this script prints “a-b-True”, where some peopl…
It's always been odd that Bash has hundreds of options for controlling its behaviour in non-standard ways, via "set", "shopt" and environment variables, but it's never had an option to make "-e" do the obviously natural behaviour,, I encountered the "you can't enable -e" problem years ago in a complex build system that used Bash to build embedded sysem components. The scripts were all designed on the assumption that…
This is harder than it sounds! :) There's arguably not a natural behavior for shell, because $? is overloaded in Unix. It can mean success/failure or it can mean true/false/error.
https://www.oilshell.org/release/latest/doc/error-handling.h...
Oil introduces some new idioms that led you distinguish between the two paradigms, so it's best to change the way you write scripts. It's not something bash can magically fix.
https://www.oilshell.org/release/latest/doc/idioms.html#erro...
That said, just running your scripts with Oil will flag problems, acting like a ShellCheck at runtime, catching things that ShellCheck can't.
See the sibling reply for a demo, and this comment:
I can highly recommend using Shellcheck [0] when writing Bash, it also has extensions for VS Code and other IDE's. It makes writing Bash much easier. [0] https://github.com/koalaman/shellcheck
Agree, this is the way.
Example here: https://news.ycombinator.com/item?id=33122256
All of these problems are fixed in OSH. It runs your bash scripts but you can also opt into correct error handling. The simple invariant is that it doesn't lose an exit code, and non-zero is fatal by default. See https://www.oilshell.org/release/latest/doc/error-handling.h... Oil 0.10.0 - Can Unix Shell Error Handling Be Fixed Once and For All? https://www.oilshell.org/blog/2022/05/release-0.10.0.html This took quite…
https://news.ycombinator.com/item?id=33122256
They're separate things because introducing MORE error handling can make your script incompatible with bash, for people who want to write code that's portable to 2 shells :-/
I can highly recommend using Shellcheck [0] when writing Bash, it also has extensions for VS Code and other IDE's. It makes writing Bash much easier. [0] https://github.com/koalaman/shellcheck
I moved over to shellharden a while ago. It can actually apply the suggestions it makes. Aside from that, my employer is somewhat disapproving for GPLv3 tools, but MPL that shellharden uses is essentially auto-approved. https://github.com/anordal/shellharden
In the 2000s, I was running extensive sets of simulations and data reduction scripts for a scientific experiment, and I was heavy relying on scripts to run the programs, collect the results, and distribute them over several servers. At first I developed those scripts using bash, but I needed to do math and complex iterations over file names and different parameter files, and I continuously stumbled upon weird behavio…
(from the bash manual)
The ERR trap [same rules as set -e] is not executed if the
failed command is part of the command list immediately following
a while or until keyword, part of the test in an if statement,
part of a command executed in a && or || list except the command
following the final && or || [...]All of these problems are fixed in OSH. It runs your bash scripts but you can also opt into correct error handling. The simple invariant is that it doesn't lose an exit code, and non-zero is fatal by default. See https://www.oilshell.org/release/latest/doc/error-handling.h... Oil 0.10.0 - Can Unix Shell Error Handling Be Fixed Once and For All? https://www.oilshell.org/blog/2022/05/release-0.10.0.html This took quite…
Never used OilShell (OSH) before, but this opening line on their home page struck me: > … and it's a new language for Python and JavaScript users who avoid shell! Why not work towards using python/JavaScript as shell languages? There was a HN thread a few days ago on Xonsh, the main python attempt at this which looks nice to me, which naturally got a lot of anti-anti-bash energy. But if we want better shell ergonomic…
I always refer to this awesome answer to that question:
A lot of commenters suggesting "pipefail" aren't realising the full extent of the problem. Here's an example that might be clearer, from https://david.rothlis.net/shell-set-e This prints “a”, as you’d expect: set -e myfun() { printf a; false; printf b; } myfun printf c ...because the “set -e” terminates the whole script immediately after running the “false” command. But this script prints “a-b-True”, where some peopl…