Ash Vs Bash
Ash Vs Bash
[For reference, I'm talking about Ash in Alpine Linux here, which is part of BusyBox.]
I thought I knew the big differences, but it turns out I've had false assumptions for years. Ash does support [[ double square brackets ]] and (as best I can tell) all of Bash's logical trickery inside them. It also supports ${VARIABLE_SUBSTRINGS:5:12}` which was another surprise.
At this stage, the only things I've found that Bash can do that Ash can't are:
- Arrays, which Bash doesn't seem to do well anyway
- Brace expansion, which is awesome but I can live without it.
What else is there? Did Ash used to be more limited? The double square bracket thing really surprised me.
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What have you found bad about bash arrays? I have some simple usage of those (in bash) and they work fine.
As far as I've seen, they don't provide any advantage over a string with spaces, which doesn't work well either when you've got values with spaces:
not_what_you_think=( "a b" "c" "d" ) for sneaky in ${not_what_you_think[@]}; do echo "This is sneaky: ${sneaky}" doneThis is sneaky: a This is sneaky: b This is sneaky: c This is sneaky: dYou should put some quotes where you use the array:
not_what_you_think=( "a b" "c" "d" ) for sneaky in "${not_what_you_think[@]}"; do echo "This is sneaky: ${sneaky}" done This is sneaky: a b This is sneaky: c This is sneaky: dAaaaah! Thank you kind stranger. It never would have occurred to me to quote an array!
If you run your scripts through https://shellcheck.net it'll pick up things like this. Also available as a Linux package for offline use.
I too would like to know. Thank you.