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14 hours ago
3
namerefs (introduced in bash 4.0) act as aliases for other variables
they can also reference a specific element in an array, using declare -n ref='array[1234]'
using this, i have been playing with a neat nameref trick:
it uses the auxiliary array tmp to force an arithmetic context, in which it assigns the result of any arbitrary expression to an element of that array, then expands that same element. we can now create magic variables that evaluate any arbitrary expression.
here's a basic counter:
here's an example that computes the fibonacci numbers:
this is already very powerful, as it can do many magic things with numbers. but as it turns out, we can do even more: we can use dollar expansions too!
here's a silly clock with magic variables that show the current date and time:
this is probably one of the coolest things i've ever seen in bash. honestly i am a bit horrified that this works at all, but the resulting code is just so simple and elegant. and it feels like i'm just scratching the surface, there's so much potential.
previous: recursive expansions
