On 2020-08-06 20:33, Greg Wooledge wrote:
For short strings, doing this sort of parsing in bash is fine. But as you can see, on large inputs, it does not scale well. The fact that each iteration makes a *copy* of nearly the entire remaining input doesn't help matters, either -- right off the bat, that algorithm makes the run time explode, even before you take into account bash's 100% interpreted runtime slowness.
Thanks for the insights.So, re: the OP's question, it's possible in bash, but there's unlikely to be an efficient way for long strings.
But (unwilling to give up) IF it can be guaranteed that the string will never contain newlines, then this is about 16x faster than the snip-and-loop version:
---
#!/bin/bash
_S=' 34 + 45 \| abc \| 1 2 3 \| c\|123abc '
del='\|'
mapfile -t arr <<< ${_S//"${del}"/$'\n'}
declare -p arr
---
Seems to accept unusual characters and empty items.
Awk can ignore newlines, but a lot of the other shell tools are
line-based anyway.
-- John