How to test that a variable starts with a string in bash?

Question

For a fixed prefix length I can do it like so:

[ a${filename:0:2} = a.# ] && echo temporary emacs file

How to do it for an arbitrary prefix?

Is there a cleaner way?

question from:https://stackoverflow.com/questions/4132510/how-to-test-that-a-variable-starts-with-a-string-in-bash

Answer 1

[['s = operator takes a pattern in the right operand.

var=123
[[ 1234 = $var* ]] && ...