#!/bin/bash
s='2020-11-17 15:34:04.208 -0500 Information 94 XYZ-ASDF-FMP123 Client "%USERNAME% (QWER-L1212-W6) [11.22.333.44]" opening database "databasename" as "username".'
grep -o '([^()]*) \[[^][]*]' <<< "$s" | sort -u
IyEvYmluL2Jhc2gKcz0nMjAyMC0xMS0xNyAxNTozNDowNC4yMDggLTA1MDAgSW5mb3JtYXRpb24gOTQgIFhZWi1BU0RGLUZNUDEyMyAgQ2xpZW50ICIlVVNFUk5BTUUlIChRV0VSLUwxMjEyLVc2KSBbMTEuMjIuMzMzLjQ0XSIgb3BlbmluZyBkYXRhYmFzZSAiZGF0YWJhc2VuYW1lIiBhcyAidXNlcm5hbWUiLicKZ3JlcCAtbyAnKFteKCldKikgXFtbXl1bXSpdJyA8PDwgIiRzIiB8IHNvcnQgLXU=