if you are not able to do upgrade then easiest way is encrypt what you need into Base64. I't not secure, but if you encrypt whole line(s) of code then it will not be interesting for someone encrypting everything what can be seen.
Another option what I see is calling file system script to which normal user don't have access.
With calling script I mean this: https://confluence.atlassian.com/bamboo/script-289277046.html
You can use one of them - variable or encrypted code in scripts.
About encrypting whole line you can inspire for example here: https://linuxhint.com/bash_base64_encode_decode/
So you will encode to Base64 when you will programming script and inside os script you will decrypt it.
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