Susan PotterNov 2, 2022

Today I needed a simple lightweight way to interpolate environment variables into a template without installing heavyweight dependencies (CI/CD) and I remembered envsubst (only 1.45 MiB expanded in Nix)!

echo "Hello user ${USER} in ${HOME}. It's time to say ${HELLO}!" > welcome.tmpl

env HELLO="willkommen" envsubst < welcome.tmpl
Hello user xxxx in /home/xxxx. It's time to say willkommen!

Show threadPuercoPopNov 2, 2022
I've seen envsubsts be used to parameterize xml configs from shell scripts. Not horrible.
Show threadSusan Potter
@PuercoPop if you needed to do a lot more and could add bigger dependencies I would use a full blown config/templating language but for the small cases like posting custom JSON to Slack webhooks after a CI/CD job succeeded/fails.
Nov 2, 2022 at 11:38pmWeb