TIL the `until` shell syntax: https://github.com/patte/fly-tailscale-exit/blob/m...

vrosas · on May 25, 2023

Until is great. I use it to remind me if Docker Desktop isn’t running when I try and deploy an app

until docker info > /dev/null 2>&1; do echo ”docker isn’t running…” && sleep 2; done

floodle · on May 25, 2023

How is that different from `while !`?

karatinversion · on May 25, 2023

It's not, except it's a bit nicer to type

abwizz · on May 25, 2023

'until' executes the statement before the condition. while checks the condition first.

should have probably let you find this out for your self.

ykonstant · on May 25, 2023

> 'until' executes the statement before the condition.

This is not the case. From the Open Group Base Specifications Issue 7, 2018 edition, 2.9.4 Compound Commands, The until loop:

    The format of the until loop is as follows:

    until compound-list-1
    do
        compound-list-2
    done

    The compound-list-1 shall be executed, and if it has a zero exit status, the until command completes. Otherwise, the compound-list-2 shall be executed, and the process repeats.

jraph · on May 25, 2023

This is wrong. You must be confusing with the do..while construct we find in some programming languages.

until indeed seems like syntax sugar for while !, I don't think there's a difference.