$USER is not set in cron

[do-community]

$USER is not set in cron

[imchairmanm]

Hey there. I'm unable to reproduce your issue here unfortunately (but I agree with you anyways).

Since the cron script is using sudo -u backup, all of the environmental variables typically set by sudo are applied when running the backup-mysql.sh script. You can find a list of those in the "ENVIRONMENT" section of man sudo (USER is one of them). You can validate this by adding a printenv to the /usr/local/bin/backup-mysql.sh script itself:

#!/bin/bash

export LC_ALL=c

# print the current environment
printenv > /tmp/scriptenv
. . .

At least on the systems I've tested, /tmp/scriptenv has USER=backup as expected.

All that being said, I think you're right that it'd be better to use id --user --name to get the user since it seems more reliable. I don't think it matters in this specific instance, but it seems like good practice anyways. I'm going to close this one and accept your PR. Thanks for the heads up!