RH124 Ch 7: Diagnose Permission Problems

The audit team reports "Permission denied" errors. User `kiran` (group `audit`) cannot read the Q3 report, nobody can run the backup check script, and student's new files are too open. Fix each problem with the least access needed.

Tasks

1. kiran must be able to read /srv/reports/q3.txt through group audit, while users outside audit get no access to the directory or the file.
2. Members of audit must also be able to create files in /srv/reports, but must not be able to delete files owned by others.
3. Every user must be able to run /usr/local/bin/backup-check, but only root may change it.
4. Set student's default umask to 027 permanently, so new files are not readable by others.