Sysadmin

ACLs for log‑only access

When you need a user to read system logs but you don’t want to give them sudo or pull them into a privileged group, POSIX ACLs are the cleanest way to do it.
They let you hand out read rights on a per‑file or per‑directory basis, and you can set defaults so that every new file inherits the same restrictions.

A backup account that pulls logs to an off‑site archive but never touches the live system is the classic case. ACLs keep the principle of least privilege intact while still letting the job run unattended.

Why ACLs instead of changing ownership?

When a web server runs as www-data and the dev squad needs to touch files in /var/www/html, the quick fix is usually chgrp the directory and slap a write bit on the group. That swaps the group ownership, which can trip up services that expect the original group or automated deploy scripts that hard‑code the owner. ACLs let you hand out the right permissions without touching the classic ownership columns.