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Hands-on Lab·CompTIA Linux+

ACLs and what new files inherit

Owner, group and other is three slots, and a shared directory routinely needs four. This guide grants one user read access and another write access without touching group membership, shows the mask turning a chmod into a change nobody asked for, sets a default ACL and proves what a new file and a new subdirectory inherit - then checks what a copy and an archive keep.

Security Guide 23 of 28 Intermediate

The RPM-family host, which ships the `acl` package. One line of the capture runs on the Debian host to show that it does not.
Server NameIP AddressOSRolesCPURAMHDD
LPLUS-B01192.168.0.74AlmaLinux 10.2RPM-family host - dnf, firewalld, NetworkManager, SELinux2 Core4 GB50 GB

This guide includes

Use this when a second team needs different access to the same directory and adding everyone to one group is the wrong answer. This matters because the mask makes ACLs behave in a way that looks broken, and because a default ACL is the only thing that makes the arrangement survive the next file anyone creates.

Before you start

  1. Where three sets of permission bits run out

  2. One more user, with access the mode bits cannot express

  3. The mask, and why chmod appears to lie

  4. What new files inherit

  5. What survives a copy and an archive

  6. Backing the whole tree up and putting it back

  7. Putting the machine back

Official sources

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