setfacl

Set file access control lists

high risk

interactive breakdown — edit the command and press Explain
$ 
⚠ Risks & cautions
Safer / dry-run alternatives
getfacl -R <path> > acl.bakBack up current ACLs
setfacl --restore=acl.bakRestore them if needed
What it does

Adds, modifies or removes ACL entries. Use for fine-grained sharing without changing groups.

Common flags
FlagMeaning
-mModify ACL entries
-xRemove entries
-bRemove all ACLs
-RRecurse
-dSet default ACL for new files
Examples
setfacl -m u:alice:rwX /srv/sharedGrant alice access · explain & risk-check →
setfacl -R -m g:dev:rX /srv/appRecursive read access for a group · explain & risk-check →
Related
getfacl chmod chown
Open the full explainer →More in Files & Archives

Reference text is hand-written and may be incomplete — check man setfacl for your version. Test destructive commands on a non-production system first.