diff --git a/knowledge base/acl.md b/knowledge base/acl.md
index cb32301..a6bb238 100644
--- a/knowledge base/acl.md	
+++ b/knowledge base/acl.md	
@@ -17,9 +17,10 @@ BSD systems use NFSv4 ACLs by default in ZFS.
 List of **NFSv4** [permission tags][syntax descriptions for setting acls] and [inheritance options][acl inheritance].
 
 ```sh
-# Install the tool.
+# Install the tools.
 apt install 'acl'
 dnf install 'acl'
+zypper install 'acl'
 
 # Show ACLs.
 getfacl 'path/to/file'
@@ -127,11 +128,15 @@ setfacl -a '5' 'everyone@:r-x---a-R-c---:-d-----:allow' 'path/to/dir'
 - [`setfacl` FreeBSD manual page][setfacl freebsd manual page]
 - [Syntax descriptions for setting ACLs]
 - [ACL inheritance]
+- [`chmod`][chmod] for how to force new files to be owned by specific users or groups
 
 <!--
   References
   -->
 
+<!-- Knowledge base -->
+[chmod]: chmod.md
+
 <!-- Others -->
 [access control lists (acl) in linux]: https://www.geeksforgeeks.org/access-control-listsacl-linux/
 [acl inheritance]: https://docs.oracle.com/cd/E19253-01/819-5461/gbaax/index.html
diff --git a/knowledge base/chmod.md b/knowledge base/chmod.md
index 8034553..687851c 100644
--- a/knowledge base/chmod.md	
+++ b/knowledge base/chmod.md	
@@ -9,10 +9,12 @@ chmod 'u=rw' "path/to/dir"
 chmod 'go+x' "path/to/file"
 
 # Set 'setuid' bit.
+# Set on directories, forces new files to be owned by the same user by default.
 chmod '04755' "path/to/dir"
 chmod 'u-s' "path/to/file"
 
 # Set 'setgid' bit.
+# Set on directories, forces new files to be owned by the same group by default.
 chmod '02775' "path/to/dir"
 chmod 'g+s' "path/to/file"