Editing File-system permissions (section)

===Operations===
The operations that can be granted or denied include:
* ''Read'' grants the ability to read a file. When set for a directory, this permission grants the ability to read the names of contained files, but not to read other information about them such as contents, file type, size, ownership, permissions.
* ''Write'' grants the ability to modify a file. When set for a directory, this permission grants the ability to modify entries in the directory, which includes creating, deleting and renaming files. This requires that ''execute'' is also set; without it, the write permission is meaningless for directories.
* ''Execute'' grants the ability to execute a file. This permission must be set for executable programs to allow running them. When set for a directory, this permission is interpreted as the ''search'' permission {{endash}} granting the ability to access file contents and metadata if its name is known, but not list files in the directory, unless ''read'' is set also.

The effect of setting the permissions on a directory, rather than a file, is "one of the most frequently misunderstood file permission issues".<ref>{{cite web |last=Hatch |first=Bri |url=http://www.hackinglinuxexposed.com/articles/20030424.html |title=Linux File Permission Confusion pt 2 |website=Hacking Linux Exposed |date=April 24, 2003 |access-date=July 6, 2011}}</ref>

Unlike ACL-based systems, these permissions are not inherited. Files created within a directory do not necessarily have the same permissions as its containing directory.