What does this mean:

C:\foo\> icacls .

I think the first one means that userid gets Modify permissions on the directory - which means that user can create files, or update files, or delete files. Right? What is the "NT AUTHORITY\IUSR" user? Is that really a single user ID? Is it the default IIS user ID?

ok, the second line I think refers to a group. It gets the same permissions.

What about all those lines with (I) and (OI) and so on. Please explain.

1 Answer 1


From the Microsoft Article on ICACLS

The entries are users and groups specific to that file (DOMAIN\USER or GROUP), the permissions listed are as follows:

SIDs may be in either numerical or friendly name form. If you use a numerical form, affix the wildcard character * to the beginning of the SID.

icacls preserves the canonical order of ACE (Access Control Entries) entries as:

  • Explicit denials
  • Explicit grants
  • Inherited denials
  • Inherited grants

Perm is a permission mask that can be specified in one of the following forms:

  1. A sequence of simple rights:
  • F (full access)
  • M (modify access)
  • RX (read and execute access)
  • R (read-only access)
  • W (write-only access)
  1. A comma-separated list in parenthesis of specific rights:
  • D (delete)
  • RC (read control)
  • WDAC (write DAC)
  • WO (write owner)
  • S (synchronize)
  • AS (access system security)
  • MA (maximum allowed)
  • GR (generic read)
  • GW (generic write)
  • GE (generic execute)
  • GA (generic all)
  • RD (read data/list directory)
  • WD (write data/add file)
  • AD (append data/add subdirectory)
  • REA (read extended attributes)
  • WEA (write extended attributes)
  • X (execute/traverse)
  • DC (delete child)
  • RA (read attributes)
  • WA (write attributes)

Inheritance rights may precede either Perm form, and they are applied only to directories:

  • (OI): object inherit
  • (CI): container inherit
  • (IO): inherit only
  • (NP): do not propagate inherit
  • (I): permission inherited from parent container

For files, the permission masks are more or less self-explanatory: R means you can read the file, X allows it to be executed (as a program), and so on.

For other kinds of objects, you will have to browse MSDN:

Inheritance rights in English:

  • (I) "Inherited": This ACE was inherited from the parent container.
  • (OI) "Object inherit": This ACE will be inherited by objects placed in this container.
  • (CI) "Container inherit": This ACE will be inherited by subcontainers placed in this container.
  • (IO) "Inherit only": This ACE will be inherited (see OI and CI), but does not apply to this object itself.
  • (NP) "Do not propagate": This ACE will be inherited by objects and subcontainers one level deep – it will not apply to things inside subcontainers.

For the file system, "container" means a folder and "object" means a file, but remember that ACLs can be set on many other kinds of objects, not all of which have a concept of "containers".

  • 1
    thank you. I am google-literate and I can read. But I would like an english explanation of just what it means to have (I)RX. "container inherit" - explain what that means and be specific to the example I provided.
    – Cheeso
    Aug 12, 2011 at 18:35
  • 1
    In that case, you'll need a crash course in NTFS permissions.
    – surfasb
    Aug 12, 2011 at 18:59
  • 1
    If you are google literate, then you can google "ntfs permissions", "ACL" and "File and registry permission." Frankly, to explain every line in laymans terms is essentially re-writing a whole Technet article for you.
    – surfasb
    Aug 12, 2011 at 19:02
  • 4
    One year later... Yes. Much better thank you. As to the others who say: "Go read it", that's what Superuser is for, isn't it? To answer questions that are not clearly answered elsewhere.
    – Cheeso
    Aug 28, 2012 at 1:04
  • 1
    I actually found (I) mentioned in icacls /? on Windows 7. It also had two separate "Delete" rights - (D) was formerly featured in the first list, with (DE) instead in the second list. See ss64.com/nt/icacls.html. It looks like things have changed slightly since then.
    – mwfearnley
    Jul 11, 2017 at 8:04

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