Content-type: text/html Man page of setacl

setacl

Section: User Commands (1)
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NAME

setacl - Changes the access control list on a file or directory (ACL)  

SYNOPSIS

setacl [-a] [-b] [-k] [-K]
       [-b] [-d -D] [-x entries] 
       [-X file1] [-u entries]
       [-U file2] filename ...  

FLAGS

Specifies access ACL. Reset the ACL to just the base entries (u::, g::, o::). The operation applies to the default access ACL. Default ACLs must contain at least the 3 base entries (the entries that correspond to the permission bits). When you first create a default ACL, if you do not specify these 3 entries they default to the current value of the 3 base entries (or permission bits) of the directory's access ACL. You should specify values for the 3 base entries if the current value in the access ACL is not appropriate.

The -d flag is not defined by POSIX. The operation applies to the default directory ACL. Default ACLs must contain at least the 3 base entries (the entries that correspond to the permission bits). When you first create a default ACL, if you do not specify these 3 entries they default to the current value of the 3 base entries (or permission bits) of the directory's access ACL. You should specify values for the 3 base entries if the current value in the access ACL is not appropriate.

The -D flag is not defined by POSIX. Delete the default access ACL for the designated directory. Delete the default directory ACL for the designated directory. The -K flag is not defined by POSIX. Removes the ACL entries designated in file1 from the designated object. Removes the designated entries in the ACL from the designated object. Updates the ACL with the specified entries that match existing entries in tag type and tag qualifier. ACL entries are added if they are not already present in the ACL. See the Contents of an ACL Entry section for the format of ACL entries. Updates the ACL with the entries specified in file2 that match existing entries in tag type and tag qualifier. ACL entries are added if they are not already present in the ACL. See the Contents of an ACL Entry section for the format of ACL entries.

The -a, -d, and -D flags are not mutually exclusive; they can all be specified, and all are set. If none are specified the -a flag is assumed. The -d and -D flags only apply to directories.

The -b flag is applied before any of the -u, -U, -x, or -X flags

Multiple -u, -U, -x, and -X flags are all applied to the acl in the order listed on the command line. All of flags are applied to a temporary copy of the ACL before the ACL is applied to the files. It is not an error for an intermediate version of the ACL to be ill formed, as long as the ACL is well formed by the time it is applied.

Several flags accept arguments of the following types: The ACL entries used to perform the requested operation. Multiple ACL entries are separated by commas. There is no required ordering of entries. A file containing ACL entries to use to perform the requested operation. Each entry should be on a separate line. There is no required ordering of entries. If a line contains the comment character, #, setacl ignores the line.  

DESCRIPTION

This command is based on Draft 13 of the POSIX P1003.6 standard. The command may change as the P1003.6 standard is finalized. The setacl command sets the access control list (ACL) to the designated list of objects, which can be one or more files or directories.

 

Contents of an ACL Entry

The external representation of an ACL entry consists of three colon (:) separated fields. The first field is a tag type, the second field contains optional qualifiers whose meaning depend on the tag type, and the third field is a list of the permissions. The following examples are typical: user::rwx user:jdoe:rw- user:mightymouse:r-- user:bsmith:rwx group::r-- other::--- The tag types and associated qualifiers are: If the qualifier field is empty, the entry defines the permissions of the user who owns the file or directory. User names or UIDs can be specified as qualifiers; in this case, the entry defines the permissions of these users. If the qualifier field is empty, the entry defines the permissions of users who are members of the group associated with the file or directory. Group names or GIDs can be specified as qualifiers; in this case the entry defines the permissions of members of these groups. No qualifiers are allowed for the other tag type. This entry specifies the permissions for users who are not covered by any other entries.

The third field specifies the discretionary access permissions. They are:

Letter        Octal   PERMISSION
r       4       Read access
w       2       Write access
x       1       Execute/Search access
-       0       No access
A set of permissions in an ACL entry is internally represented in three bits and displayed as a character string, as in untrusted Tru64 UNIX.

The set of permissions can be specified in three ways: As an octal digit. Add the numbers shown above to determine the permissions. The value 0 (zero), for example, specifies no permissions, and the value 7 specifies all permissions. As an absolute character string. An absolute character string contains three characters. The first specifies read permission, the second write permission, and the third specifies execute/search permission. To grant all permissions, specify rwx in that order. To deny one or more permissions, use the character - in the appropriate positions. For example, the entry r-x grants read and execute/search permissions and denies write permission. As a relative character string. A relative character string adds or removes permissions from the existing set. To add permissions, specify a "+" followed by one or more permission letters. For example, +r adds read permission to the existing set. To remove permissions, specify a "^" followed by one or more permission letters. For example, ^x removes execute/search permission.

Both octal digits and absolute character strings set the permissions to the specified values. One of these forms should be used for new entries.

Relative permissions update an existing ACL entry (flags -u and -U) with an input entry that matches in tag type and tag qualifier. If setacl adds an entry to an ACL, a + prefix is ignored and the set of permissions is entered as an absolute string; if the prefix is ^, the permissions field is set to no access. If an entry is to be removed from an ACL, input permissions are ignored altogether.

Suppose an ACL entry is specified with relative permissions, group:dec:^wx (remove wx permissions) to be applied to a matching entry with permissions r-x. The matching entry will have a new set of permissions as follows: group:dec:r-- (read only)  

Contents of an ACL

An ACL contains at least three entries: A user entry with no qualifiers A group entry with no qualifiers An other entry

An ACL also has one or more user or group entries with qualifiers.

user::rwx
group::rw-
user:user1:r-x
group:dec:--x

other::rwx

The entry group::rw- is the file group owner and specifies the read and write permissions.  

DEFAULT ACLs

The default directory ACL allows the owner or a privileged user to associate an ACL with a directory that is to be inherited as an access ACL when a subdirectory is created. The default directory ACL will also be inherited as the default directory ACL by the new directory.

The default access ACL allows the owner or a privileged user to associate an ACL with a directory that is to be inherited as an access ACL when an object is created within the directory. If the object being created is a directory and a default directory ACL exists on the parent directory, it is inherited as the access ACL and not the default access ACL. The default access ACL is inherited as the default access ACL for any subdirectory created

Like access ACLs, both default directory ACLs and default access ACLs must contain at a minimum the 3 base entries that equate to the permission bits (user::, group::, other::).  

AUTHORIZATIONS

To change or remove the ACL of a file, the user must either own the file or be privileged.  

EXAMPLES

Assume that the ACL on a file named shared contains the following minimum entries:

user::rwx group::r-x other::---

The following command updates and adds entries:

$ setacl -u group::r--,user:alpha:-w- shared

The resulting ACL entries are:

user::rwx user:alpha:-w- group::r-- other::---

The owning group entry on the command line matches the existing group entry, so the permission set is reduced to read only. The user entry on the command line does not match an existing entry and is added. Assume that the ACL on a file named shared contains the following entries:

user::rwx user:user1:-w- group::-w- group:dec:-wx other::---

Apply the setacl -u command (update) to the shared file as follows:

$ setacl -u user:user1:-wx shared

The resulting ACL entries are: user::rwx user:user1:-wx- group::-w- group:dec:-wx other::--- Assume that the directory foo contains no default ACLs, and the following command is issued:

$ setacl -d -u user::rw-,group::r--,other::r--,user:dec:rw- foo

Any file or directory that is created within the directory foo now inherits the following ACL as the access ACL:

user::rw- user:dec:r-- group::r-- other::r-- Assume that the directory foo contains no default ACLs, and the following command is issued:

$ setacl -D -u user::rwx,group::r-x,other::---,user:dec:r-x foo

Any directory that is created within the directory foo now inherits the following ACL as the access ACL, as well as its default directory ACL:

user::rwx user:dec:r-x group::r-x other::--- Assume that the directory foo contains no default ACLs, the 3 base entries of the access ACL on directory foo are u::rwx, group::r-x, other::r-x, and the following commands are issued:

$ setacl -D -u user:dec:r-- foo $ setacl -d -u user::rw-,group::r--,other::---,user:alpha:r-- foo

Any directory that is created within the directory foo now inherits the default directory ACL of foo as its access ACL as well as its default directory ACL:

user::rwx user:dec:r-- group::r-x other::r-x

In addition, any directory that is created within the directory foo inherits the default access ACL of foo as its default access ACL:

user::rw- user:alpha:r-- group::r-- other::r--

Any file created in directory foo inherits the default access ACL of foo as its access ACL:

user::rw- user:alpha:r-- group::r-- other::r--  

EXIT VALUES

If setacl is invoked incorrectly or cannot decipher the specified ACL, it returns an exit status of 1. setacl returns an exit status of 0 (zero) if all files are changed.  

ERRORS

The setacl command displays an error message explaining why an ACL of a file could not be changed.  

RELATED INFORMATION

Commands: getacl(1)

Files: acl(4)

Security delim off


 

Index

NAME
SYNOPSIS
FLAGS
DESCRIPTION
Contents of an ACL Entry
Contents of an ACL
DEFAULT ACLs
AUTHORIZATIONS
EXAMPLES
EXIT VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:42:57 GMT, October 02, 2010