On Thu, 8 Dec 2005, James Youngman wrote:
> > I am willing to volunteer to look into precisely what merges would be
> > necessary to take their changes.
>
> I suspect we can just take the update as-is. But I would be grateful if
> you could check.
The changes were minimal enough to make a readable patch (as far as
patches go). It is attached.
The more significant differences were:
- update of the definition of "sticky bit" support, removing the mention
of "a" (append-only support) and its respective example.
- addition of a note about ACLs and other controls provided at the file
system by file systems (ext, FFS, mounting read-only),
- removal of the ispell.el LocalWords.
Below are the relevant hunks for the significant changes, and after those
are the word-level changes (using `wdiff')--for those of us who are
extremely detail-oriented.
/a
@@ -69,13 +69,48 @@
@cindex sticky
@cindex swap space, saving text image in
@cindex text image, saving in swap space
[EMAIL PROTECTED] append-only directories
-save the program's text image on the swap device so it will load more
-quickly when run (called the @dfn{sticky bit}). For directories on some
-systems, prevent users from removing files that they do not own in the
-directory; this is called making the directory @dfn{append-only}.
[EMAIL PROTECTED] restricted deletion flag
+prevent users from removing or renaming a file in a directory
+unless they own the file or the directory; this is called the
[EMAIL PROTECTED] deletion flag} for the directory.
+For regular files on some systems, save the program's text image on the
+swap device so it will load more quickly when run; this is called the
[EMAIL PROTECTED] bit}.
@end enumerate
+In addition to the permissions listed above, there may be file attributes
+specific to the file system, e.g: access control lists (ACLs), whether a
+file is compressed, whether a file can be modified (immutability), whether
+a file can be dumped. These are usually set using programs
+specific to the file system. For example:
[EMAIL PROTECTED] should probably say a lot more about ACLs... someday
+
[EMAIL PROTECTED] @asis
[EMAIL PROTECTED] ext2
+On @acronym{GNU} and @acronym{GNU}/Linux the file permissions
+(``attributes'') specific to
+the ext2 file system are set using @command{chattr}.
+
[EMAIL PROTECTED] FFS
+On FreeBSD the file permissions (``flags'') specific to the FFS
+file system are set using @command{chrflags}.
[EMAIL PROTECTED] table
+
+Although a file's permission ``bits'' allow an operation on that file,
+that operation may still fail, because:
+
[EMAIL PROTECTED]
[EMAIL PROTECTED]
+the file-system-specific permissions do not permit it;
+
[EMAIL PROTECTED]
+the file system is mounted as read-only.
[EMAIL PROTECTED] itemize
+
+For example, if the immutable attribute is set on a file,
+it cannot be modified, regardless of the fact that you
+may have just run @code{chmod a+w FILE}.
+
@node Symbolic Modes
@section Symbolic Modes
@@ -252,7 +291,7 @@
@samp{g} in the @var{users} part of the symbolic mode and
@samp{s} in the @var{permissions} part.
-To change a file's permission to stay permanently on the swap device,
-use @samp{o} in the @var{users} part of the symbolic mode and
+To change a file's permission to set the restricted deletion flag or sticky
bit,
+omit the @var{users} part of the symbolic mode (or use @samp{a}) and put
@samp{t} in the @var{permissions} part.
@@ -263,27 +302,16 @@
ug-s
@end example
-To cause a program to be saved on the swap device, you can use
+To set the restricted deletion flag or sticky bit, you can use
the mode:
@example
-o+t
++t
@end example
-
-Remember that the special permissions only affect files that are
-executable, plus, on some systems, directories (on which they have
-different meanings; @pxref{Mode Structure}). Using @samp{a}
-in the @var{users} part of a symbolic mode does not cause the special
-permissions to be affected; thus,
-
[EMAIL PROTECTED]
-a+s
[EMAIL PROTECTED] example
[EMAIL PROTECTED]
-has @emph{no effect}. You must use @samp{u}, @samp{g}, and @samp{o}
-explicitly to affect the special permissions. Also, the
-combinations @samp{u+t}, @samp{g+t}, and @samp{o+s} have no effect.
+The combination @samp{o+s} has no effect. On @acronym{GNU} systems
+the combinations @samp{u+t} and @samp{g+t} have no effect, and
[EMAIL PROTECTED] acts like plain @samp{+t}.
The @samp{=} operator is not very useful with special permissions; for
example, the mode:
@@ -470,7 +497,7 @@
400 Read
Special permissions:
-1000 Save text image on swap device
+1000 Restricted deletion flag or sticky bit
2000 Set group ID on execution
4000 Set user ID on execution
@end example
@@ -478,16 +505,4 @@
For example, numeric mode 4755 corresponds to symbolic mode
@samp{u=rwxs,go=rx}, and numeric mode 664 corresponds to symbolic mode
@samp{ug=rw,o=r}. Numeric mode 0 corresponds to symbolic mode
[EMAIL PROTECTED]
-
[EMAIL PROTECTED] texi related words used by Emacs' spell checker ispell.el
-
[EMAIL PROTECTED] LocalWords: texinfo setfilename settitle setchapternewpage
[EMAIL PROTECTED] LocalWords: iftex finalout ifinfo DIR titlepage vskip pt
[EMAIL PROTECTED] LocalWords: filll dir samp dfn noindent xref pxref
[EMAIL PROTECTED] LocalWords: var deffn texi deffnx itemx emph asis
[EMAIL PROTECTED] LocalWords: findex smallexample subsubsection cindex
-
[EMAIL PROTECTED] LocalWords: chgrp chown executability filesystem FIXME ls og
rw
[EMAIL PROTECTED] LocalWords: rwx rwxr rwxs rwxXstugo rx rX rxw setgid setuid ug
[EMAIL PROTECTED] LocalWords: ugo ugoa umask
[EMAIL PROTECTED]
Here are the word-level changes in their context (line numbers are
approximate) that are unmentioned by the hunks above:
@@ -46,9 +46,11 @@
Files are given an owner and group when they are created. Usually the
owner is the current user and the group is the group of the directory
the file is in, but this varies with the operating system, the
[-filesystem-]
{+file system+} the file is created on, and the way the file is created. You
can change the owner and group of a file by using the [EMAIL PROTECTED] [EMAIL
PROTECTED] and
[EMAIL PROTECTED]
[EMAIL PROTECTED] commands.
In addition to the three sets of three permissions listed above, a
file's permissions have three special components, which affect only
@@ -57,11 +59,13 @@
@enumerate
@item
@cindex setuid
[-set-]
{+Set+} the process's effective user ID to that of the file upon execution
(called the @dfn{setuid bit}). No effect on directories.
@item
@cindex setgid
[-set-]
{+Set+} the process's effective group ID to that of the file upon execution
(called the @dfn{setgid bit}). For directories on some systems, put
files created in the directory into the same group as the directory, no
matter what group the user who creates them is in.
@@ -89,9 +130,14 @@
The format of symbolic modes is:
@example
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL
PROTECTED]@r{][},@[EMAIL PROTECTED]
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL
PROTECTED],@[EMAIL PROTECTED]
@end example
[EMAIL PROTECTED]
where @var{perms} is either zero or more letters from the set
@samp{rwxXst}, or a single letter from the set @samp{ugo}.+}
The following sections describe the operators and other details of
symbolic modes.
@@ -118,7 +164,7 @@
@noindent
The spaces between the three parts above are shown for readability only;
symbolic modes [-can not-] {+cannot+} contain spaces.
The @var{users} part tells which users' access to the file is changed.
It consists of one or more of the following letters (or it can be empty;
@@ -160,7 +206,7 @@
@end table
The @var{permissions} part tells what kind of access to the file should
be changed; it is {+normally+} zero or more of the following letters. As with
the
@var{users} part, the order does not matter when more than one letter is
given. Omitting the @var{permissions} part is useful only with the
@samp{=} operation, where it gives the specified @var{users} no access
@@ -185,7 +231,7 @@
a=rw
@end example
To remove write permission for [-from-] all users other than the file's
owner, use:
@example
@@ -209,7 +255,8 @@
Another way to specify the same thing is:
@example
[-og-rxw-]
{+og-rwx+}
@end example
@node Copying Permissions
@@ -217,17 +264,18 @@
@cindex copying existing permissions
@cindex permissions, copying existing
You can base [-part of-] a file's permissions on [-part of-] its existing
permissions. To do
this, instead of using {+a series of+} @samp{r}, @samp{w}, or @samp{x}
{+letters+} after the
operator, you use the letter @samp{u}, @samp{g}, or @samp{o}. For
example, the mode
@example
o+g
@end example
@noindent
[EMAIL PROTECTED] FIXME describe the ls -l notation for showing permissions.-]
adds the permissions for users who are in a file's group to the
permissions that other users have for the file. Thus, if the file
started out as mode 664 (@samp{rw-rw-r--}), the above mode would change
@@ -252,11 +300,13 @@
@samp{t} in the @var{permissions} part.
For example, to add [-set user ID-] {+set-user-ID+} permission to a program,
you can use the mode:
@example
u+s
@end example
To remove both [-set user ID-] {+set-user-ID+} and [-set group ID-]
{+set-group-ID+} permission from
it, you can use the mode:
@example
@@ -263,5 +313,7 @@
the mode:
@example
[-o+t-]
{++t+}
@end example
@@ -300,6 +352,7 @@
@end example
@noindent
does [-cause the file to be saved on-] {+set+} the [-swap device,-]
{+restricted deletion flag or sticky bit,+} but it also
removes all read, write, and execute permissions that users not in the
file's group might have had for it.
@@ -310,9 +362,8 @@
@cindex conditional executability
There is one more special type of symbolic permission: if you use
@samp{X} instead of @samp{x}, execute permission is affected only if the
file [-already had execute permission or-] is a [-directory. It affects
directories' execute permission even if they did not initially have any-]
{+directory or already had+} execute [-permissions set.-] {+permission.+}
For example, this mode:
@@ -321,8 +372,8 @@
@end example
@noindent
gives all users permission to {+search directories, or to+} execute files
[-(or search directories)-] if
anyone could {+execute them+} before.
@node Multiple Changes
@subsection Making Multiple Changes
@@ -345,7 +396,7 @@
gives users other than the owner of the file read permission and, if
it is a directory or if someone already had execute permission
to it, gives them execute permission; and it also denies them write
permission to [-it-] {+the+} file. It does not affect the permission that the
owner of the file has for it. The above mode is equivalent to
the two modes:
@@ -433,22 +484,25 @@
@cindex numeric modes
@cindex file permissions, numeric
@cindex octal numbers for file modes
[-File permissions are stored internally as 16 bit integers.-]
As an
alternative to giving a symbolic mode, you can give an octal (base 8)
number that [-corresponds to the internal representation of-] {+represents+}
the new mode.
This number is always interpreted in octal; you do not have to add a
leading 0, as you do in C. Mode 0055 is the same as mode 55.
A numeric mode is usually shorter than the corresponding symbolic
mode, but it is limited in that it [-can not-] {+cannot+} take into account a
file's
previous permissions; it can only set them absolutely.
The permissions granted to the user,
to other users in the file's group,
and to other users not in the file's group [-are-] each [-stored as-]
{+require+} three
bits, which are represented as one octal digit. The three special
permissions [-are-] also [-each stored as-] {+require+} one [-bit,-] {+bit
each,+} and they are as a group
represented as another octal digit. Here is how the bits are [-arranged
in the 16 bit integer,-] {+arranged,+}
starting with the lowest valued bit:
@example
Value in Corresponding
@@ -478,3 +532,5 @@
For example, numeric mode 4755 corresponds to symbolic mode
@samp{u=rwxs,go=rx}, and numeric mode 664 corresponds to symbolic mode
@samp{ug=rw,o=r}. Numeric mode 0 corresponds to symbolic mode
[EMAIL PROTECTED]
[EMAIL PROTECTED]--- perm.texi 12 Apr 2000 06:16:53 -0400 1.2
+++ perm.texi 08 Dec 2005 11:54:35 -0500
@@ -46,9 +46,9 @@
Files are given an owner and group when they are created. Usually the
owner is the current user and the group is the group of the directory
the file is in, but this varies with the operating system, the
-filesystem the file is created on, and the way the file is created. You
-can change the owner and group of a file by using the @code{chown} and
[EMAIL PROTECTED] commands.
+file system the file is created on, and the way the file is created. You
+can change the owner and group of a file by using the @command{chown} and
[EMAIL PROTECTED] commands.
In addition to the three sets of three permissions listed above, a
file's permissions have three special components, which affect only
@@ -57,11 +57,11 @@
@enumerate
@item
@cindex setuid
-set the process's effective user ID to that of the file upon execution
+Set the process's effective user ID to that of the file upon execution
(called the @dfn{setuid bit}). No effect on directories.
@item
@cindex setgid
-set the process's effective group ID to that of the file upon execution
+Set the process's effective group ID to that of the file upon execution
(called the @dfn{setgid bit}). For directories on some systems, put
files created in the directory into the same group as the directory, no
matter what group the user who creates them is in.
@@ -69,13 +69,48 @@
@cindex sticky
@cindex swap space, saving text image in
@cindex text image, saving in swap space
[EMAIL PROTECTED] append-only directories
-save the program's text image on the swap device so it will load more
-quickly when run (called the @dfn{sticky bit}). For directories on some
-systems, prevent users from removing files that they do not own in the
-directory; this is called making the directory @dfn{append-only}.
[EMAIL PROTECTED] restricted deletion flag
+prevent users from removing or renaming a file in a directory
+unless they own the file or the directory; this is called the
[EMAIL PROTECTED] deletion flag} for the directory.
+For regular files on some systems, save the program's text image on the
+swap device so it will load more quickly when run; this is called the
[EMAIL PROTECTED] bit}.
@end enumerate
+In addition to the permissions listed above, there may be file attributes
+specific to the file system, e.g: access control lists (ACLs), whether a
+file is compressed, whether a file can be modified (immutability), whether
+a file can be dumped. These are usually set using programs
+specific to the file system. For example:
[EMAIL PROTECTED] should probably say a lot more about ACLs... someday
+
[EMAIL PROTECTED] @asis
[EMAIL PROTECTED] ext2
+On @acronym{GNU} and @acronym{GNU}/Linux the file permissions
+(``attributes'') specific to
+the ext2 file system are set using @command{chattr}.
+
[EMAIL PROTECTED] FFS
+On FreeBSD the file permissions (``flags'') specific to the FFS
+file system are set using @command{chrflags}.
[EMAIL PROTECTED] table
+
+Although a file's permission ``bits'' allow an operation on that file,
+that operation may still fail, because:
+
[EMAIL PROTECTED]
[EMAIL PROTECTED]
+the file-system-specific permissions do not permit it;
+
[EMAIL PROTECTED]
+the file system is mounted as read-only.
[EMAIL PROTECTED] itemize
+
+For example, if the immutable attribute is set on a file,
+it cannot be modified, regardless of the fact that you
+may have just run @code{chmod a+w FILE}.
+
@node Symbolic Modes
@section Symbolic Modes
@@ -89,9 +124,13 @@
The format of symbolic modes is:
@example
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL
PROTECTED]@r{][},@[EMAIL PROTECTED]
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED],@[EMAIL
PROTECTED]
@end example
[EMAIL PROTECTED]
+where @var{perms} is either zero or more letters from the set
[EMAIL PROTECTED], or a single letter from the set @samp{ugo}.
+
The following sections describe the operators and other details of
symbolic modes.
@@ -118,7 +157,7 @@
@noindent
The spaces between the three parts above are shown for readability only;
-symbolic modes can not contain spaces.
+symbolic modes cannot contain spaces.
The @var{users} part tells which users' access to the file is changed.
It consists of one or more of the following letters (or it can be empty;
@@ -160,7 +199,7 @@
@end table
The @var{permissions} part tells what kind of access to the file should
-be changed; it is zero or more of the following letters. As with the
+be changed; it is normally zero or more of the following letters. As with the
@var{users} part, the order does not matter when more than one letter is
given. Omitting the @var{permissions} part is useful only with the
@samp{=} operation, where it gives the specified @var{users} no access
@@ -185,7 +224,7 @@
a=rw
@end example
-To remove write permission for from all users other than the file's
+To remove write permission for all users other than the file's
owner, use:
@example
@@ -209,7 +248,7 @@
Another way to specify the same thing is:
@example
-og-rxw
+og-rwx
@end example
@node Copying Permissions
@@ -217,17 +256,17 @@
@cindex copying existing permissions
@cindex permissions, copying existing
-You can base part of a file's permissions on part of its existing
-permissions. To do this, instead of using @samp{r}, @samp{w}, or
[EMAIL PROTECTED] after the operator, you use the letter @samp{u}, @samp{g}, or
[EMAIL PROTECTED] For example, the mode
+You can base a file's permissions on its existing permissions. To do
+this, instead of using a series of @samp{r}, @samp{w}, or @samp{x}
+letters after the
+operator, you use the letter @samp{u}, @samp{g}, or @samp{o}. For
+example, the mode
@example
o+g
@end example
@noindent
[EMAIL PROTECTED] FIXME describe the ls -l notation for showing permissions.
adds the permissions for users who are in a file's group to the
permissions that other users have for the file. Thus, if the file
started out as mode 664 (@samp{rw-rw-r--}), the above mode would change
@@ -252,45 +291,34 @@
@samp{g} in the @var{users} part of the symbolic mode and
@samp{s} in the @var{permissions} part.
-To change a file's permission to stay permanently on the swap device,
-use @samp{o} in the @var{users} part of the symbolic mode and
+To change a file's permission to set the restricted deletion flag or sticky
bit,
+omit the @var{users} part of the symbolic mode (or use @samp{a}) and put
@samp{t} in the @var{permissions} part.
-For example, to add set user ID permission to a program,
+For example, to add set-user-ID permission to a program,
you can use the mode:
@example
u+s
@end example
-To remove both set user ID and set group ID permission from
+To remove both set-user-ID and set-group-ID permission from
it, you can use the mode:
@example
ug-s
@end example
-To cause a program to be saved on the swap device, you can use
+To set the restricted deletion flag or sticky bit, you can use
the mode:
@example
-o+t
[EMAIL PROTECTED] example
-
-Remember that the special permissions only affect files that are
-executable, plus, on some systems, directories (on which they have
-different meanings; @pxref{Mode Structure}). Using @samp{a}
-in the @var{users} part of a symbolic mode does not cause the special
-permissions to be affected; thus,
-
[EMAIL PROTECTED]
-a+s
++t
@end example
[EMAIL PROTECTED]
-has @emph{no effect}. You must use @samp{u}, @samp{g}, and @samp{o}
-explicitly to affect the special permissions. Also, the
-combinations @samp{u+t}, @samp{g+t}, and @samp{o+s} have no effect.
+The combination @samp{o+s} has no effect. On @acronym{GNU} systems
+the combinations @samp{u+t} and @samp{g+t} have no effect, and
[EMAIL PROTECTED] acts like plain @samp{+t}.
The @samp{=} operator is not very useful with special permissions; for
example, the mode:
@@ -300,7 +328,7 @@
@end example
@noindent
-does cause the file to be saved on the swap device, but it also
+does set the restricted deletion flag or sticky bit, but it also
removes all read, write, and execute permissions that users not in the
file's group might have had for it.
@@ -310,9 +338,7 @@
@cindex conditional executability
There is one more special type of symbolic permission: if you use
@samp{X} instead of @samp{x}, execute permission is affected only if the
-file already had execute permission or is a directory. It affects
-directories' execute permission even if they did not initially have any
-execute permissions set.
+file is a directory or already had execute permission.
For example, this mode:
@@ -321,8 +347,8 @@
@end example
@noindent
-gives all users permission to execute files (or search directories) if
-anyone could before.
+gives all users permission to search directories, or to execute files if
+anyone could execute them before.
@node Multiple Changes
@subsection Making Multiple Changes
@@ -345,7 +371,7 @@
gives users other than the owner of the file read permission and, if
it is a directory or if someone already had execute permission
to it, gives them execute permission; and it also denies them write
-permission to it file. It does not affect the permission that the
+permission to the file. It does not affect the permission that the
owner of the file has for it. The above mode is equivalent to
the two modes:
@@ -433,22 +459,23 @@
@cindex numeric modes
@cindex file permissions, numeric
@cindex octal numbers for file modes
-File permissions are stored internally as 16 bit integers. As an
+As an
alternative to giving a symbolic mode, you can give an octal (base 8)
-number that corresponds to the internal representation of the new mode.
+number that represents the new mode.
This number is always interpreted in octal; you do not have to add a
leading 0, as you do in C. Mode 0055 is the same as mode 55.
A numeric mode is usually shorter than the corresponding symbolic
-mode, but it is limited in that it can not take into account a file's
+mode, but it is limited in that it cannot take into account a file's
previous permissions; it can only set them absolutely.
-The permissions granted to the user, to other users in the file's group,
-and to other users not in the file's group are each stored as three
+The permissions granted to the user,
+to other users in the file's group,
+and to other users not in the file's group each require three
bits, which are represented as one octal digit. The three special
-permissions are also each stored as one bit, and they are as a group
-represented as another octal digit. Here is how the bits are arranged
-in the 16 bit integer, starting with the lowest valued bit:
+permissions also require one bit each, and they are as a group
+represented as another octal digit. Here is how the bits are arranged,
+starting with the lowest valued bit:
@example
Value in Corresponding
@@ -470,7 +497,7 @@
400 Read
Special permissions:
-1000 Save text image on swap device
+1000 Restricted deletion flag or sticky bit
2000 Set group ID on execution
4000 Set user ID on execution
@end example
@@ -478,16 +505,4 @@
For example, numeric mode 4755 corresponds to symbolic mode
@samp{u=rwxs,go=rx}, and numeric mode 664 corresponds to symbolic mode
@samp{ug=rw,o=r}. Numeric mode 0 corresponds to symbolic mode
[EMAIL PROTECTED]
-
[EMAIL PROTECTED] texi related words used by Emacs' spell checker ispell.el
-
[EMAIL PROTECTED] LocalWords: texinfo setfilename settitle setchapternewpage
[EMAIL PROTECTED] LocalWords: iftex finalout ifinfo DIR titlepage vskip pt
[EMAIL PROTECTED] LocalWords: filll dir samp dfn noindent xref pxref
[EMAIL PROTECTED] LocalWords: var deffn texi deffnx itemx emph asis
[EMAIL PROTECTED] LocalWords: findex smallexample subsubsection cindex
-
[EMAIL PROTECTED] LocalWords: chgrp chown executability filesystem FIXME ls og
rw
[EMAIL PROTECTED] LocalWords: rwx rwxr rwxs rwxXstugo rx rX rxw setgid setuid ug
[EMAIL PROTECTED] LocalWords: ugo ugoa umask
[EMAIL PROTECTED]
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