At 09:04 AM 12/12/01 +0100, Richard Swartz wrote the following:
>quite a while back, on another list(HELPNET, ACCMAIL?) you posted a nice
>explanation about how the Unix file permissions result in the three digit
>octal
>notation we see in attached files (beg*n 666 example.zip). I thought I had
>saved your post, but as chance had it, I was asked yesterday how it works, and
>I couldn't find it. I guess it was lost in the last great data migration. Do
>you happen to still have the original post or could you explain it again? :)
This is the result of a "dir" command at an ftp site.
----------------------------------------------------------------------------
----
total 12
-rw-r--r-- 1 root wheel 480 May 1 16:59 RATECARD.TXT
-rw-rw-r-- 1 root wheel 696 Nov 19 1997 README
-rw-r--r-- 1 root wheel 3344 Sep 1 2000 UPLOADS.TXT
drwxrwxr-x 2 root wheel 512 Oct 5 1998 archive-info
lrwxr-xr-x 1 root wheel 21 Nov 22 1998 catalog.txt ->
pub/cdrom/catalog.txt
lrwxr-xr-x 1 root wheel 26 Nov 22 1998 config.txt ->
archive-info/wcarchive.txt
drwxr-xr-x 2 root wheel 512 May 2 1999 etc
drwxrwxr-x 2 root wheel 2048 Jun 12 20:53 pub
----------------------------------------------------------------------------
----
How do you read these Unix style directory listings?
The first byte of the first column tells you what type of file it is:
d : directory
- : file
l : a link to another file or directory
Following that are 9 letters indicating the permissions. The first three
are permissions for "the owner", the second three for "the group" and the
last three for "the world".
The access permissions are r=read, w=write, and x=execute. A dash ("-")
means the permission is not granted.
Read permission -- allows you to look at the file. In the case of a
directory, it let's you list the directory's contents.
Write permission -- allows you to modify (or delete) the file. In the case
of a directory, you must have write permission in order to create, move, or
delete files in that directory.
Execute permission -- allows you to execute the file by typing it's name.
With directories, execute permission allows you to "cd" into them.
The following combinations are possible: (Binary) (Octal)
"---" (no permissions) 000 0
"--x" (execute) 001 1
"-w-" (write-only, very rare) 010 2
"-wx" (write and execute, very rare) 011 3
"r--" (read-only) 100 4
"r-x" (read and execute) 101 5
"rw-" (read and write) 110 6
"rwx" (read, write and execute) 111 7
The second column is the number of links to the file.
The next 2 columns are the owner and user group to which the file belongs
(these can be numeric).
The next 2 columns are the file size and last modification date and
optional time.
The last column is the name of the file or directory or a link. The "->"
characters indicate a link. (This is like an alias, and is often used to
provide a shortcut to a file buried several subdirectories deep - it saves
keying). The links also are identified in byte 1 of the first column -
(l=link). A link can refer to either a directory or a file.
NOTE: some ftp servers may truncate the linked-to file name.
So, looking at a line like this:
-rw-r--r-- 1 ftpuser ftpusers 1498680 Jun 2 03:19 Index-byname
This is a file, ("-") in first byte of column 1
The owner has read and write permission (rw- , he'd better!) (octal 6)
The group has read permission only (r--) (octal 4)
The world has read permission only (r--) (octal 4)
There is 1 link to the file
The owner is ftpuser
The user group is ftpusers
The file size is 1498680 bytes
The date of last modification is Jun 02, 1999 at 03:19 local time
If there is no year shown, then it's the current year -- usually
The file name is Index-byname (which implies a text file and typically
is a complete listing of all files in all directories). The most
common of these names is 00index.txt
So the file permissions for this file would have an Octal value of 644.
--
Gerry Boyd
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