Birmingham mumbai

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The third section of the preceding code output shows us that 
doctor
 is the user 
that owns the file. Therefore, referring back to the table, the second column of the 
permission string (
rw-
) applies specifically to the user 
doctor
. Moving on, the third 
column of permissions is also three characters; in this case, 
rw-
 again. This section of 
the permissions string refers to 
the group that owns the file. In this case, the group 
is also named 
doctor
, as you can see in column four of the preceding code output. 
Finally, the last section of the permission string, visualized in the table (
rw-
 yet again, 
in this case), refers to world, also known as other. This basically refers to anyone else 
other than the owning user and owning group. Therefore, literally everyone else gets 
at least 
rw-
 permissions on the object.
Individually, 
r
 stands for 
read
 and 
w
 stands for 
write
. Therefore, we can read the 
second column (
rw-
), indicating that the user (
doctor
) has access to read and write 
to this file. The third column (
rw-
 again) tells us the 
doctor
 group also has read and 
write access to this file. The fourth column of the permission string is the same, so 
anyone else would also have read and write permissions to the file as well.
The third permission string I gave as an example looks a bit different. Here it is 
again:
-rwxr-xr-x 1 dalek dalek      35125 Nov  7  2013 exterminate
Here, we see the 
x
 attribute set. The 
x
 attribute refers to the ability to execute the 
file as a script. So, with that in mind, we know that this file is likely a script and is 
executable by users, groups, and others. Given the filename of 
exterminate
, this is 
rather suspicious, and if it were a real file, we'd probably want to look into it.
If a permission is not set, it will simply be a single hyphen where there would 
normally be 
r
, 
w
, or 
x
. This is the same as indicating that a permission is disabled. 
Here are some examples:
• 
rwx
: Object has read, write, and execute permissions set for this field
• 
r-x
: Object has read enabled, write disabled, and execute enabled for this 
field
• 
r--
: Object has read enabled, write disabled, and execute disabled for this 
field
• 
---
: Object has no permissions enabled for this field
Bringing this discussion all the way home, here are a few more permission strings:
-rw-r--r-- 1   sue   accounting      35125  Nov  7  2013 budget.txt 
drwxr-x--- 1   bob   sales           35125  Nov  7  2013 annual_
projects 

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Managing Users and Permissions