permission

Ammad · 05-25-2005, 01:05 AM

root user created a new file in /home/neo/file1
and set the permissions

#chmod 644 /home/neo/file1

when user neo log in and open the file named file1, in vi editor a message at botom [Read only file].
so after that neo change the file and quit using

:wq!

and changes successfully updated , file1 owner is root, group is root, and neo is not member of root group.

why this can be in vi , not in pico .

thanks take care coz i care

itsjustme · 05-25-2005, 07:00 PM

Hmmm... that is weird.

Code:

root@bsubuntu:/home/bs # touch test.txt
root@bsubuntu:/home/bs # ls -l test.txt
-rw-r--r--  1 root root 0 2005-05-25 18:57 test.txt
root@bsubuntu:/home/bs #

bs@bsubuntu:~$ ls -l test.txt
-rw-r--r--  1 root root 0 2005-05-25 18:57 test.txt
bs@bsubuntu:~$

bs@bsubuntu:~$ vi test.txt     (said read only.  saved it with :wq! )
bs@bsubuntu:~$ ls -l test.txt
-rw-r--r--  1 bs bs 5 2005-05-25 18:58 test.txt
bs@bsubuntu:~$

A dangerous thing, eh?

Sorry, don't know about pico.

Uh, and why is this in the networking forum?

mjrich · 05-25-2005, 07:07 PM

Yes, it is a rather strange feature of Vim...

It can be switched off by setting the cpoption "W" flag (see http://www.vim.org/htmldoc/editing.html#write-quit), though why it's there in the first place beats me. Only the account owner of /home/foobar can take ownership of files in their own directories using wq!, thus considering that they can't give away ownership after taking it, I guess it's not as bad as it sounds...

Cheers,

mj

Ammad · 05-25-2005, 10:49 PM

thanks mjrich for sharing knowledge

mjrich · 05-26-2005, 12:12 AM

Incidentally:

Code:

root:/home/test# touch foobar.txt
root:/home/test# ls -lh
total 0
-rw-r--r--   1 root    root       0 2005-05-26 16:50 foobar.txt

root:/home/test# exit
exit

user@debian:~$ rm foobar.txt 
rm: remove write-protected regular empty file `foobar.txt'? y

user@debian:~$ ls -lh
total 0
user@debian:~$

Which isn't too different from being able to write to a read-only file. Of course, outside the user's home directory, a 'permission denied' error is returned.

Cheers,

mj

kees-jan · 05-26-2005, 02:18 AM

Hi,

When saving a file, an editor (vi or pico or whatever) can do two things:
1. Write new data to the old file. Causes "permission denied" in this case. Apparently pico does this.
2. Alternatively, rename the oldfile to backup (or remove it alltogether) and create an entirely new file containing the new content. In order to do this, you need write permission for the directory the file is in, not for the file itself. Apparently, this is vi behaviour.

Groetjes,

Kees-Jan