read permission but cant ls -l it.

UNIX for Advanced & Expert Users
1

ok what is the signifigance of the -l that wont let you list the contents of a directory you clearly have access to list files. what am i missing

[qgatu003]/tmp$ls -l hold
hold/file1: Permission denied
total 0

[qgatu003]/tmp$ls hold
file1

[qgatu003]/tmp$ls -l
dr-x---r--   2 root     other        179 Apr 23 09:18 hold

edit::

i want to say its because i can not read the inode information from the file. does the system need to pull you to the files current directory in order to gets its full list of required arguments?......

2

You don't have access to the directory unix to list file attributes.

chmod 505 unix
and then a normal user would be able to ls -l unix and see the file1 ( even if file1 has -r--------- with owner root)

3

yeah i know if i add o+x i can list it. but why do you need to be able to enter the directory in order to read its contents is what i am trying to get at.

mabey i am not seeing the big picture or something but if you have read permission on a directory you should be able to list the file in all forms. apparently you need to be able to enter the directory to beable to read its inode information .... which i dont understand as to why.

4

Instead of x meaning search, think of it as "use" a directory.

With r permission only, you can list the files in a directory but you can't open them or stat them. And you can't cd to the directory either. The directory is reduced to being just a list filenames. It has sorta lost the special status that directories have.

With x permission only, you can cd to a directory but you can't list the files. If you happen to know a filename, you can open (file permissions allowing) or stat that file.

By the way, stat'ing a file is required for ls -l. stat'ing a file is also how "ls" gets an inode number. So "ls -i" needs x permission as well.

I don't think it makes sense to give a user just r or x on a directory. With me, it's always both or none.

5

504 perms you can do everything except (useing the command ls):
-R
-l
-n
-o
-g
-t
-p
-F
-s

which is kinda why i brought it up.

i mean you obvestly i can get some info from the filesystem abou the file but I cant read the inode info.

i can accept you need r-x to list files and its attributes.
but its i want to understand why i have to accept it.

6

I assume that this a directory that you don't own so that you are relying the 4 of 504.

The reason is that the stat system call is not working. Remember that a directory is just a list of filenames and inode numbers. Until you stat the the file, there is no way to know its size, owner, group, etc.

Why do you have to accept it? I guess you don't. But besides accepting it, what other choices do you see? Switch to another OS? Rewrite the kernel? Lobby for a change? Personally, I'd just live with it...

7

well... i do own it cuz i am the admin but i was just doing an exersize and came across it.

well after reading the man page for stat it just planly layes it out. You need to be able to use/execute the directory in order for the stat function to work.

DESCRIPTION
     The stat()  function  obtains  information  about  the  file
     pointed  to  by  path. Read, write, or execute permission of
     the named file is not required, but all  directories  listed
     in the path name leading to the file must be searchable.

as far as accepting it. why accept anything because someone says so. shouldnt you always question something to find out how it works. ie: dont blindly accept