UNIX for Dummies Questions & Answers

Hi all,
I want to know differences between read,write & execute permissons given to directory.
Thanx in advance.

Read: owner/group/other may list the directory contents
Write: owner/group/other may create new entries
eXecute: owner/group/other may chdir into directory

HTH

Hi pludi,
thanks for ur reply.But i think it is necessary to have read permisson to directory before write it .i mean if u give write permisson to directory & not read permisson will it work?

Of course. Simplest way to explain would be something like a suggestion box. Say you have a directory 'suggestions', with permissions set to 0722 (drwx-w--w-). User can edit their own files in that directory, but can't list files other users might have created. Only the owner of that directory can do that.

Hey,

Take a look at the FAQ article: https://www.unix.com/tips-tutorials/1...rmissions.html

HTH

Thanx my doubt get cleared.one more question what is 0 at starting of 0722
or d in drwx_w__w_.

The first number in this group of 4 is for the special bits. '0' means nothing, '1' is the "sticky bit", '2' the "set group ID", and '4' the "set user ID" bit. '4' is probably the most used of those, as it changes execution of a program so that it doesn't run as the calling UID, but as the one of the file owner (same for the SGID bit, only with the group instead of the user). The passwd utility most often has this one set, as it requires root privileges to change the password file, but any user should be able to run it.

The effects of the "sticky bit" vary between platforms, and whether it's set on a file or directory. For files it originally was intended to tell the kernel "Keep this file in memory after it ended" so that subsequent calls wouldn't need to reread it from disk (not working in Linux). For directories it means "only the owner of this file may manipulate it", eg. on the /tmp dir, where every user may write, but others shouldn't be able to delete or modify a file there.

The first character in an ls -l output (in your example 'd') specifies the file type. '-' is a regular file, 'd' is a directory, 'c' is a character device, ....

HTH