Permissions On files and Directory Basic

Hello Friends I am Deepak saini And today i am discusing the permissions on files and directory and how we are edit or set or check current permissions :)
Lets Start

There are three type of permission on a file or directory 
1 Read 
2 Write
3 Execute

1 Read :- In this permission we are able to list the content  of the directory but can't open  and execute the files we are only able to list the content of a directory. And in the case of file we are able to read the text but not the help of editors.We are using the cat command in this case of permission.

2 Write :- In this permission we are able to create the sub directory or file in the directory and we are able to move copy and delete in the directory.And in the case of file we are able to modify,cut,copy and paste the content of file.

3 Execute :- In this case of permission we are able to open or change the directory.And in the case of fiel we are able to run as program a file but not as text file.

How mention permission in the Red hat linux or others
There are two methods
1 Alphabetical
2 Numerical

Alphabetical        Numerical
r                           4
w                          2
x                           1
rwx                     7

Here r for read only and x for execute and w for write in alphabet .

Permissions on Directory in Red Hat linux or other
0 - no permissions
1 - can change the dir but can't list or create
2 - can not list and execute but create sub dir
3 - can not list but change and create in it
4 - only can list the content
5 - read and execute but can't write anything
6 - read and write but can't write anything
7 - full permissions

Permissions on a file
0 - no permissions
1- can execute only
2- can be append only
3- can be append and execute
4 - read only
5 - file can be read and execute but not modify
6 - file is a txt file and modify
7 - full permission


How the Default permissions are set ?
on directory
Default permission = full permission - umask
                                 777 - 022
                               =755(rwxr-xr-x)

umask by default set 022

On file
 Default permission = full permission - umask
                                 666 - 022
                              644(rw-r--r--)
How to Set umask manually
 umask <value of umask>
 value of umask like this 022 o 111 like this
 
Thanks for reading and Sorry for my R.I.P english :P _/\_ Jai Hind 

Posted in: Red Hat