Page 41 - RHEL8 BOOK

Default Permissions
File Directory

Created by root rw_r_ _ r _ _ 644 rwxr_ x r _ x 755
Created by user rw_rw _ r _ _ 664 rwxrwx r _ x 775

When a file created with the help of cat, touch, vi will get the permissions as 644.

- rw- r-- r—
i.e.
- read-write for the owner.
- read-only for the owners group and
- read-only for the others

Actually in the basic UNIX system when a file is created it gets the permission as 666. But this lapses in
security, so whenever a file is created in UNIX System it masks some bits, with a mask value of 022.

After masking we get the default value of a file as
644. [666 - 022 = 644]

022 is as the UMASK value.lt File Permission

To view the Umask value
[root@comp1 ~]#umask

To view Umask value from file
[root@comp1 ~]#vi /etc/bashrc

When a directory is created with the help of mkdir will get the permissions as 755.
d rwx r-x r-xfault Directory Permission
Actually in the basic UNIX system when a directory is created it gets the permission as 777. But this
lapses in security, so when ever a directory is created in UNIX system it masks some bits, with a mask
value of 022.
After masking we get the default value of a file as 777. [777 - 022 = 755]
022 is as the UMASK value.

fault Directry Permission
Chmod: - command is used to change the permissions of a file/directory.
chmod can be used by the owner of the file or by root. With chmod command we can assign permissions
or remove permissions as required.

S. Pradhan
(MCA, MBA-IT, BCA, CCNA, MCSA 2012, RHCE, ETHICAL HACKING)
Email Id:-spradhan.iiht@gmail.com
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