Linux commands: The difference between chmod, CHGRP, Chown

Chmod is the right to change the file;

CHGRP only changes the group of files;

Chown is the owner and genus of the changed file.

1.chmod: Change permissions for a file

There are two ways to set file permissions, namely numbers and tags .

Mode: Permission to set the string, the pattern is as follows: [Ugoa ...] [[+-=][RWXX] ...] [,...], where u implies that the owner of the file, G implies that the owner of the file belongs to the Group (group), and O implies that the other person, a implies that all three are.

+ hint add permission,-hint to dismiss permission, = imply only set permission.

R implies readable, W implies writable, X implies can be implemented, x implies only if the file is a subdirectory, presumably the file has been set to be implemented.

-S: The file in which the Master or group ID of the process is placed as the file owner.

C: If the file's permissions have been changed, it will show its movement

-F: Do not display error messages if the file permissions cannot be changed

-V: Specific information on performance of permission changes

-r: All the files under the present catalog are subject to different permission changes (that is, one by one, in a recursive way).

--HELP: Performance Help statement

--version: Performance version

Example: Set the file file1.txt to be read by all people:

chmod ugo+r File1.txt

Set the file file1.txt to be read by all people:

chmod a+r File1.txt

The file file1.txt and File2.txt are set to the owner of the file, and the person to whom it belongs can be written to, but not to the others:

chmod ug+w,o-w file1.txt File2.txt

Set the ex1.py to be available only to the owner of the file:

chmod u+x ex1.py

Set all files and subdirectories under the present catalog to be readable by anyone:

Chmod-r A+r *

When another user implements Oracle's Sqlplus this French, his identity is temporarily spawned by this French Oracle

chmod u+s Sqlplus

In addition, chmod can also use numbers to imply permissions such as chmod 777 file

The syntax is: chmod ABC file

Each of these a,b,c is a number, and the table represents the permissions of the user, Group, and other.

R=4,w=2,x=1

To rwx the attribute then 4+2+1=7;

To rw-the attribute then 4+2=6;

To r-x the property, 4+1=5.

Example:

chmod a=rwx file and chmod 777 file results are not different;

chmod ug=rwx,o=x file and chmod 771 file results are not different;

Using chmod 4755 filename allows the program to have root privileges.

I generally give the newly uploaded file chmod 755 file.

2.CHGRP: Change the group of files or directories

command format:　 chgrp The user group file name. If the entire directory is changed, the plus-r parameter is used for recursion.

#chgrp-R Guest/var/tmp/xx.txt

　　#chgrp-R root/home/xx/yy/a.txt

3.chown: Change the owner and genus of a file

　Command format:

　　A:chown-r-H User name file/Catalog

The-r option means that the same operation is done for files in all subdirectories, and the-h option means that the target file that the link points to is not affected when the owner of the symbolic link file is changed.

Note: Once ownership of a file is given to another user, it is no longer possible to reclaim its ownership and ultimately only to the system administrator.

B:chown User name: User group: File/Catalog

If the entire contents are changed, the plus-r parameter is used for recursion. Cases:

#chown Guest:guest A.txt

#chown Tomcat.root A.class

#chown-R Guest/home/berry (change all files under the Berry file to the guest group)

Linux commands: The difference between chmod, CHGRP, Chown