chmod in UNIX

Commands for changing Premission in UNIX:

chmod octal file – change the permissions of file to octal, which can be found separately for user, group, and world by adding:

4 – read (r)
2 – write (w)
1 – execute (x)

chmod commands :

> chmod 400 test : Making read only file for user
> chmod 777 dir1/ : Change file permissions and give all permissions for all user+group_other(file/directory)
> chmod u+w test : Change permissions only for user, group or others
> chmod g+w dir1/ : Change permissions only for Directories
> chmod u-w test : To remove file permission using (symbolic mode) chmod command
> chmod 555 test :  To remove file permission using (octal mode) chmod command
> chmod u-rw test : To remove read and write access from file for user/group/others with symbolic(file/directory)
> chmod a-rw test : To remove read and write access from file for all with symbolic(file/directory)
> chmod a=X 8 : Setting execute permission only on directories without touching files(chmod a+X *)
> chmod –reference test perk : To copy permission from one file to another (source_file destination_file)
> chmod u+r,g+w,o+x test : Changing multiple permissions in a file/directory