The learning experience of Linux permissions----ll, chmod command detailed __linux

ll command

Execute ll command (same ls-l), you can list the detailed information of the file, as shown below

1th column: The first word (file type-normal file "D is a folder") 9-bit permission (RWX (current user) rwx (user group) rwx (other user), if you do not have this permission to use-instead)

2nd Column: (quantity)

3rd Column: File owner

4th Column: File-owned user group (root belongs to root group)

5th column: File size

chmod command

1, Detailed:

(corresponding user) U: The owner of the file G: Group user o: Other users A: all Users--------"u (user), G (group), O (Other), A (All)" corresponding English

(appropriate permissions) r: File Read permissions (read) number code is 4,w: File Write permission (wrote) Digital code 2,x: File Execution authority The digital code name is 1,-: does not have any authority, the numeral code number is 0

2, as shown above, the Data folder has permissions of Rwxr-xr-x (the Hadoop user has read-R, write-W, execute-x permission (RWX)--------The HADDOP group has read-R, execute-X permissions (r-x)------------- Other users have read-R, execute-X permissions (R-x)

Add permissions: chmod o+w data to other users to add data file Write permission "where the parameter o corresponding user (for example, to the group of users to add permissions here is g), parameter w corresponding permissions (such as to increase the Read permission here is the parameter is R)" ———— Note: The plus sign represents increased permissions

Delete permission: chmod o-w data to other users to delete the Write permission of the data file "where parameter o corresponds to the user (for example, to give group users the right to add permissions here is g), parameter w corresponding permissions (such as to increase the Read permission here is the parameter is R)" ———— Note:

Digital notation: chmod data to the data directory read-R, write-W, execute-x permission, the group user rights are all deleted, the other user's permissions are deleted. —————— Note: 7 for r+w+x (4+2+1), such as to the data directory Hadoop users read, write, execute permissions, group users read and write permissions, other users read the permissions, as long as the implementation of the command chmod 764 data is OK.