Linux Learning Path-management of permissions

Rights Management

File permissions:

There are three types of user access to files:

r,w, x read, write, execute

Directory permissions (here the X permission and file are a bit different to note):

r: you can use the LS command to list files or subdirectories in a directory; Note: If only R permissions do not have x permissions, the files and subdirectories in that directory cannot be listed

W: You can create or delete files in this directory;

x : You can use ' ls-l ' to list the detailed property information of directory files and subdirectories; You can use the CD command to switch the working directory to the specified directory; simply, without x permission, you can't get to this directory

The permissions for a file are defined primarily for three types of objects:

Ownuer:u, owner;

Group:g, The genus Group;

Other:o, Other;

Tips , just remember R =4 w=2 X=1 can be, 421, there are suid,sgid, Sticky bit, just also 4 2 1 This order, so very good memory, also need to note, when the file or directory does not have X permission when suid, SGID and Sticky Bit flags S and T will become uppercase S, T, equal to this permission does not work

Rights Management:

Rights Management: Chmod

Affiliation Management: Chown, Chgrp

file Matte code: Umask

Modify file permissions: chmod

chmod [OPTION] ... Mode[,mode] ... FILE ...

chmod [OPTION] ... Octal-mode FILE ...

chmod [OPTION] ...--reference=rfilefile.

where the meaning of Ugoa:

U:owner

G:group

O:other

A:all

There are two ways to modify permissions:

One: =mode such as =rx, =r, = (Nothing on the back is written on behalf of what permissions are not)

ug=rx,go=

Two: [+|-]mode for example U+r,

chmod +w file or dir name

chmod u+r file or dir name

-r:recursive Recursive

modified file owner: Chown

chown [OPTION] ... [OWNER] [: [GROUP]] FILE ...

Chown[option] ...--reference=rfile FILE ...

-r:recursive Recursive

Example: chown root:root filename

chown root filename If you enter only one property, the default is owner

chown:root filename a colon plus a property that represents a group of changes

modified file group: Chgrp

Example: chgrp groupname filename

umask : Mask code (for the initial file, directory permissions settings, in reverse form, file, directory maximum permissions minus umask is the right to get, root default umask is 0022, ordinary user is 0002)

directory equals: 777-umask

file equals: 666-umask

CentOS in the system, the file default is not execute permission, if a certain type of user's permission to reduce the result has EXECUTE permission, this time will automatically let its permission bit plus 1;

Umaskumask

Set: Valid only for the current shell process;

Linux Learning Path-management of permissions