Permissions for files

R (Read, reading): For a file, have permission to read the contents of the file, and for the directory, have permission to browse the directory.

W (write, writes): For the file, has the new, modifies the file content the permission, for the directory, has the deletion, moves the file inside the directory the permission.

X (Execute, execute): For the file, it has permission to execute the file, and for the directory, the user has permission to enter the directory.

s or S (suid,set UID): Executable file with this permission, can be privileged, arbitrary access to the file owner can use all the system
Resources. Please note that files with SUID permissions are often used by hackers to suid with the root account owner,
Silently open the back door in the system for future access.

T or T (Sticky):/tmp and/VAR/TMP directory for all users to temporarily access files, that is, each user has full access to the directory,
To browse, delete, and move files.

R,w,x is the basic permission S, T is a special permission,

Permissions for files