Special permissions on files and directories in linux are : SetUID, SetGID and Sticky bit.
With the help of “chmod” command we can implement the special permissions on file and directories.
SUID / Set User ID : A program is executed with the file owner's permissions (rather than with the permissions of the user who executes it).
SGID / Set Group ID : Files created in the directory inherit its GID, i.e When a directory is shared between the users , and sgid is implemented on that shared directory , when these users creates directory, then the created directory has the same gid or group owner of its parent directory.
Sticky Bit : It is used mainly used on folders in order to avoid deletion of a folder and its content by other user though he/she is having write permissions. If Sticky bit is enabled on a folder, the folder is deleted by only owner of the folder and super user(root). This is a security measure to suppress deletion of critical folders where it is having full permissions by others.
With the help of “chmod” command we can implement the special permissions on file and directories.
SUID / Set User ID : A program is executed with the file owner's permissions (rather than with the permissions of the user who executes it).
SGID / Set Group ID : Files created in the directory inherit its GID, i.e When a directory is shared between the users , and sgid is implemented on that shared directory , when these users creates directory, then the created directory has the same gid or group owner of its parent directory.
Sticky Bit : It is used mainly used on folders in order to avoid deletion of a folder and its content by other user though he/she is having write permissions. If Sticky bit is enabled on a folder, the folder is deleted by only owner of the folder and super user(root). This is a security measure to suppress deletion of critical folders where it is having full permissions by others.