BASH:
V2 = 1.1.1
i = 2
EVAL V1 = / $ V $ {i}
ECHO $ V1;
V1 becomes the index of V2, the value of V1 is 1.1.1
Function variable is $ 1 $ 2 $ 3
The program variable is $ 1 $ 2 $ 3
Perl in:
$ V2 {b} = 1.1.1;
$ I = 2;
$ I = v. $ i;
$ P = /% $ I
Print $ P -> {b};
$ p becomes a Hash V2 pointer
Function variable is $ _ [0] $ _ [1] $ _ [2] $ _ [3]
The program variable is $ argv [0] $ argv [1] $ argv [2]; $ argv [0] is pointing to the first parameter, not the program name.
two:
Actual User ID: Using ID Commands
Effective User ID: 1: You can change into file owner ID, (chmod s)
2: You can convert from root to other users with setuid (uid).
The valid user ID actually determines the user's permissions,
