Logical Operators::
&&: means to execute command a first, and then execute command b if it is successful, which is also called a short-circuit operator.
&: means to execute command a first and then execute command b, regardless of whether a is successful or not, command b will be executed. In terms of execution efficiency, "&&" is more efficient.
||: means to execute command a first and then command b. Only when command a fails to execute, command b will be executed.
|: It means to execute the command a first, and then execute the command b, no matter whether the command a is successful or not, the command b will be executed.
(When the first command fails, it still executes the second command, representing the output of the A command statement, executed as the input of the B command statement.)
exec “ping”
127.0.0.1 & ipconfig
exec “eval”
Rookie tutorial eval() function
evalFunction to execute a string as PHP code
phpinfo();
