Sh脚本`$？`是什么？

Question

我想知道$?的功能？

例如，如果变量的值为VARIABLE=$?

如果当然是操作员，有办法知道这种操作员。

Answer 1

$#    Stores the number of command-line arguments that 
      were passed to the shell program.
$?    Stores the exit value of the last command that was 
      executed.
$0    Stores the first word of the entered command (the 
      name of the shell program).
$*    Stores all the arguments that were entered on the
      command line ($1 $2 ...).
"$@"  Stores all the arguments that were entered
      on the command line, individually quoted ("$1" "$2" ...).

Answer 2

$？给你最后一个返回代码