((i=i+1))---------why要写2层括号？看不懂。作者: waker 时间: 2008-05-04 15:07
就这么约定的作者: meyu 时间: 2008-05-04 17:40
(())是调用 let 命令,用于计算作者: sdu_lizhipeng 时间: 2008-05-04 20:49
就是用(())来计算的.至于为什么不用三个括号或者四个,这个要问问语言设计者当初是怎么想....作者: walkerxk 时间: 2008-05-05 09:14
bash是谁写的？
AUTHORS
Brian Fox, Free Software Foundation bfox@gnu.org
Chet Ramey, Case Western Reserve University chet@po.cwru.edu
去问问他们吧。
(list) list is executed in a subshell environment (see COMMAND EXECUTION ENVIRONMENT below). Vari‐
able assignments and builtin commands that affect the shell’s environment do not remain in
effect after the command completes. The return status is the exit status of list.
((expression))
The expression is evaluated according to the rules described below under ARITHMETIC EVALUA‐
TION. If the value of the expression is non-zero, the return status is 0; otherwise the
return status is 1. This is exactly equivalent to let "expression".
我想一个括号的用掉了，接下来应该是用两个括号的，而不是三个、四个。
